Imaging device, method of operating the imaging device, and operating program of the imaging device

Abstract

The present invention provides an imaging device, an operating method for the imaging device, and an operating program for the imaging device that can improve the reliability of the focus position of the focus lens determined during continuous shooting. [Solution] The imaging device includes a determination unit. In continuous shooting, the determination unit uses the first focus position of the focus lens at the first time point to determine the second focus position of the focus lens at the second time point, which is after the first time point. The determination unit receives a shooting preparation instruction, and if the set conditions are met, it uses the first focus position acquired after the shooting preparation instruction to determine the second focus position.

Description

Technical Field

[0001] The technology of the present disclosure relates to an imaging device, a method for operating the imaging device, and an operation program for the imaging device.

[0002] Patent Document 1 describes an imaging device including a processor and an image sensor on which light is imaged by an imaging lens including a focus lens. The focus lens moves while avoiding the period of main exposure by the image sensor according to an instruction from the processor, and continuous shooting is performed by continuously performing main exposure by the image sensor at a predetermined time interval. During the continuous shooting period, the processor calculates a first focusing position of the focus lens with respect to a specific subject based on image data obtained by imaging the specific subject with main exposure by the image sensor in a specific frame where main exposure is performed, and refers to the first focusing positions for a plurality of frames during the continuous shooting period to predict a second focusing position of the focus lens with respect to the specific subject a plurality of frames after the specific frame.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] One embodiment of the technology according to the present disclosure provides an imaging device, a method for operating the imaging device, and an operation program for the imaging device that can enhance the reliability of the focusing position of a focus lens determined in continuous shooting.

Means for Solving the Problems

[0005] The imaging device of this disclosure is an imaging device that, in continuous shooting, determines the second focus position of the focus lens at a second time point after the first time point using information regarding the first focus position of the focus lens at a first time point, and comprises a processor, which receives a first imaging instruction and, if a preset condition is met, determines the second focus position using information regarding the first focus position acquired after the first imaging instruction.

[0006] It is preferable that the first and second time points, when the first imaging instruction is received and the conditions are met, are after the first imaging instruction.

[0007] Preferably, when the processor receives a first imaging instruction and the conditions are met, it determines the second focus position without using information about the first focus position acquired before the first imaging instruction.

[0008] Preferably, the interval between the first imaging instruction and the second imaging instruction, which occurs after the first imaging instruction, is less than a preset threshold interval.

[0009] Preferably, the difference between the position of the focus lens before the first imaging instruction and the first focus position is greater than or equal to a preset threshold difference.

[0010] The processor performs a through-image output process that outputs a through-image of the subject, and preferably, it derives information regarding at least the first focus position but does not move the focus lens to the second focus position, and the difference is the difference between the position of the focus lens in the through-image output process immediately before the first imaging instruction is given and the first focus position.

[0011] If the interval between the first imaging instruction and the second imaging instruction, which occurs after the first imaging instruction, is greater than or equal to a preset threshold interval, the processor preferably determines the second focus position using information about the first focus position acquired before the first imaging instruction.

[0012] If the difference between the position of the focus lens before the first imaging instruction and the first focus position is less than a preset threshold difference, the processor preferably determines the second focus position using the information about the first focus position acquired before the first imaging instruction.

[0013] The processor preferably determines the second focus position using information about the first focus position acquired before the first imaging instruction if the interval between the first imaging instruction and the second imaging instruction, which occurs after the first imaging instruction, is greater than or equal to a preset threshold interval, and if the difference between the position of the focus lens before the first imaging instruction and the first focus position is less than a preset threshold difference.

[0014] For continuous shooting, there are two modes: continuous mode, which continuously moves the focus lens to the second focus position output in a time series, and single mode, which keeps the focus lens fixed at a single second focus position. Preferably, when the conditions are met in continuous mode, the processor determines the second focus position using information about the first focus position acquired after the second imaging instruction (after the first imaging instruction), without using information about the first focus position acquired before the first imaging instruction. If it is in single mode, it is preferable to determine the second focus position using information about the first focus position acquired before the first imaging instruction.

[0015] For continuous shooting, there are two modes: a release-priority mode that prioritizes the operation of the release button over the focus state of the focus lens, and a focus-priority mode that prioritizes the focus state of the focus lens over the operation of the release button. Preferably, when the conditions are met in release-priority mode, the processor determines the second focus position using information about the first focus position acquired after the second imaging instruction (after the first imaging instruction), without using information about the first focus position acquired before the first imaging instruction. If it is in focus-priority mode, it is preferable to determine the second focus position using information about the first focus position acquired before the first imaging instruction.

[0016] Preferably, the first imaging instruction corresponds to a half-press operation of the shutter release button, and the second imaging instruction, which follows the first imaging instruction, corresponds to a full-press operation of the shutter release button.

[0017] The method for operating an imaging device according to this disclosure is a method for operating an imaging device that, in continuous shooting, determines the second focus position of the focus lens at a second time point after the first time point using information regarding the first focus position of the focus lens at a first time point, and includes receiving a first imaging instruction and, if a preset condition is met, determining the second focus position using information regarding the first focus position acquired after the first imaging instruction.

[0018] The operating program for the imaging device of this disclosure is an operating program for an imaging device that, in continuous shooting, determines the second focus position of the focus lens at a second time point after the first time point using information regarding the first focus position of the focus lens at a first time point, and causes a computer to execute a process that includes receiving a first imaging instruction and, if a preset condition is met, determining the second focus position using information regarding the first focus position acquired after the first imaging instruction. [Brief explanation of the drawing]

[0019] [Figure 1] This is a front view of the imaging device. [Figure 2] This is a rear view of the imaging device. [Figure 3] This is a block diagram showing the electrical configuration of the imaging device. [Figure 4] This diagram shows the arrangement of pixels in an image sensor. [Figure 5] This figure shows the typical pixel configuration. [Figure 6] This figure shows the configuration of the first phase difference detection pixel. [Figure 7] This figure shows the configuration of the second phase difference detection pixel. [Figure 8] This graph shows the phase difference between the first and second calculation signals. [Figure 9] This is a diagram showing the focus adjustment area. [Figure 10] It is a diagram showing calculation data, where (A) shows the first calculation data and (B) shows the second calculation data. [Figure 11] It is a diagram showing two modes of the continuous shooting mode, where (A) shows the continuous mode and (B) shows the single mode. [Figure 12] It is a diagram showing two modes of the continuous shooting mode, where (A) shows the release priority mode and (B) shows the focus priority mode. [Figure 13] It is a diagram showing the through-image output process. [Figure 14] It is a block diagram showing the detailed configuration of the control unit. [Figure 15] It is a block diagram showing the processing unit of the CPU. [Figure 16] It is a diagram showing the processing of the determination unit. [Figure 17] It is a diagram showing the processing of the derivation unit. [Figure 18] It is a diagram showing the setting conditions. [Figure 19] It is a timing chart showing the through-image output process, the shooting preparation process, and the derivation of the first focus position, the determination of the second focus position, the movement of the focus lens, and the transition of image output or image recording in continuous shooting. (A) shows the case where the interval between the half-press operation and the full-press operation of the release button is greater than or equal to the threshold interval, and (B) shows the case where the interval between the half-press operation and the full-press operation of the release button is less than the threshold interval. [Figure 20] It is a diagram showing a scene where the distance between the imaging device and the subject varies greatly. (A) shows the case where a distant mountain is the subject, and (B) shows the case where the subject is switched from a distant mountain to a close-up person. [Figure 21] It is a flowchart showing the processing procedure when the second focus position is determined in the determination unit. [Figure 22] It is a diagram showing the transition of the first focus position, the second focus position, and the current position of the focus lens in the conventional example. [Figure 23]This figure shows the progression of the first focus position, the second focus position, and the current position of the focus lens in this example. [Figure 24] This diagram shows the processing procedure of the focusing control unit. [Figure 25] This graph shows the progression of the first focus position, the second focus position, and the current position of the focus lens when the hold function is enabled. [Modes for carrying out the invention]

[0020] As an example, as shown in Figures 1 and 2, the imaging device 10 is, for example, a digital camera and comprises a device body 11. An imaging lens 13 and the like are arranged on the front 12 of the device body 11. A liquid crystal monitor 15 and the like are arranged on the rear 14 of the device body 11, which faces the front 12. Furthermore, various operating members such as a power switch integrated release button (hereinafter simply referred to as the release button) 17 are arranged on the top surface 16 of the device body 11, which connects the front 12 and the rear 14. A tripod screw hole (not shown) and the like are arranged on the bottom surface 18 of the device body 11, which is the other surface connecting the front 12 and the rear 14. The imaging device 10 may also be an interchangeable-lens camera in which the imaging lens 13 can be replaced.

[0021] An image sensor 19 is positioned behind the imaging lens 13. The image sensor 19 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor. The image sensor 19 has an imaging surface 20 that captures subject light. The image sensor 19 is positioned so that the center of the imaging surface 20 coincides with the optical axis OA of the imaging lens 13, and the imaging surface 20 is perpendicular to the optical axis OA. Here, "coincidence" and "perpendicularity" refer not only to perfect coincidence and orthogonality, but also to coincidence and orthogonality that include errors generally accepted in the art to which the technology of this disclosure belongs.

[0022] As an example, as shown in Figure 3, the imaging lens 13 has multiple types of lenses for forming an image of the subject on the image sensor 19. Specifically, the imaging lens 13 has an objective lens 25, a focusing lens 26, and a zoom lens 27. These lenses 25 to 27 are arranged in this order from the object side (subject side) to the image-forming side (image sensor 19 side). Although simplified in Figure 3, each lens 25 to 27 is actually a lens group made up of multiple lenses combined together.

[0023] A focus lens drive mechanism 28 is connected to the focus lens 26, and a zoom lens drive mechanism 29 is connected to the zoom lens 27. The focus lens drive mechanism 28 includes a focus cam ring that holds the focus lens 26 and has a cam groove formed on its outer circumference, a focus motor that rotates the focus cam ring around the optical axis OA to move the focus cam ring along the optical axis OA, and a driver for the focus motor. Similarly, the zoom lens drive mechanism 29 includes a zoom cam ring that holds the zoom lens 27 and has a cam groove formed on its outer circumference, a zoom motor that rotates the zoom cam ring around the optical axis OA to move the zoom cam ring along the optical axis OA, and a driver for the zoom motor.

[0024] An aperture 30 is positioned on the imaging side of the imaging lens 13. The aperture 30 is, for example, an iris diaphragm, and is composed of a combination of multiple aperture blades. The aperture 30 adjusts the amount of light passing through by simultaneously moving the aperture blades with a cam mechanism to open and close the central opening formed by the inner edges of the aperture blades, that is, by changing the opening degree of the opening. An aperture opening adjustment mechanism 31 is connected to the aperture 30. The aperture opening adjustment mechanism 31 includes an aperture motor for opening and closing the aperture blades, and a driver for the aperture motor, etc.

[0025] Various motors, such as the focus motor, zoom motor, and aperture motor, are, for example, stepping motors. In this case, the position of the focus lens 26 and the zoom lens 27 on the optical axis OA, as well as the opening degree of the aperture 30, can be derived from the drive amounts of the focus motor, zoom motor, and aperture motor. Alternatively, instead of using the drive amounts of the focus motor and zoom motor, position sensors may be provided to detect the positions of the focus lens 26 and the zoom lens 27.

[0026] The motors (focus motor, zoom motor, and aperture motor) or electrical components such as drivers of each drive mechanism 28, 29, and 31 are connected to the control unit 32. The electrical components of each drive mechanism 28, 29, and 31 are driven under the control of the control unit 32. More specifically, the control unit 32 drives the electrical components of each drive mechanism 28, 29, and 31 by issuing drive signals in response to user instructions input via the operation unit 33. For example, if an instruction to change the angle of view to the telephoto side is input via the angle of view change switch included in the operation unit 33, the control unit 32 issues a drive signal to the driver of the zoom motor of the zoom lens drive mechanism 29, causing the zoom lens 27 to move to the telephoto side.

[0027] The operation unit 33 is a general term for user-operated components such as the menu button and directional keys, in addition to the aforementioned release button 17. Here, the release button 17 is a two-stage push button that can be half-pressed and fully pressed. Half-pressing the release button 17 issues a command to prepare for still image or video shooting, and fully pressing it issues a command to start still image or video shooting. The shooting preparation command is an example of a "first imaging command" related to the technology of this disclosure. The shooting start command is an example of a "second imaging command" related to the technology of this disclosure.

[0028] The control unit 33 also includes a mode switch for switching the operating mode of the imaging device 10. The operating modes include still image shooting mode, video shooting mode, image playback mode, and setting mode. The still image shooting mode includes not only the normal shooting mode for taking a single still image, but also a continuous shooting mode for continuously taking still images at a predetermined shooting interval, for example, a frame rate of 5fps (frames per second) to 10fps. The continuous shooting mode is activated, for example, when the release button 17 is held fully pressed for a predetermined period of time or longer. The continuous shooting mode ends when the fully pressed state of the release button 17 is released.

[0029] The focus motor, zoom motor, and aperture motor output drive amounts to the control unit 32. The control unit 32 derives the position of the focus lens 26, the position of the zoom lens 27, and the opening degree of the aperture 30 on the optical axis OA from the drive amounts.

[0030] An image sensor driver 34 is connected to the image sensor 19. The image sensor driver 34 is connected to the control unit 32. Under the control of the control unit 32, the image sensor driver 34 controls the timing of image acquisition by the image sensor 19 by supplying vertical scanning signals and horizontal scanning signals to the image sensor 19.

[0031] A shutter 35 is positioned between the imaging lens 13 and the image sensor 19. The shutter 35 is, for example, a focal-plane shutter having a front curtain and a rear curtain. A shutter drive mechanism 36 is connected to the shutter 35. The shutter drive mechanism 36 includes an electromagnet, motor, charge lever, and driver, etc., for holding the front curtain and the rear curtain and releasing the holding to move the front curtain and the rear curtain. The shutter drive mechanism 36 is driven under the control of the control unit 32 to open and close the shutter 35.

[0032] The control unit 32 is connected to various components such as the image input controller 40, image memory 41, and image processing unit 42 via a bus line 43. Other components connected to the bus line 43 include VRAM (Video Random Access Memory) 44, display control unit 45, media controller 46, and instruction receiving unit 47. Although not shown in the diagram, the bus line 43 is also connected to a strobe drive control unit that controls the operation of the strobe device, an external communication interface (I / F) that communicates with external devices via connection terminals such as a USB (Universal Serial Bus) terminal, and a wireless communication interface (I / F) that communicates with external devices via a wireless antenna.

[0033] The image input controller 40 receives image data obtained by capturing the subject light from the image sensor 19. The image input controller 40 outputs the image data to the image memory 41. The image memory 41 is, for example, SDRAM (Synchronous Dynamic Random Access Memory) and temporarily stores the image data.

[0034] The image processing unit 42 reads unprocessed image data from the image memory 41. The image processing unit 42 performs various image processing operations on the image data. These operations include, for example, offset correction, sensitivity correction, pixel interpolation, white balance correction, gamma correction, demosaicing, luminance signal and chrominance signal generation, edge enhancement, and color correction. The image processing unit 42 then writes the processed image data back to the image memory 41.

[0035] Image data that has undergone various image processing and is intended to be displayed as a through image is input to VRAM44 from image memory41. VRAM44 has an area for storing image data for two consecutive frames. The image data stored in VRAM44 is sequentially overwritten with new image data. VRAM44 sequentially outputs the newer image data from the two consecutive frames of image data to display control unit45.

[0036] The display control unit 45 performs the function of a so-called video encoder, converting image data from the VRAM 44 into video data and outputting it to the liquid crystal monitor 15. This allows the user to view the through-image through the liquid crystal monitor 15. The display frame rate of the through-image is, for example, 60fps.

[0037] When the shutter release button 17 is fully pressed to initiate still image or video recording, the image processing unit 42 compresses the image data in the image memory 41. For still images, the image processing unit 42 compresses the image data using, for example, the JPEG (Joint Photographic Experts Group) format. For videos, the image processing unit 42 compresses the image data using, for example, the MPEG (Moving Picture Experts Group) format. The image processing unit 42 then outputs the compressed image data to the media controller 46.

[0038] The media controller 46 records the compressed image data from the image processing unit 42 onto the memory card 48. The memory card 48 is detachably mounted in a memory card slot (not shown).

[0039] When the image playback mode is selected via the mode switch on the operation unit 33, the media controller 46 reads image data from the memory card 48 and outputs it to the image processing unit 42. The image processing unit 42 performs a decompression process on the image data from the memory card 48. The decompressed image data is output to the display control unit 45. The display control unit 45 converts the image data into video data and outputs it to the liquid crystal monitor 15. As a result, the user can view the playback image through the liquid crystal monitor 15.

[0040] The instruction receiving unit 47 receives various operation instructions from the user via the operation unit 33 and the touch panel 49, which is integrated with the liquid crystal monitor 15. The instruction receiving unit 47 outputs the received operation instructions to the control unit 32 via the bus line 43. The touch panel 49 is superimposed on the display surface of the liquid crystal monitor 15. The touch panel 49 recognizes various operation instructions from the user by detecting contact with the user's finger or a dedicated indicator such as a stylus pen.

[0041] As an example, as shown in Figure 4, the image sensor 19 is provided with a photoelectric conversion unit 55. The photoelectric conversion unit 55 is composed of a plurality of pixels 56 arranged two-dimensionally along the X and Y directions. The plurality of pixels 56 form an imaging surface 20. As is well known, the pixels 56 are composed of photoelectric conversion elements 62 such as microlenses 60, color filters 61, and photodiodes (see Figures 5 to 7). The X and Y directions are the horizontal and vertical directions when the bottom surface 18 of the imaging device 10 is placed on a horizontal surface.

[0042] Scan lines parallel to the X direction are wired between the rows of pixels 56. Signal lines parallel to the Y direction are wired between the columns of pixels 56. Each pixel 56 (photoelectric conversion element 62) is connected to the signal lines via an amplifier and a switch. The scan lines are also connected to the switch. In the case of storage operation, where a signal charge corresponding to the subject light is stored in the pixel 56 (photoelectric conversion element 62), an off signal is supplied as a vertical scan signal through the scan line, turning the switch off. In the case of readout operation, where an image signal (voltage signal) 57 corresponding to the signal charge is read from the pixel 56 (photoelectric conversion element 62), an on signal is supplied as a vertical scan signal through the scan line, turning the switch on. The ends of the signal lines are connected to a CDS (Correlated Double Sampling) circuit and an ADC (Analog to Digital Converter) circuit. The CDS circuit performs correlated double sampling on the image signal 57 input through the signal lines. The ADC circuit converts the image signal 57 after correlated double sampling into a digital image signal 57.

[0043] Pixels 56 are divided into three types depending on the type of color filter 61: green pixels (labeled "G" in Figure 4) that are sensitive to light in the green wavelength band, red pixels (labeled "R" in Figure 4) that are sensitive to light in the red wavelength band, and blue pixels (labeled "B" in Figure 4) that are sensitive to light in the blue wavelength band. The three types of pixels 56 are arranged regularly in a predetermined array. As a predetermined array, the so-called Bayer array is shown as an example, in which two green pixels, one blue pixel, and one red pixel are placed in a 2x2 pixel grid.

[0044] Pixel 56 consists of normal pixels 56N and phase-difference detection pixels 56P. Phase-difference detection pixels 56P are further divided into first phase-difference detection pixels 561P and second phase-difference detection pixels 562P. Normal pixels 56N come in three types: green, blue, and red, but phase-difference detection pixels 56P consist only of green pixels.

[0045] The phase difference detection pixels 56P are arranged at predetermined intervals in the X and Y directions. In Figure 4, the phase difference detection pixels 56P are arranged at intervals of 5 pixels in the X direction and 2 pixels in the Y direction. Furthermore, the phase difference detection pixels 56P are arranged such that the first phase difference detection pixels 561P and the second phase difference detection pixels 562P appear alternately in the X and Y directions. For example, looking at the 4th row, the phase difference detection pixels 56P are arranged from left to right in the order of second phase difference detection pixel 562P, first phase difference detection pixel 561P, ... Also, for example, looking at the 10th column, the phase difference detection pixels 56P are arranged from top to bottom in the order of second phase difference detection pixel 562P, first phase difference detection pixel 561P, second phase difference detection pixel 562P, first phase difference detection pixel 561P, ... The first phase difference detection pixel 561P and the second phase difference detection pixel 562P, which are adjacent in the X and Y directions, constitute a set for detecting the phase difference α (see Figure 8).

[0046] As an example, as shown in Figures 5 to 7, the normal pixel 56N, the first phase difference detection pixel 561P, and the second phase difference detection pixel 562P have the same basic configuration. That is, the normal pixel 56N, the first phase difference detection pixel 561P, and the second phase difference detection pixel 562P are composed of a microlens 60, a color filter 61, and a photoelectric conversion element 62 arranged in order from the object side.

[0047] As shown in Figure 5, the photoelectric conversion element 62 of the normal pixel 56N outputs an image generation signal 57N as an image signal 57, corresponding to the subject light that has been focused by the microlens 60 and passed through the color filter 61. The image generation signal 57N is stored in the image memory 41 as part of the image data.

[0048] As shown in Figures 6 and 7, a light-shielding member 63 is placed between the color filter 61 and the photoelectric conversion element 62 of the first phase difference detection pixel 561P and the second phase difference detection pixel 562P. This light-shielding member 63 is not normally placed in the pixel 56N. The light-shielding member 63 of the first phase difference detection pixel 561P shields the right half of the photoelectric conversion element 62 when viewed from the object side. In contrast, the light-shielding member 63 of the second phase difference detection pixel 562P shields the left half of the photoelectric conversion element 62 when viewed from the object side.

[0049] The photoelectric conversion element 62 of the first phase difference detection pixel 561P outputs a first calculation signal 571P as an image signal 57, corresponding to the subject light that is focused by the microlens 60, passes through the color filter 61, and whose right half is blocked by the light-shielding member 63. In contrast, the photoelectric conversion element 62 of the second phase difference detection pixel 562P outputs a second calculation signal 572P as an image signal 57, corresponding to the subject light that is focused by the microlens 60, passes through the color filter 61, and whose left half is blocked by the light-shielding member 63. The first calculation signal 571P and the second calculation signal 572P are stored in the image memory 41 as part of the image data, just like the image generation signal 57N. In the following, unless there is a particular need to distinguish between them, the first calculation signal 571P and the second calculation signal 572P will be collectively referred to as calculation signal 57P.

[0050] As an example, as shown in Figure 8, a phase difference α appears between the first calculation signal 571P and the second calculation signal 572P output from the first phase difference detection pixel 561P and the second phase difference detection pixel 562P, which are adjacent in the X and Y directions. The phase difference α is also called parallax. This phase difference α indicates which direction and by how much the focus lens 26 needs to be moved to achieve the in-focus position. The control unit 32 derives the in-focus position of the focus lens 26 based on the phase difference α and performs automatic focusing control to automatically move the focus lens 26 to the in-focus position. The first in-focus position FP1 is an example of "information relating to the first in-focus position" related to the technology of this disclosure.

[0051] As an example, as shown in Figure 9, the area 65 for deriving the first focus position FP1 (hereinafter referred to as the focus adjustment area) is pre-set in the center of the imaging plane 20. The focus adjustment area 65 is a rectangular area that is long in the X direction. Multiple focus adjustment areas 65 are set; in this case, eight are set.

[0052] The focus adjustment area 65 may be an area specified by the user, or an area surrounding a specific subject recognized by a well-known subject recognition technology. A specific subject may be the pupil, face, or torso of a person, the pupil, face, or torso of an animal, or the front or torso of a vehicle such as an automobile, railway car, or airplane. Here, the pupil of a person or animal refers to the pupil, or the black part of the eye. The face of a person or animal refers to the part that has the forehead, cheeks, chin, eyes, nose, mouth, ears, etc. The torso of a person or animal refers to the part excluding the head, neck, limbs, and tail. The front of a vehicle refers to the front body of an automobile, the part of a railway car that has the destination indicator, front windshield, headlights, etc. of the leading car, or the nose section of an airplane that has the radome, front windshield, etc. The torso of a vehicle refers to the entire body excluding the wheels of an automobile, the entire body excluding the wheels of a railway car, regardless of whether it is the leading car, middle car, or last car, or the entire body excluding the nose, main wings, tail wings, etc. of an airplane. The focus adjustment area 65 may be the entire imaging surface 20.

[0053] The image generation signal 57N, as its name suggests, is used to generate captured images such as through images. In contrast, the calculation signal 57P is used only to derive the phase difference α and, consequently, the first focus position FP1, and is not used to generate captured images. Therefore, in the pixel interpolation process, the image processing unit 42 interpolates the pixel value of the phase difference detection pixel 56P using the image generation signal 57N of the normal pixels 56N surrounding the phase difference detection pixel 56P.

[0054] Here, the calculation signal 57P is specifically divided into first calculation data DC1, shown in Figure 10(A) as an example, and second calculation data DC2, shown in (B). The first calculation data DC1 is data obtained by arranging multiple first calculation signals 571P output from the first phase difference detection pixel 561P in a two-dimensional manner in the X and Y directions, following the arrangement of the first phase difference detection pixel 561P. The second calculation data DC2 is data obtained by arranging multiple second calculation signals 572P output from the second phase difference detection pixel 562P in a two-dimensional manner in the X and Y directions, following the arrangement of the second phase difference detection pixel 562P. These first calculation data DC1 and second calculation data DC2 can be treated as two-dimensional image data. In the following, unless there is a particular need to distinguish between them, the first calculation data DC1 and the second calculation data DC2 will be collectively referred to as calculation data DC.

[0055] As an example, as shown in Figure 11, there are two continuous shooting modes: (A) continuous mode and (B) single mode. Continuous mode is a mode in which focus control is performed each time an image is recorded. Focus control includes deriving a first focus position FP1 (see Figure 15) using calculation data DC, determining a second focus position FP2 (see Figure 15) using the first focus position FP1, and moving the focus lens 26 to the second focus position FP2. Therefore, in continuous mode, the movement of the focus lens 26 to the second focus position FP2, which is determined in chronological order, is performed continuously. Continuous mode is suitable for continuous shooting of moving subjects such as a running person, a flying bird, or a moving train.

[0056] In contrast, the single mode is a mode in which the state is maintained when the difference between the current position of the focus lens 26 (hereinafter referred to as the current position) CP (see Figure 22) and the second focus position FP2 falls within an acceptable range. For this reason, in single mode, the focus lens 26 is fixed at one second focus position FP2. The current position CP is an example of the "focus lens position" related to the technology disclosed herein. Unlike the continuous mode, the single mode is suitable for continuous shooting of stationary subjects. The acceptable range is defined as the range in which the human eye can perceive the image as being in focus. The continuous mode and single mode are selected by the user, for example, in the settings mode.

[0057] Furthermore, as shown in Figure 12 as an example, the continuous shooting mode has two modes: (A) release priority mode and (B) focus priority mode. The release priority mode is a mode that prioritizes the operation of the release button 17 over the focus state of the focus lens 26. For this reason, in release priority mode, images are recorded even when the difference between the current position CP of the focus lens 26 and the second focus position FP2 is outside the acceptable range.

[0058] In contrast, the focus priority mode, unlike the release priority mode, prioritizes the focus state of the focus lens 26 over the operation of the release button 17. Therefore, in focus priority mode, images are not recorded when the difference between the current position CP and the second focus position FP2 of the focus lens 26 is outside the acceptable range. In focus priority mode, image recording begins only when the difference between the current position CP and the second focus position FP2 of the focus lens 26 is within the acceptable range. Both the release priority mode and the focus priority mode can be selected by the user, for example, in the settings mode.

[0059] As an example, as shown in Figure 13, when the release button 17 is not operated, the control unit 32 performs through-image output processing to output a through-image of the subject. Specifically, the through-image output processing involves acquiring image data from the image sensor 19, applying various image processing to the image data, and outputting the processed image data as a through-image to the VRAM 44 at intervals corresponding to the display frame rate. In the through-image output processing, the control unit 32 performs the derivation of the first focus position FP1 and the determination of the second focus position FP2 as part of the focus control, but does not move the focus lens 26 to the second focus position FP2. Therefore, a blurred through-image may be displayed on the liquid crystal monitor 15. Note that in the focus control of the through-image output processing, it is also acceptable to limit the process to only the derivation of the first focus position FP1.

[0060] As an example, as shown in Figure 14, the control unit 32 includes storage 70, a CPU (Central Processing Unit) 71, and memory 72. These storage 70, CPU 71, and memory 72 are interconnected via a bus line 73. The control unit 32 is an example of a "computer" according to the technology of this disclosure.

[0061] Storage 70 is a non-volatile storage device, such as EEPROM (Electrically Erasable Programmable Read-Only Memory). Storage 70 stores various programs and various data associated with those programs. Alternatively, FeRAM (Ferroelectric Random Access Memory) or MRAM (Magnetoresistive Random Access Memory) may be used as storage 70 instead of EEPROM.

[0062] Memory 72 is a work memory for the CPU 71 to execute processing. The CPU 71 loads the program stored in storage 70 into memory 72 and executes processing according to the program. In this way, the CPU 71 comprehensively controls each part of the imaging device 10. CPU 71 is an example of a "processor" related to the technology of this disclosure. Note that memory 72 may be built into the CPU 71.

[0063] As an example, as shown in Figure 15, the storage 70 stores an operation program 75. The operation program 75 is a program that causes the CPU 71 to perform automatic focusing control, etc. In other words, the operation program 75 is an example of an "operation program for an imaging device" related to the technology of this disclosure. The storage 70 also stores setting conditions 76. The setting conditions 76 are an example of "pre-set conditions" related to the technology of this disclosure.

[0064] When the operating program 75 is started, the CPU 71 works in cooperation with the memory 72 and other components to function as the focus control unit 78. The focus control unit 78 includes a derivation unit 80, a determination unit 81, and a focus lens drive control unit 82. In addition to the focus control unit 78, the CPU 71 also functions as various other processing units.

[0065] The focus control unit 78 receives the drive amount 85 of the focus motor from the focus lens drive mechanism 28. The focus control unit 78 derives the current position CP of the focus lens 26 from the drive amount 85.

[0066] The derivation unit 80 reads the calculation data DC from the image memory 41. The derivation unit 80 detects the phase difference α shown in Figure 8 from the calculation data DC of the focus adjustment region 65. The derivation unit 80 derives the first focus position FP1 from the phase difference α. The derivation unit 80 outputs the derived first focus position FP1 to the determination unit 81.

[0067] The determination unit 81 stores the first focus position FP1 previously derived by the derivation unit 80 for multiple consecutive frames. As an example, as shown in Figure 16, the determination unit 81 predicts the position of a subject that is thought to be present in the next frame, for example, based on the first focus position FP1 derived for, for example, two frames ago, one frame ago, and the current frame. Then, it determines a second focus position FP2 corresponding to the predicted position of the subject. The dashed line is a prediction curve corresponding to the first focus position FP1 derived for two frames ago, one frame ago, and the current frame. The first focus position FP1 derived for two frames ago, one frame ago, and the current frame is an example of "information relating to the first focus position of the focus lens at a first time point" according to the technology of this disclosure. The second focus position FP2 of the next frame after the current frame is an example of "the second focus position of the focus lens at a second time point after the first time point" according to the technology of this disclosure. The determination unit 81 outputs the determined second focus position FP2 to the focus lens drive control unit 82.

[0068] The setting conditions 76 are input to the determination unit 81. The determination unit 81 also receives the shooting preparation instruction signal SP and the shooting start instruction signal SS from the release button 17. The shooting preparation instruction signal SP is emitted from the release button 17 when it is half-pressed. The shooting start instruction signal SS is emitted from the release button 17 when it is fully pressed.

[0069] The focus lens drive control unit 82 controls the drive of the focus lens drive mechanism 28 and, consequently, the focus lens 26. Specifically, the focus lens drive control unit 82 moves the focus lens 26 from its current position CP to the second focus position FP2 determined by the determination unit 81 via the focus lens drive mechanism 28. Here, when the focus lens drive control unit 82 moves the focus lens 26, more precisely, it means that the focus lens drive control unit 82 sends a drive signal to the driver of the focus motor of the focus lens drive mechanism 28, causing the focus motor to move the focus lens 26. If the difference between the current position CP and the second focus position FP2 of the focus lens 26 is within an acceptable range, the focus lens drive control unit 82 does nothing, and the focus lens 26 is not moved.

[0070] As an example, as shown in Figure 17, the derivation unit 80 fixes the first calculation data DC1 of the focus adjustment region 65 and shifts the second calculation data DC2 of the focus adjustment region 65 by one pixel in the X direction. Each time it is shifted, it calculates the sum of squared differences between the first calculation data DC1 and the second calculation data DC2 of the focus adjustment region 65. Alternatively, instead of the sum of squared differences, the sum of absolute differences or the normalized cross-correlation may be calculated.

[0071] Graph 90 plots the shift amount of the second calculation data DC2 on the horizontal axis and the sum of squared differences on the vertical axis. In Graph 90, the correlation curve CC is a line connecting the plots of the sum of squared differences for each shift amount. In this correlation curve CC, the shift amount at which the sum of squared differences is minimized is the phase difference α.

[0072] The derivation unit 80 performs the above correlation calculation for each focus adjustment region 65. As a result, multiple correlation curves CC are obtained for each focus adjustment region 65; in this example, eight correlation curves CC are obtained. The derivation unit 80 aggregates the multiple correlation curves CC into a single correlation curve CC by means of averaging the multiple correlation curves CC. Then, it detects the phase difference α from the aggregated single correlation curve CC.

[0073] As an example, as shown in Figure 18, the setting condition 76 includes the following first and second conditions. 1. The interval between the instruction to prepare for shooting and the instruction to start shooting (IN) is less than the pre-set threshold interval (THIN). 2. The difference Δ between the current position CP of the focus lens 26 and the first focus position FP1 prior to the shooting preparation instruction is greater than or equal to the preset threshold difference THΔ.

[0074] The interval IN between the shooting preparation instruction and the shooting start instruction in the first condition is the interval from receiving the shooting preparation instruction signal SP to receiving the shooting start instruction signal SS. In other words, the interval IN is the interval between half-pressing and fully pressing the release button 17. Therefore, when the interval IN in the first condition is less than the threshold interval THIN, it means that the interval between half-pressing and fully pressing the release button 17 is extremely short. Hereafter, when the interval IN in the first condition is less than the threshold interval THIN, it will be referred to as "single-press".

[0075] The difference Δ between the current position CP of the focus lens 26 and the first focused position FP1 in the second condition is the so-called defocus amount. The larger the difference Δ, the more out of focus the image is. Therefore, when the difference Δ in the second condition is greater than or equal to the threshold difference THΔ, it means that the image is significantly out of focus. Hereafter, when the difference Δ in the second condition is greater than or equal to the threshold difference THΔ, it will be referred to as "severe out of focus".

[0076] Figures 19, 22, and 23 below illustrate the processing involved in continuous shooting in continuous mode and release priority mode.

[0077] As an example, as shown in Figure 19(A), if the interval IN between the shooting preparation instruction and the shooting start instruction is greater than or equal to the threshold interval THIN, and the press is not made in one continuous motion, i.e., if the first condition of setting condition 76 is not met, then sufficient time can be secured for the shooting preparation process after receiving the shooting preparation instruction signal SP. The shooting preparation process begins with the movement of the focus lens 26 to the second focus position FP2 immediately after receiving the shooting preparation instruction signal SP, and involves at least one focus control (derivation of the first focus position FP1, determination of the second focus position FP2, and movement of the focus lens 26 to the second focus position FP2). In this case, since the focus lens 26 has moved to the second focus position FP2 when the shooting start instruction signal SS is received, continuous shooting image recording begins immediately after receiving the shooting start instruction signal SS.

[0078] On the other hand, as shown in (B), if the interval IN between the shooting preparation instruction and the shooting start instruction is less than the threshold interval THIN and the button is pressed in one go, that is, if the first condition of setting condition 76 is met, sufficient time cannot be secured for the shooting preparation process. For this reason, continuous shooting starts before the movement of the focus lens 26 to the second focus position FP2 immediately after receiving the shooting preparation instruction signal SP is completed. In other words, the movement of the focus lens 26 to the second focus position FP2 immediately after receiving the shooting preparation instruction signal SP is taken up by continuous shooting. In this case, the focus lens 26 may be in a position far from the second focus position FP2 when the shooting start instruction signal SS is received. For this reason, the images of the continuous shooting recorded immediately after receiving the shooting start instruction signal SS may be blurry.

[0079] Here, we illustrate a scenario where significant blurring occurs, as shown in Figure 20. Specifically, (A) shows the state where the focus is on the distant mountain 95. From this state shown in (A), if the subject is switched from the distant mountain 95 to the foreground person 96, as shown in (B), the distance between the imaging device 10 and the subject changes significantly. When the distance between the imaging device 10 and the subject changes significantly, the difference Δ between the current position CP of the focus lens 26 and the first focus position FP1 becomes very large, resulting in significant blurring. In the case of significant blurring, the waveform of the correlation curve CC obtained by the correlation calculation of the first calculation data DC1 and the second calculation data DC2 becomes distorted. Therefore, the phase difference α detected from the correlation curve CC, and consequently the derivation accuracy of the first focus position FP1, decreases. Note that although we have illustrated the case of switching from a distant to a foreground, the same applies when switching from a foreground to a distant view.

[0080] As an example, as shown in Figure 21, in continuous shooting, the determination unit 81 determines the second focus position FP2 as follows. That is, if continuous mode and release priority mode are set (YES in steps ST1201 and ST1202), the interval IN between the shooting preparation instruction and the shooting start instruction is a single press less than the threshold interval THIN (YES in step ST1203), and furthermore, the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is greater than or equal to the threshold difference THΔ, resulting in a large blur (YES in step ST1204), the determination unit 81 does not use the first focus position FP1 obtained before the shooting preparation instruction, but instead uses the first focus position FP1 obtained after the shooting start instruction to determine the second focus position FP2 after the shooting start instruction (step ST1205).

[0081] On the other hand, if single mode is set (NO in step ST1201), or if focus priority mode is set (NO in step ST1202), the determination unit 81 uses the first focus position FP1 acquired before the shooting preparation instruction to determine the second focus position FP2 after the shooting start instruction (step ST1206). Also, if the interval IN between the shooting preparation instruction and the shooting start instruction is greater than or equal to the threshold interval THIN and it is not a single press (NO in step ST1203), or if the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is less than the threshold difference THΔ and there is no significant blur (NO in step ST1204), the determination unit 81 uses the first focus position FP1 acquired before the shooting preparation instruction to determine the second focus position FP2 after the shooting start instruction (step ST1206).

[0082] Figure 22 shows the transitions of the first focus position FP1, the second focus position FP2, and the current position CP of the focus lens 26 in a conventional example. On the other hand, Figure 23 shows the transitions of the first focus position FP1, the second focus position FP2, and the current position CP of the focus lens 26 in this example. Both Figures 22 and 23 show the case of continuous shooting in continuous mode and release priority mode with a single press and large bokeh. Here, the difference Δ is the difference between the current position CP of the focus lens 26 and the first focus position FP1 in the through image output processing immediately before the shooting preparation instruction is given.

[0083] In Figures 22 and 23, the process is the same up to the point where, immediately after receiving the shooting preparation instruction signal SP, the focus lens 26 is moved to the second focus position FP2 determined immediately before receiving the shooting preparation instruction signal SP. Subsequently, in the conventional example shown in Figure 22, the determination unit 81 determines the second focus position FP2 for several frames after the shooting start instruction, using the first focus position FP1 acquired after the shooting start instruction, as well as the first focus position FP1 acquired before the shooting preparation instruction. Specifically, the determination unit 81 determines the second focus position FP21 immediately after the shooting start instruction using the first focus positions FP11, FP12, and FP13 acquired before the shooting preparation instruction, and the first focus position FP14 acquired after the shooting start instruction. Furthermore, the determination unit 81 determines the second focus position FP22 using the first focus positions FP12 and FP13 acquired before the shooting preparation instruction, and the first focus positions FP14 and FP15 acquired after the shooting start instruction. Furthermore, the determination unit 81 determines the second focus position FP23 using the first focus position FP13 acquired before the shooting preparation instruction and the first focus positions FP14, FP15, and FP16 acquired after the shooting start instruction. Incidentally, the determination unit 81 determines the second focus position FP24 of the next frame using the first focus positions FP14, FP15, FP16, and FP17 acquired after the shooting start instruction.

[0084] The first focus position FP1 changes from the near-field first focus positions FP11, FP12, and FP13 to the far-field first focus position FP14. This is because the accuracy of deriving the first focus position FP1 improved with the movement of the focus lens 26 to the second focus position FP2, allowing the original far-field first focus position FP1 to be derived. Therefore, based on the first focus positions FP11, FP12, and FP13 acquired before the shooting preparation instruction and the first focus position FP14 acquired after the shooting start instruction, it is mistakenly perceived that the subject has moved from the near-field to the far-field. As a result, the second focus position FP21 is shifted to the far-field side compared to the corresponding first focus position FP14. For the same reason, the second focus positions FP22 and FP23 are also shifted to the far-field side compared to the corresponding first focus positions FP15 and FP16. Images recorded when the focus lens 26 is moved to these shifted second focus positions FP21, FP22, and FP23 will be blurred.

[0085] On the other hand, in Figure 23 of this example, the determination unit 81 determines the second focus position FP21 for the first frame after recording the image immediately following the instruction to start shooting, using the first focus position FP11 acquired immediately after recording the image. Furthermore, for the following few frames, the determination unit 81 determines the second focus position FP2 using only the first focus position FP1 acquired after the instruction to start shooting, without using the first focus position FP1 acquired before the instruction to prepare for shooting. Specifically, the determination unit 81 determines the second focus position FP22 using the first focus positions FP11 and FP12 acquired after the instruction to start shooting. The determination unit 81 also determines the second focus position FP23 using the first focus positions FP11, FP12, and FP13 acquired after the instruction to start shooting. The determination unit 81 determines the second focus position FP24 using the first focus positions FP11, FP12, FP13, and FP14 acquired after the instruction to start shooting. Incidentally, the second focus position FP25 of the next frame is determined by the determination unit 81 using the first focus positions FP12, FP13, FP14, and FP15 acquired after the shooting start instruction. In this example, the second focus position FP2 is determined using the first focus position FP1 acquired after the shooting start instruction, but this is not limited to this. The second focus position FP2 may also be determined using the first focus position FP1 acquired after the shooting preparation instruction (the first focus position FP1 acquired between the shooting preparation instruction and the shooting start instruction).

[0086] The time when the first focus positions FP11, FP12, FP13, FP14, and FP15 are obtained is an example of a "first time point" in relation to the technology of this disclosure. Similarly, the time when the second focus positions FP21, FP22, FP23, FP24, and FP25 are determined is an example of a "second time point" in relation to the technology of this disclosure. Thus, the first time point related to the first focus position FP1 and the second time point related to the second focus position FP2, when the shooting preparation instruction is received and the setting conditions 76 are met, occur after the shooting preparation instruction.

[0087] In this example, the first focus position FP1, acquired before the shooting preparation instruction, is not used to determine the second focus position FP2 after the shooting start instruction. Therefore, unlike in conventional examples, there is no misrecognition that the subject has moved from the foreground to the background, and the position of the subject can be correctly recognized. As a result, the second focus positions FP22, FP23, and FP24 almost coincide with the corresponding first focus positions FP12, FP13, and FP14. Images recorded when the focus lens 26 is moved to these second focus positions FP22, FP23, and FP24 are in focus.

[0088] Next, the operation of the above configuration will be explained with reference to the flowchart shown in Figure 24 as an example. As shown in Figure 15, the CPU 71 of the control unit 32 functions as a focus control unit 78 when the operation program 75 is activated. The focus control unit 78 includes a derivation unit 80, a determination unit 81, and a focus lens drive control unit 82.

[0089] In still image shooting mode, after the user half-presses the release button 17, if the full-press operation is continued for a predetermined time or longer, continuous shooting mode is activated. Under the control of the control unit 32, the image sensor 19 performs an operation to accumulate signal charge according to the subject light. Subsequently, an operation to read out the image signal 57 according to the signal charge is performed. The image signal 57 is stored in the image memory 41 via the image input controller 40. After various image processing is performed by the image processing unit 42, the image signal 57 is written back to the image memory 41.

[0090] In the focus control unit 78, calculation data DC is read from the image memory 41 to the derivation unit 80 (step ST100). Then, as shown in Figure 17, the derivation unit 80 detects the phase difference α from the calculation data DC of the focus adjustment region 65, and derives the first focus position FP1 from the phase difference α (step ST110). The first focus position FP1 is output from the derivation unit 80 to the determination unit 81. In addition, the focus control unit 78 derives the current position CP of the focus lens 26 based on the drive amount 85 of the focus motor from the focus lens drive mechanism 28.

[0091] As shown in Figure 21, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 (step ST120). Specifically, if continuous mode and release priority mode are set, the interval IN between the shooting preparation instruction and the shooting start instruction is a single press less than the threshold interval THIN, and the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is greater than or equal to the threshold difference THΔ, then the determination unit 81 determines the second focus position FP2 after the shooting start instruction using the first focus position FP1 acquired after the shooting start instruction, without using the first focus position FP1 acquired before the shooting preparation instruction. On the other hand, if single mode is set, if focus priority mode is set, if the interval IN between the shooting preparation instruction and the shooting start instruction is greater than or equal to the threshold interval THIN and not a single press, and if the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is less than the threshold difference THΔ and there is no significant blur, the determination unit 81 determines the second focus position FP2 after the shooting start instruction using the first focus position FP1 acquired before the shooting preparation instruction. The second focus position FP2 is output from the determination unit 81 to the focus lens drive control unit 82.

[0092] Under the control of the focus lens drive control unit 82, the focus lens 26 is moved to the second focus position FP2 (step ST130).

[0093] As described above, the imaging device 10 includes a determination unit 81. In continuous shooting, the determination unit 81 uses the first focus position FP1 of the focus lens 26 at the first time point to determine the second focus position FP2 of the focus lens 26 at a second time point after the first time point. The determination unit 81 receives a shooting preparation instruction, and if the setting conditions 76 are met, it uses the first focus position FP1 acquired after the shooting preparation instruction to determine the second focus position FP2. This makes it possible to improve the reliability of the second focus position FP2 of the focus lens 26 determined in continuous shooting.

[0094] As shown in Figure 23, the first and second time points after receiving the shooting preparation instruction and meeting the setting conditions 76 occur after the shooting start instruction. Therefore, it is possible to prevent misrecognition of the subject's position caused by the first focus position FP1 acquired before the shooting preparation instruction, and to correctly recognize the subject's position. As a result, in-focus images can always be obtained during continuous shooting.

[0095] Furthermore, as shown in Figure 23, the determination unit 81 receives a shooting preparation instruction, and if the setting conditions 76 are met, it determines the second focus position FP2 without using the first focus position FP1 acquired before the shooting preparation instruction. Because it does not use the first focus position FP1 acquired before the shooting preparation instruction, which has relatively low derivation accuracy, the prediction accuracy of the second focus position FP2 can be improved. This prevents misrecognition of the subject's position caused by the first focus position FP1 acquired before the shooting preparation instruction, and allows for correct recognition of the subject's position. As a result, in-focus images can always be obtained during continuous shooting.

[0096] As shown in Figure 18, setting condition 76 is that the interval IN between the shooting preparation instruction and the shooting start instruction is less than the preset threshold interval THIN. Also, setting condition 76 is that the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is greater than or equal to the preset threshold difference THΔ. Therefore, it is possible to prevent misrecognition of the subject's position that occurs when the interval IN is less than the threshold interval THIN and the camera is pressed all at once, and the difference Δ is greater than or equal to the threshold difference THΔ, resulting in a large amount of blur.

[0097] As shown in Figure 13, the control unit 32 performs a through-image output process that outputs a through-image of the subject, deriving at least a first focus position FP1, but without moving the focus lens 26 to the second focus position FP2. As shown in Figure 23, the difference Δ is the difference between the current position CP of the focus lens 26 and the first focus position FP1 in the through-image output process immediately before the shooting preparation instruction is given. Therefore, it is possible to determine whether the first focus position FP1 immediately before the shooting preparation instruction, which is related to the determination of the second focus position FP2, was derived under a state of great blur.

[0098] As shown in Figure 21, if the interval IN between the shooting preparation instruction and the shooting start instruction is greater than or equal to a preset threshold interval THIN, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction. If the interval IN is greater than or equal to the threshold interval THIN and the instruction is not pressed in one go, as shown in Figure 19(A), sufficient time can be secured for the shooting preparation process, and the focus can be set before the shooting start instruction. Therefore, even if the second focus position FP2 is determined using the first focus position FP1 acquired before the shooting preparation instruction, there will be no misrecognition of the subject's position caused by the first focus position FP1 acquired before the shooting preparation instruction.

[0099] Furthermore, as shown in Figure 21, if the difference Δ between the current position CP of the focus lens 26 before the shooting preparation instruction and the first focus position FP1 is less than a preset threshold difference THΔ, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction. If the difference Δ is less than the threshold difference THΔ and there is no significant blurring, the derivation accuracy of the first focus position FP1 acquired before the shooting preparation instruction is relatively high. Therefore, even if the second focus position FP2 is determined using the first focus position FP1 acquired before the shooting preparation instruction, there will be no misrecognition of the subject's position caused by the first focus position FP1 acquired before the shooting preparation instruction.

[0100] As shown in Figure 11, continuous shooting has two modes: a continuous mode in which the focus lens 26 is continuously moved to a second focus position FP2 that is output in a time series, and a single mode in which the focus lens 26 is fixed at a single second focus position FP2. As shown in Figure 21, when the setting condition 76 is met in continuous mode, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired after the shooting start instruction, without using the first focus position FP1 acquired before the shooting preparation instruction. On the other hand, when in single mode, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction. In single mode, the focus lens 26 is moved to a single second focus position FP2 and that state is maintained, so there is no problem in determining the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction.

[0101] As shown in Figure 12, continuous shooting has two modes: a release priority mode that prioritizes the operation of the release button 17 over the focus state of the focus lens 26, and a focus priority mode that prioritizes the focus state of the focus lens 26 over the operation of the release button 17. As shown in Figure 21, when the release priority mode satisfies the setting condition 76, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired after the shooting start instruction, without using the first focus position FP1 acquired before the shooting preparation instruction. On the other hand, when the focus priority mode is selected, the determination unit 81 determines the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction. In the case of focus priority mode, continuous shooting starts after focusing, so there is no problem in determining the second focus position FP2 using the first focus position FP1 acquired before the shooting preparation instruction.

[0102] As shown in Figure 15, the shooting preparation instruction is given in response to a half-press of the release button 17, and the shooting start instruction is given in response to a full-press of the release button 17. Therefore, the shooting preparation instruction and the shooting start instruction can be given easily.

[0103] As an example, consider the case where the imaging device 10 is equipped with a hold function for the second focus position FP2, as shown in Figure 25. The hold function treats abrupt changes in the first focus position FP1 as a derivation error and holds the second focus position FP2 at the value of the first focus position FP1 before the change. Then, when it is determined that the change in the first focus position FP1 has stopped, the hold on the second focus position FP2 is released. In this case, there is a high possibility that the position of the subject has changed between the non-hold state A before the hold state and the non-hold state B after transitioning from the hold state. Therefore, if the second focus position FP2 is determined in non-hold state B using the first focus position FP1 acquired in non-hold state A, there is a risk of misidentifying the position of the subject, as shown by the dashed-dotted line in the prediction curve, similar to the case shown in Figure 22.

[0104] Therefore, in non-hold state B, the second focus position FP2 is determined without using the first focus position FP1 acquired in non-hold state A. This prevents misrecognition of the subject's position and allows for correct recognition of the subject's position. As a result, even in non-hold state B, which is a transition from hold state, a focused image can be acquired.

[0105] Instead of the first focus position FP1, the difference Δ between the current position CP of the focus lens 26 and the first focus position FP1 may be derived as information regarding the first focus position FP1.

[0106] In the through-image output processing, the system may be configured to allow switching between two modes: one in which at least a first focus position FP1 is derived but the focus lens 26 is not moved to a second focus position FP2, and another in which the first focus position FP1 is derived, the second focus position FP2 is determined, and the focus lens 26 is moved to the second focus position FP2. Even in the latter mode, if the release button 17 is half-pressed immediately after a large change in the distance between the imaging device 10 and the subject, the difference Δ between the current position CP of the focus lens 26 and the first focus position FP1 may be greater than or equal to the threshold difference THΔ. For this reason, the technology of this disclosure can also be applied to the latter mode.

[0107] The imaging device relating to the technology disclosed herein is not limited to the digital camera exemplified, but may also be a video camera, surveillance camera, smartphone, or tablet device.

[0108] In the above embodiment, each processing unit, such as the image processing unit 42, display control unit 45, instruction receiving unit 47, focus control unit 78, output unit 80, determination unit 81, and focus lens drive control unit 82, is executed on any computer. Furthermore, any computer may execute these processes using a processor as hardware, a program as software, or a combination thereof. In this case, the processor is configured to work in cooperation with the program to execute the various processes in the above embodiment and can function as one of the units or means in the above embodiment. Also, the execution order of the processor's processes is not limited to the order described and may be changed as appropriate. Any computer may be a general-purpose computer, a computer designed for a specific application, a workstation, or any other system capable of executing each of the processes.

[0109] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of the example CPU 71, or programmable logic devices such as an MPU (Micro Processing Unit), FPGA (Field Programmable Gate Array), dedicated circuits for executing specific processes such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, these multiple hardware components may reside in physically separate devices or in the same device. Also, in any embodiment, the order of each process performed by the processor is not limited to the order described above and may be changed as appropriate. The hardware is composed of electrical circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0110] Furthermore, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a set of program modules, each function of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage devices). The program may be divided and stored on multiple non-temporary computer-readable media located in physically separate devices. Program code or code segments may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. Program code or code segments may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents.

[0111] From the above description, the technology described in the following supplementary information can be understood.

[0112] [Additional note 1] An imaging device that, in continuous shooting, uses information regarding the first focus position of the focus lens at a first time point to determine the second focus position of the focus lens at a second time point after the first time point, Equipped with a processor, The aforementioned processor, Upon receiving a first imaging instruction and meeting pre-set conditions, the second focus position is determined using information regarding the first focus position acquired after the first imaging instruction. Imaging device. [Additional note 2] The imaging apparatus according to Appendix 1, wherein the first time point and the second time point, when the first imaging instruction is received and the conditions are met, are after the first imaging instruction. [Additional note 3] The aforementioned processor, The imaging apparatus according to Appendix 2, which, upon receiving the first imaging instruction and if the above conditions are met, determines the second focus position without using the information regarding the first focus position acquired prior to the first imaging instruction. [Additional note 4] The imaging apparatus according to any one of the appendix items 1 to 3, wherein the interval between the first imaging instruction and the second imaging instruction which occurs after the first imaging instruction is less than a preset threshold interval. [Additional note 5] The imaging apparatus according to any one of the appendix items 1 to 4, wherein the difference between the position of the focus lens before the first imaging instruction and the first focus position is greater than or equal to a preset threshold difference. [Additional note 6] The aforementioned processor, A through-image output process that outputs a through-image of a subject, wherein at least information regarding the first focus position is derived, but the focus lens is not moved to the second focus position. The imaging apparatus according to Appendix 5, wherein the difference is the difference between the position of the focus lens and the first focus position in the through-image output processing immediately before the first imaging instruction is given. [Additional note 7] The aforementioned processor, The imaging apparatus according to any one of the appendix items 1 to 6, wherein if the interval between the first imaging instruction and the second imaging instruction which occurs after the first imaging instruction is greater than or equal to a preset threshold interval, the second focusing position is determined using information about the first focusing position acquired before the first imaging instruction. [Additional note 8] The aforementioned processor, The imaging apparatus according to any one of the appendix items 1 to 6, wherein if the difference between the position of the focus lens prior to the first imaging instruction and the first focus position is less than a preset threshold difference, the second focus position is determined using the information regarding the first focus position acquired prior to the first imaging instruction. [Additional note 9] The aforementioned processor, The imaging apparatus according to any one of the appendix items 1 to 6, wherein if the interval between the first imaging instruction and the second imaging instruction that occurs after the first imaging instruction is greater than or equal to a preset threshold interval, and if the difference between the position of the focus lens before the first imaging instruction and the first focus position is less than a preset threshold difference, the second focus position is determined using information about the first focus position obtained before the first imaging instruction. [Additional Note 10] The continuous shooting mode includes a continuous mode in which the focus lens is continuously moved to the second focus position, which is output in a time series, and a single mode in which the focus lens is fixed to one of the second focus positions. The aforementioned processor, If the conditions are met in the continuous mode, the second focus position is determined using the information regarding the first focus position acquired after the second imaging instruction, which is later than the first imaging instruction, without using the information regarding the first focus position acquired before the first imaging instruction. In the case of the single mode, the imaging device according to any one of the appendix items 1 to 9 determines the second focus position using the information regarding the first focus position acquired before the first imaging instruction. [Additional Note 11] The continuous shooting mode includes a release priority mode that prioritizes the operation of the release button over the focus state of the focus lens, and a focus priority mode that prioritizes the focus state of the focus lens over the operation of the release button. The aforementioned processor, If the above conditions are met in the release priority mode, the second focus position is determined using the information regarding the first focus position acquired after the second imaging instruction, which is later than the first imaging instruction, without using the information regarding the first focus position acquired before the first imaging instruction. The imaging device according to any one of the appendix items 1 to 10, which, in the case of the focus priority mode, determines the second focus position using the information regarding the first focus position acquired before the first imaging instruction. [Additional Note 12] The first imaging instruction is an instruction corresponding to a half-press operation of the release button. The imaging device according to any one of the appendices 1 to 11, wherein the second imaging instruction, which occurs after the first imaging instruction, corresponds to the full pressing of the release button.

[0113] The technology of this disclosure can be appropriately combined with the various embodiments and / or variations described above. Furthermore, it is understood that various configurations can be adopted without departing from the spirit of the invention, and the invention is not limited to the embodiments described above. In addition, the technology of this disclosure extends not only to programs, but also to storage media for non-temporarily storing programs, and to computer program products containing programs.

[0114] The descriptions and illustrations presented above are detailed explanations of the technical aspects of this disclosure and are merely examples of the technical aspects. For example, the above descriptions of the structure, function, operation, and effect are examples of the structure, function, operation, and effect of the technical aspects of this disclosure. Therefore, it goes without saying that you may delete unnecessary parts, add new elements, or replace elements in the descriptions and illustrations presented above, as long as you do not deviate from the essence of the technical aspects of this disclosure. Furthermore, in order to avoid confusion and facilitate understanding of the technical aspects of this disclosure, explanations of common technical knowledge and the like that do not require special explanation to enable the implementation of the technical aspects of this disclosure have been omitted from the descriptions and illustrations presented above.

[0115] In this specification, "A and / or B" is synonymous with "at least one of A and B." That is, "A and / or B" means that it may be A alone, or B alone, or a combination of A and B. Furthermore, in this specification, the same concept as "A and / or B" applies when expressing three or more things linked by "and / or."

[0116] All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. [Explanation of Symbols]

[0117] 10 Imaging device 11. Main unit of the device 12 Front 13 Imaging lens 14 Back 15 LCD monitors 16 Top surface 17 Power switch integrated release button (release button) 18. Base 19 Image sensor 20 Imaging surface 25 Objective lens 26 Focus Lens 27 Zoom Lens 28 Focus lens drive mechanism 29. Zoom lens drive mechanism 30 aperture 31 Aperture opening adjustment mechanism 32 Control Unit 33 Operation section 34 Image sensor driver 35 shutters 36 Shutter drive mechanism 40 Image Input Controller 41 Image memory 42 Image Processing Unit Bus lines 43 and 73 44 VRAM 45 Display Control Unit 46 Media Controllers 47 Instruction Reception Department 48 memory cards 49 Touch panel 55 Photoelectric conversion unit 56 pixels 56N Standard Pixels 56P Pixels for Phase Difference Detection 57 Image signal 57N signal for image generation 57P calculation signal 60 Microlenses 61 Color Filters 62 Photoelectric conversion element 63 Light-shielding material 65 Region for deriving the first focus position (focus adjustment region) 70 storage 71 CPU 72 memory 75 Operating Program 76 Setting conditions 78 Focusing Control Unit 80 Derivation part 81 Decision Section 82 Focus lens drive control unit 85 Drive amount 90 Graphs 95 mountains 96 People 561P First phase difference detection pixel 562P Second phase difference detection pixel 571P 1st calculation signal 572P 2nd calculation signal α phase difference Δ difference CC Correlation Curve CP focus lens position (current position) DC calculation data DC1 Data for First Calculation DC2 Second Calculation Data FP1, FP11~FP17 1st focus position FP2, FP21~FP25 2nd focus position IN interval OA optical axis SP (Special Program) Shooting Preparation Instruction Signal SS (Shot Shooting) Start Instructor Signal ST100, ST110, ST120, ST130, ST1201, ST1202, ST1203, ST1204, ST1205, ST1206 steps THΔ threshold difference THIN threshold interval

Claims

1. An imaging device that, in continuous shooting, uses information regarding the first focus position of the focus lens at a first time point to determine the second focus position of the focus lens at a second time point after the first time point, Equipped with a processor, The aforementioned processor, Upon receiving a first imaging instruction and meeting pre-set conditions, the second focus position is determined using information regarding the first focus position acquired after the first imaging instruction. Imaging device.

2. The imaging apparatus according to claim 1, wherein the first time point and the second time point when the first imaging instruction is received and the conditions are met are later than the first imaging instruction.

3. The aforementioned processor, The imaging apparatus according to claim 2, which, upon receiving the first imaging instruction and if the above conditions are met, determines the second focus position without using the information regarding the first focus position obtained prior to the first imaging instruction.

4. The imaging apparatus according to claim 1, wherein the condition is that the interval between the first imaging instruction and the second imaging instruction which occurs after the first imaging instruction is less than a preset threshold interval.

5. The imaging apparatus according to claim 1, wherein the condition is that the difference between the position of the focus lens before the first imaging instruction and the first focus position is greater than or equal to a preset threshold difference.

6. The aforementioned processor, A through-image output process that outputs a through-image of a subject, wherein at least information regarding the first focus position is derived, but the focus lens is not moved to the second focus position. The imaging apparatus according to claim 5, wherein the difference is the difference between the position of the focus lens and the first focus position in the through image output processing immediately before the first imaging instruction is given.

7. The aforementioned processor, The imaging apparatus according to claim 1, wherein if the interval between the first imaging instruction and the second imaging instruction which occurs after the first imaging instruction is greater than or equal to a preset threshold interval, the second focusing position is determined using information about the first focusing position acquired before the first imaging instruction.

8. The aforementioned processor, The imaging apparatus according to claim 1, wherein if the difference between the position of the focus lens prior to the first imaging instruction and the first focus position is less than a preset threshold difference, the second focus position is determined using information about the first focus position acquired prior to the first imaging instruction.

9. The aforementioned processor, The imaging apparatus according to claim 1, wherein if the interval between the first imaging instruction and the second imaging instruction that occurs after the first imaging instruction is greater than or equal to a preset threshold interval, and if the difference between the position of the focus lens before the first imaging instruction and the first focus position is less than a preset threshold difference, the second focus position is determined using information about the first focus position obtained before the first imaging instruction.

10. The continuous shooting mode includes a continuous mode in which the focus lens is continuously moved to the second focus position, which is output in a time series, and a single mode in which the focus lens is fixed to one of the second focus positions. The aforementioned processor, If the conditions are met in the continuous mode, the second focus position is determined using the information regarding the first focus position acquired after the second imaging instruction, which is after the first imaging instruction, without using the information regarding the first focus position acquired before the first imaging instruction. The imaging apparatus according to claim 1, wherein, in the case of the single mode, the second focus position is determined using information regarding the first focus position acquired before the first imaging instruction.

11. The continuous shooting mode includes a release priority mode that prioritizes the operation of the release button over the focus state of the focus lens, and a focus priority mode that prioritizes the focus state of the focus lens over the operation of the release button. The aforementioned processor, If the above conditions are met in the release priority mode, the second focus position is determined using the information regarding the first focus position acquired after the second imaging instruction, which is later than the first imaging instruction, without using the information regarding the first focus position acquired before the first imaging instruction. The imaging apparatus according to claim 1, which, in the case of the focus priority mode, determines the second focus position using information regarding the first focus position acquired before the first imaging instruction.

12. The first imaging instruction is an instruction corresponding to a half-press operation of the release button. The imaging apparatus according to claim 1, wherein the second imaging instruction, which is performed after the first imaging instruction, is an instruction corresponding to the full pressing of the release button.

13. A method for operating an imaging device in continuous shooting, wherein information regarding the first focus position of the focus lens at a first time point is used to determine the second focus position of the focus lens at a second time point after the first time point, Upon receiving a first imaging instruction and meeting pre-set conditions, the second focusing position is determined using information regarding the first focusing position acquired after the first imaging instruction. A method for operating an imaging device, including the device itself.

14. An operating program for an imaging device that, in continuous shooting, uses information regarding the first focus position of the focus lens at a first time point to determine the second focus position of the focus lens at a second time point after the first time point, Upon receiving a first imaging instruction and meeting pre-set conditions, the second focusing position is determined using information regarding the first focusing position acquired after the first imaging instruction. An operating program for an imaging device that causes a computer to perform a process including [specific processing].

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