Exposure control device, method for operating exposure control device, storage medium, computer program product, and imaging device

Abstract

The invention provides an exposure control device capable of performing appropriate exposure control, an operation method of the exposure control device, a storage medium, a computer program product, and an imaging device. A CPU of a control unit of an imaging device includes a setting unit and a drive control unit. When the absolute value of the difference between the first target exposure value of the current frame and the second target exposure value of the previous frame is greater than a first threshold value, the drive control unit starts exposure control. The setting unit acquires a second threshold value smaller than the first threshold value in response to the start of the exposure control. When the magnitude relationship between the absolute value of the difference and the second threshold value satisfies a preset condition, the drive control unit sets the threshold value compared with the absolute value of the difference to a third threshold value larger than the second threshold value, and terminates the exposure control.

Description

Technical Field

[0001] The technology of the present invention relates to an exposure control device, an operating method of the exposure control device, a storage medium, a computer program product, and a camera device.

[0002] Patent document 1 discloses an automatic exposure control device that controls the opening and closing of a lens aperture in a manner that reduces the difference between a target exposure level and the brightness information based on the opening and closing position information of the lens aperture and the brightness information passing through the lens. The automatic exposure control device disclosed in Patent document 1 includes a first control mechanism that controls the opening and closing of the lens aperture by compensating for the difference between the mechanical hysteresis of the lens aperture in the first direction and the mechanical hysteresis in the second direction by setting a control margin different from the target exposure level when the lens aperture moves in a first direction from a closed side to a released side and when the lens aperture moves in a second direction from a released side to a closed side.

[0003] Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2000-041181 Summary of the invention

[0005] One embodiment of the technology according to the present invention provides an exposure control device capable of performing appropriate exposure control, an operating method of the exposure control device, an operating program of the exposure control device, and an imaging device.

[0006] The exposure control device of the present invention performs exposure control so that the exposure value in the camera device follows the target exposure value. The exposure control device includes a processor, and the processor performs the following processing: when the absolute value of the difference between the first target exposure value of the first frame shot by the camera device and the second target exposure value of the second frame shot earlier than the first frame is greater than the first threshold, the exposure control is started; the second threshold value smaller than the first threshold value is obtained in response to the start of the exposure control; and when the magnitude relationship between the absolute value of the difference and the second threshold value becomes a predetermined condition, the threshold to be compared with the absolute value of the difference is set to a third threshold value larger than the second threshold value, and the exposure control is ended.

[0007] Preferably, the processor sets the third threshold to the same value as the first threshold.

[0008] Preferably, the processor sets the third threshold value to a value different from the first threshold value according to a condition.

[0009] Preferably, the processor sets the third threshold value to a value smaller than the first threshold value according to a condition.

[0010] Preferred conditions are conditions based on the detection results of the subject.

[0011] Preferably, when the absolute value of the difference becomes equal to or smaller than the second threshold, the processor sets the threshold to be compared with the absolute value of the difference to a third threshold greater than the second threshold, and terminates the exposure control.

[0012] The preferred processor performs the following processing: information on whether the absolute value of the difference is greater than the first threshold, the second threshold or the third threshold and is in an exposure control state where exposure control is in progress, or information on whether the absolute value of the difference is less than the first threshold, the second threshold or the third threshold and is in an exposure control end state where exposure control has been ended is stored in the storage unit for each frame.

[0013] Preferably, the processor sets the threshold for comparison with the absolute value of the difference to the first threshold or the third threshold when the state of the second frame is in the exposure control end state, and sets the threshold for comparison with the absolute value of the difference to the second threshold when the state of the second frame is in the exposure control state.

[0014] Preferably, the processor performs processing for storing the second target exposure value in the storage unit for each frame.

[0015] Preferably, when the absolute value of the difference is less than the first threshold or the third threshold and greater than the second threshold, and the positive and negative directions of the difference have been reversed for a predetermined number of frames, the processor sets the threshold for comparison with the absolute value of the difference to a third threshold that is larger than the second threshold, and terminates exposure control.

[0016] Preferably, the processor performs processing for storing the difference in the storage unit.

[0017] The processor performs the following processing: storing in the storage unit information on whether the absolute value of the difference is greater than the first threshold, the second threshold or the third threshold and is in an exposure control state in which exposure control is being performed, or information on whether the absolute value of the difference is less than the first threshold, the second threshold or the third threshold and is in an exposure control end state in which exposure control has been ended, for each frame; and storing the difference in the storage unit only when the state of the first frame is in the exposure control state.

[0018] The preferred processor performs the following processing:

[0019] The storage unit stores a history of the absolute value of the difference when the exposure control ends; and when the maximum value in the history is smaller than the second threshold value, the second threshold value is subtracted from the maximum value.

[0020] Preferably, the processor performs processing of subtracting the second threshold value from the maximum value when a preset number of records are stored in the storage unit.

[0021] Preferably, the processor does not inherit the history stored in the storage unit when receiving a preset operation command.

[0022] Preferably, the processor deletes the history from the storage unit when receiving a preset operation command.

[0023] An imaging device according to the present invention includes the above-mentioned exposure control device and an imaging element.

[0024] The working method of the exposure control device of the present invention is a working method of the exposure control device for performing exposure control so that the exposure value in the camera device follows the target exposure value, which includes the following steps: when the absolute value of the difference between the first target exposure value of the first frame shot by the camera device and the second target exposure value of the second frame shot earlier than the first frame is greater than the first threshold, starting the exposure control; obtaining the second threshold value smaller than the first threshold value in response to the start of the exposure control; and when the magnitude relationship between the absolute value of the difference and the second threshold value becomes a predetermined condition, setting the threshold to be compared with the absolute value of the difference to a third threshold value larger than the second threshold value, and ending the exposure control.

[0025] The storage medium of the present invention stores a working program of an exposure control device, which is a working program of an exposure control device for performing exposure control so that the exposure value in a camera device follows a target exposure value, and causes a computer to execute processing including the following steps: when the absolute value of the difference between a first target exposure value of a first frame captured by the camera device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold value, starting exposure control; obtaining a second threshold value smaller than the first threshold value in response to the start of exposure control; and when the magnitude relationship between the absolute value of the difference and the second threshold value becomes a pre-set condition, setting the threshold to be compared with the absolute value of the difference to a third threshold value larger than the second threshold value, and ending exposure control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a diagram showing the structure of an imaging device.

[0027] Figure 2 It is a diagram showing the detailed structure of the control unit.

[0028] Figure 3 This is a block diagram showing a processing unit of a CPU.

[0029] Figure 4 This is a diagram showing the processing of the setting unit when the state of the previous frame is the exposure control end state.

[0030] Figure 5 This is a diagram showing the processing of the setting unit when the state of the previous frame is the exposure control state.

[0031] Figure 6 This is a diagram showing the processing of the determination unit when the threshold is set to the first threshold.

[0032] Figure 7 This is a diagram showing the processing of the determination unit when the threshold is set to the first threshold.

[0033] Figure 8 This is a diagram showing the processing of the determination unit when the threshold is set to the second threshold.

[0034] Fig. 9 This is a diagram showing the processing of the determination unit when the threshold is set to the second threshold.

[0035] Fig.10 This is a diagram showing an example of a photographic scene that requires exposure control.

[0036] Fig.11 This is a graph showing changes in the first target exposure value and the second target exposure value.

[0037] Fig.12 This is a diagram showing the processing of the drive control unit when the threshold is set to the first threshold and the state of the current frame is the exposure control end state.

[0038] Fig.13 This is a diagram showing the processing of the drive control unit when the threshold is set to the first threshold and the state of the current frame is the exposure control state.

[0039] Fig.14 This is a diagram showing the processing of the drive control unit when the threshold is set to the second threshold and the state of the current frame is the exposure control end state.

[0040] Fig.15 This is a diagram showing the processing of the drive control unit when the threshold is set to the second threshold and the state of the current frame is the exposure control state.

[0041] Fig.16 This is a flowchart showing the processing procedure of the CPU.

[0042] Fig.17 This is a flowchart showing the processing procedure of the CPU.

[0043] Fig.18 It is a diagram showing changes in the first target exposure value and the second target exposure value of the comparative example.

[0044] Fig.19 This is a block diagram showing a processing unit of a CPU according to the second embodiment.

[0045] Fig. 20 This is a diagram showing the processing of the counting unit.

[0046] Fig.21 This is a diagram showing the processing of the counting unit.

[0047] Fig. 22 This is a diagram showing the processing of the counting unit.

[0048] Fig.23 This is a diagram showing the processing of the determination unit when the number of inversions is equal to or greater than the set number of frames.

[0049] Fig.24 This is a graph showing changes in the first target exposure value and the second target exposure value when the number of inversions is equal to or greater than the set number of frames.

[0050] Fig.25 This is a diagram showing the processing of the determination unit when the number of inversions is less than the set number of frames.

[0051] Fig.26 This is a diagram showing the processing of the determination unit when the current frame state is the exposure control state.

[0052] Fig. 27 This is a flowchart showing the processing procedure of the CPU in the second embodiment.

[0053] Fig.28 This is a flowchart showing the processing procedure of the CPU in the second embodiment.

[0054] Fig.29 This is a flowchart showing the processing procedure of the CPU according to the second embodiment.

[0055] Fig.30 This is a block diagram showing a processing unit of a CPU according to the third embodiment.

[0056] Fig.31 It is a diagram showing history information.

[0057] Fig.32 It is a diagram showing the processing of the RW control unit.

[0058] Fig.33 This is a diagram showing the processing of the RW control unit when the history of the absolute value of the difference when the exposure control ends is stored in a set number of copies and the maximum value in the history is smaller than the second threshold value.

[0059] Fig.34 This is a diagram showing the processing of the RW control unit when there is a command to turn off the power of the imaging device.

[0060] Fig.35 This is a flowchart showing the processing procedure of the CPU in the third embodiment.

[0061] Fig.36 This is a flowchart showing the processing procedure of the CPU in the third embodiment.

[0062] Fig.37 This is a flowchart showing the processing procedure of the CPU in the third embodiment.

[0063] Fig.38 This is a block diagram showing a processing unit of a CPU according to the fourth embodiment.

[0064] Fig.39 This is a diagram showing the processing of the setting unit in the fourth embodiment.

[0065] Fig.40 This is a diagram showing the processing of the setting unit in the fourth embodiment. DETAILED DESCRIPTION

[0066] [First embodiment]

[0067] As an example, Figure 1 As shown, the imaging device 10 is, for example, a single-lens digital camera without a reflector, and includes an imaging optical system 11 and an imaging element 12. The imaging optical system 11 includes a plurality of lenses for imaging subject light on the imaging element 12. Specifically, the imaging optical system 11 includes an objective lens 13, a focusing lens 14, and a zoom lens 15. These lenses 13 to 15 are arranged in order from the object side (subject side) toward the imaging side (imaging element 12 side). Figure 1 Although it is simplified in FIG. 1 , each lens 13 to 15 is actually a lens group formed by combining multiple lenses. The imaging optical system 11 also has an aperture 16. The aperture 16 is arranged on the imaging side closest to the imaging optical system 11. In addition, the imaging device 10 may be a type in which a lens barrel having the imaging optical system 11 and a main body having the imaging element 12 and the like built in are integrated, or a so-called lens replacement type in which the lens barrel and the main body are separated.

[0068] A focus lens driving mechanism 17 is provided in the focus lens 14, a zoom lens driving mechanism 18 is provided in the zoom lens 15, and an aperture opening adjustment mechanism 19 is provided in the aperture 16. The focus lens driving mechanism 17 includes, for example, a focus cam ring that holds the focus lens 14 and has a cam groove formed on the outer periphery; a focus motor that moves the focus cam ring along the optical axis OA by rotating the focus cam around the optical axis OA; and a driver for the focus motor. Similarly, the zoom lens driving mechanism 18 includes a zoom cam ring that holds the zoom lens 15 and has a cam groove formed on the outer periphery; a zoom motor that moves the zoom cam ring along the optical axis OA by rotating the zoom cam around the optical axis OA; and a driver for the zoom motor. The focus cam ring and the zoom cam ring can also be rotated manually from the outside of the lens barrel by the user. That is, the imaging device 10 can also perform focus adjustment and focal length change electrically by a focusing motor and a zooming motor, and can also perform focus adjustment and focal length change manually by a user.

[0069] The aperture 16 is, for example, an iris aperture, which is composed of a combination of a plurality of aperture blades. The aperture 16 adjusts the amount of light passing therethrough by opening and closing the central opening formed by the inner edges of the aperture blades by simultaneously moving the aperture blades by a cam mechanism, that is, by changing the opening (hereinafter referred to as the aperture of the aperture 16). The aperture opening adjustment mechanism 19 includes an aperture motor for opening and closing the aperture blades and a driver for the aperture motor. The aperture 16 can also be opened and closed manually by a user. That is, the imaging device 10 can also electrically adjust the aperture of the aperture 16 by the aperture motor, or can also manually adjust the aperture of the aperture 16 by a user.

[0070] The focusing motor, the zooming motor, and the diaphragm motor are, for example, stepping motors. In this case, the position of the focus lens 14 and the position of the zoom lens 15 on the optical axis OA, and the opening of the diaphragm 16 can be derived from the driving amounts of the focusing motor, the zooming motor, and the diaphragm motor. In addition, instead of providing the driving amounts of the focusing motor and the zooming motor, a position sensor may be provided to detect the position of the focus lens 14 and the position of the zoom lens 15.

[0071] The electric components such as the motors (focusing motor, zooming motor, and iris motor) or drivers of the driving mechanisms 17 to 19 are connected to the control unit 20. The electric components of the driving mechanisms 17 to 19 are driven under the control of the control unit 20. More specifically, the control unit 20 issues a driving signal corresponding to a command from a user input via the operation unit 21, and drives the electric components of the driving mechanisms 17 to 19. For example, when a command to change the angle of view to the telephoto side is input via the angle of view change switch of the operation unit 21, the control unit 20 issues a driving signal to the driver of the zoom motor of the zoom lens driving mechanism 18, and moves the zoom lens 15 to the telephoto side.

[0072] The focus motor, zoom motor, and diaphragm motor output drive amounts to the control unit 20. The control unit 20 derives the position of the focus lens 14 and the position of the zoom lens 15 on the optical axis OA and the aperture of the diaphragm 16 based on the drive amounts.

[0073] The imaging element 12 is, for example, a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor, and has an imaging surface 22 for capturing subject light. The imaging surface 22 is formed by a plurality of pixels arranged in a two-dimensional shape. The pixels accumulate signal charges corresponding to the subject light, and output image signals (voltage signals) corresponding to the signal charges. The imaging element 12 is configured so that the center of the imaging surface 22 coincides with the optical axis OA, and the imaging surface 22 is orthogonal to the optical axis OA. In addition, the "coincidence" and "orthogonality" mentioned here mean not only complete coincidence and orthogonality, but also coincidence and orthogonality including errors generally allowed in the technical field to which the technology of the present invention belongs.

[0074] An imaging element driver 23 is connected to the imaging element 12. The imaging element driver 23 is connected to the control unit 20. The imaging element driver 23 supplies a vertical scanning signal and a horizontal scanning signal to the imaging element 12 under the control of the control unit 20, thereby controlling the imaging timing based on the subject light of the imaging element 12. In addition, the imaging element driver 23 sets a gain applied to an image signal output from a pixel, and the gain corresponds to the ISO (International Organization for Standardization) sensitivity.

[0075] A shutter 24 is provided between the imaging optical system 11 and the imaging element 12. The shutter 24 is, for example, a focal plane shutter having a front curtain and a rear curtain. A shutter drive mechanism 25 is connected to the shutter 24. The shutter drive mechanism 25 includes an electromagnet and a driver thereof that hold the front curtain and the rear curtain and release the holding to move the front curtain and the rear curtain. The shutter drive mechanism 25 is driven under the control of the control unit 20 to open and close the shutter 24.

[0076] The control unit 20 is connected to each unit such as the image input controller 30, the image memory 31, and the image processing unit 32 via a bus 33. In addition to the bus 33, a VRAM (Video Random Access Memory) 34, a display control unit 35, a media controller 36, and a command receiving unit 37 are also connected. In addition, although not shown in the figure, a flash drive control unit for controlling the drive of the flash device, an external communication I / F (Interface) for communicating with an external device via a connection terminal such as a USB (Universal Serial Bus) terminal, or a wireless communication I / F are also connected to the bus 33.

[0077] Image data 75 obtained by capturing the subject light (reference Figure 3) is input from the imaging element 12 to the image input controller 30. The image input controller 30 outputs the image data 75 to the image memory 31. The image memory 31 is, for example, an SDRAM (Synchronous Dynamic Random Access Memory), and temporarily stores the image data 75.

[0078] The image processing unit 32 reads out the unprocessed image data 75 from the image memory 31. The image processing unit 32 performs various image processing on the image data 75. The various image processing are, for example, offset correction processing, sensitivity correction processing, pixel interpolation processing, white balance correction processing, gamma correction processing, demosaicing processing, brightness signal and color difference signal generation processing, outline emphasis processing, color correction processing, etc. The image processing unit 32 rewrites the image data 75 after various image processing into the image memory 31.

[0079] The image data 75 for display as a live preview image (also called a live view image), that is, the image data 75 after various image processing, is inputted from the image memory 31 to the VRAM 34. The VRAM 34 has an area for storing two consecutive frames of image data 75. The image data 75 stored in the VRAM 34 is sequentially rewritten as new image data 75. The VRAM 34 sequentially outputs the new image data 75 of the two consecutive frames of image data 75 to the display control unit 35.

[0080] The display control unit 35 has a function of a so-called video encoder that converts the image data 75 from the VRAM 34 into video data and outputs the video data to either the viewfinder monitor 38 or the rear monitor 39. Thus, the user can visually recognize the live preview image through either the viewfinder monitor 38 or the rear monitor 39. The display frame rate of the live preview image is, for example, 60 fps (frame per second).

[0081] In addition, for example, it is determined as follows whether the video data is output to the viewfinder monitor 38 or the rear monitor 39. That is, a pupil detection sensor is provided in advance on the viewfinder. When the pupil detection sensor detects that the user is looking at the viewfinder, the video data is output to the viewfinder monitor 38. On the other hand, when the pupil detection sensor detects that the user is not looking at the viewfinder, the video data is output to the rear monitor 39.

[0082] When a still image or moving image shooting start command is issued by fully pressing the release button of the operation unit 21, the image processing unit 32 compresses the image data 75 of the image memory 31. In the case of a still image, the image processing unit 32 compresses the image data 75 in, for example, the JPEG (Joint Photographic Experts Group) format. In the case of a moving image, the image processing unit 32 compresses the image data 75 in, for example, the MPEG (Moving Picture Experts Group) format. The image processing unit 32 outputs the compressed image data 75 to the media controller 36.

[0083] The media controller 36 records the compressed image data 75 from the image processing unit 32 in the memory card 40. The memory card 40 is detachably mounted in a memory card slot (not shown).

[0084] When the image playback mode is selected via the mode switching switch of the operation unit 21, the media controller 36 reads the image data 75 from the memory card 40 and outputs it to the image processing unit 32. The image processing unit 32 performs a stretching process on the image data 75 from the memory card 40. The stretched image data 75 is output to the display control unit 35. The display control unit 35 converts the image data 75 into video data and outputs it to the rear monitor 39. Thus, the user can visually recognize the playback image through the rear monitor 39.

[0085] The command receiving unit 37 receives various operation commands input from the user via the operation unit 21 and the touch panel 41 provided integrally with the rear monitor 39. The command receiving unit 37 outputs the received various operation commands to the control unit 20 through the bus 33.

[0086] As described above, the operating unit 21 includes a view angle change switch, a release button, and a mode switching switch. The release button is a push button that can perform two-stage operations: a half-press operation and a full-press operation. A still image or a moving image photography preparation command is issued by half-pressing the release button, and a still image or a moving image photography start command is issued by fully pressing the release button. In addition to these, the operating unit 21 also includes components such as a menu button for displaying various setting menus on the back monitor 39, a cross key for setting numerical values ​​and switching options, and a confirmation button for operations such as confirming settings. The touch panel 41 is overlapped on the display surface of the back monitor 39. The touch panel 41 recognizes various operation commands from the user by detecting contact with a dedicated commander such as a user's finger or a stylus.

[0087] The modes that can be switched by the mode switch include still image shooting mode, moving image shooting mode, image playback mode, and setting mode. The still image shooting mode includes a normal shooting mode for shooting a single still image, and a continuous shooting mode for shooting still images continuously at a predetermined shooting interval (e.g., a frame rate of 5fps to 10fps). The continuous shooting mode is initiated, for example, when the release button is fully pressed for a predetermined time or longer (e.g., more than 1 second). If the release button is released from being fully pressed, the continuous shooting mode ends.

[0088] As an example, Figure 2 As shown, the control unit 20 includes a storage device 50, a CPU (Central Processing Unit) 51, and a memory 52. ​​The storage device 50, CPU 51, and memory 52 are connected to each other via a bus 53. The control unit 20 is an example of an "exposure control device" and a "computer" involved in the technology of the present invention.

[0089] The storage device 50 is, for example, a nonvolatile storage device such as an EEPROM (Electrically Erasable Programmable Read-Only Memory). The storage device 50 stores various programs and various data attached to the various programs. The storage device 50 is an example of a "storage unit" involved in the technology of the present invention. In addition, FeRAM (Ferroelectric Random Access Memory) or MRAM (Magnetoresistive Random Access Memory) can be used as the storage device 50 instead of EEPROM.

[0090] The memory 52 is a working memory for the CPU 51 to perform processing. The CPU 51 loads the program stored in the storage device 50 into the memory 52 and performs processing according to the program. Thus, the CPU 51 centrally controls each part of the camera device 10. The CPU 51 is an example of a "processor" involved in the technology of the present invention. In addition, the memory 52 can be built into the CPU 51.

[0091] As an example, Figure 3 As shown, an operation program 60 is stored in the storage device 50. The operation program 60 is a program for causing the CPU 51 to perform exposure control. That is, the operation program 60 is an example of an "operation program of the exposure control device" involved in the technology of the present invention.

[0092] In addition to the work program 60, the storage device 50 also stores a second target exposure value EV2, a first threshold value TH1, a second threshold value TH2, and state information 61. The second target exposure value EV2 is an exposure value set as a target for exposure control in a past frame (here, a previous frame of the current frame). The state information 61 is information indicating whether the state of the previous frame is an exposure control state in which exposure control is performed or an exposure control end state in which exposure control is ended. The current frame is an example of the "first frame" involved in the technology of the present invention. In addition, the past frame and the previous frame are examples of the "second frame" involved in the technology of the present invention.

[0093] When the operation program 60 is started, the CPU 51 cooperates with the memory 52 and the like to function as a light measuring section 65 , a calculation section 66 , a setting section 67 , a read / write (hereinafter referred to as RW (Read Write)) control section 68 , a determination section 69 , and a drive control section 70 .

[0094] The unprocessed image data 75 of the current frame is input to the photometric unit 65 from the image memory 31. The photometric unit 65 derives a photometric value 76 indicating the overall brightness of the image indicated by the image data 75, based on the pixel values ​​of the image data 75. The photometric unit 65 outputs the photometric value 76 to the calculation unit 66. In addition, when a part of the imaging surface 22 of the imaging element 12 is set as the imaging area of ​​the image by the electronic zoom function or the electronic shake correction function, the photometric value 76 can be derived by limiting the set imaging area.

[0095] The calculation unit 66 calculates the first target exposure value EV1 based on the metered value 76. The first target exposure value EV1 is an exposure value that is a target of exposure control in the current frame. More specifically, the first target exposure value EV1 is an exposure value for making the image represented by the image data 75 have an appropriate brightness. The calculation unit 66 outputs the first target exposure value EV1 to the determination unit 69.

[0096] The setting unit 67 sets the threshold value based on the state information 61. More specifically, the setting unit 67 sets the threshold value for comparing the magnitude of the absolute value |ΔEV| (hereinafter simply referred to as the absolute value of the difference |ΔEV|) of the first target exposure value EV1 and the second target exposure value EV2 (=EV2-EV1) to one of the first threshold value TH1 and the second threshold value TH2. The setting unit 67 outputs the setting information 77 of the threshold value to the determination unit 69 and the drive control unit 70.

[0097] The RW control section 68 controls the storage of various data in the storage device 50 and the reading of various data stored in the storage device 50. For example, the RW control section 68 reads the second target exposure value EV2 from the storage device 50, and outputs the read second target exposure value EV2 to the determination section 69. Furthermore, the RW control section 68 reads the first threshold value TH1 and the second threshold value TH2 from the storage device 50, and outputs the read first threshold value TH1 and the second threshold value TH2 to the determination section 69. Furthermore, the RW control section 68 reads the state information 61 from the storage device 50, and outputs the read state information 61 to the setting section 67.

[0098] The determination unit 69 calculates the difference ΔEV based on the first target exposure value EV1 and the second target exposure value EV2. The determination unit 69 compares the absolute value of the difference |ΔEV| with the first threshold value TH1 or the second threshold value TH2. Then, based on the result, it is determined whether to perform exposure control so that the exposure value of the current frame follows the first target exposure value EV1, that is, whether the exposure control is implemented. The determination unit 69 outputs the determination information 78 indicating whether the exposure control is implemented to the drive control unit 70.

[0099] Furthermore, the determination unit 69 outputs the state information 61 to the RW control unit 68. The RW control unit 68 stores the state information 61 in the storage device 50. The state information 61 is output from the determination unit 69 to the RW control unit 68 for each frame, updated by the RW control unit 68, and stored in the storage device 50 for each frame. In addition, although not shown in the figure, the determination unit 69 also outputs the state information 61 to the drive control unit 70.

[0100] The drive control unit 70 controls the driving of the aperture opening adjustment mechanism 19, the imaging element driver 23, and the shutter driving mechanism 25. The drive control unit 70 operates when the determination information 78 indicates that the exposure control is to be performed. The drive control unit 70 adjusts the aperture opening of the aperture 16, the gain corresponding to the ISO sensitivity of the imaging element 12, and the shutter speed of the shutter 24 so that the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 becomes zero.

[0101] The drive control section 70 outputs the second target exposure value EV2 to the RW control section 68. The RW control section 68 stores the second target exposure value EV2 in the storage device 50. The second target exposure value EV2 is output from the drive control section 70 to the RW control section 68 for each frame, updated by the RW control section 68, and stored in the storage device 50 for each frame.

[0102] The light measuring section 65 , the calculation section 66 , the setting section 67 , the determination section 69 , and the drive control section 70 repeatedly perform the above-described processing for each frame when a live preview image is displayed and / or when a moving image is captured.

[0103] As an example, Figure 4 As shown in FIG. 6 , when the state of the previous frame indicated by the state information 61 is the exposure control end state, the setting unit 67 sets the threshold to the first threshold TH1. The setting unit 67 outputs setting information 77 instructing the determination unit 69 to set the threshold to the first threshold TH1. In this case, the determination unit 69 determines whether to implement exposure control by comparing the absolute value of the difference |ΔEV| with the first threshold TH1.

[0104] In contrast, as an example, Figure 5 As shown in FIG. 6 , when the state of the previous frame indicated by the state information 61 is the exposure control state, the setting unit 67 sets the threshold to the second threshold TH2. The setting unit 67 outputs setting information 77 instructing the determination unit 69 to set the threshold to the second threshold TH2. In this case, the determination unit 69 determines whether to implement exposure control by comparing the absolute value of the difference |ΔEV| with the second threshold TH2.

[0105] If the absolute value |ΔEV| of the difference between the first threshold TH1 and the second threshold TH2 is not greater than this value, exposure control is not performed, so it can be said that it is set as an insensitive zone for exposure control. Here, the second threshold TH2 is a value smaller than the first threshold TH1 (TH2<TH1). For example, the first threshold TH1 is 20 and the second threshold TH2 is 5.

[0106] As an example, Figure 6 As shown in FIG. 1 , when the threshold is set to the first threshold TH1 and the absolute value of the difference |ΔEV| is less than or equal to the first threshold TH1 (|ΔEV|≤TH1), the determination unit 69 determines that the exposure control is not to be performed, and outputs the determination information 78 indicating that the exposure control is not to be performed to the drive control unit 70. In this case, the determination unit 69 outputs the state information 61 indicating that the state of the current frame is the exposure control end state to the RW control unit 68.

[0107] In contrast, as an example, Figure 7 As shown in FIG. 1 , the threshold is set to the first threshold TH1. When the absolute value of the difference |ΔEV| is greater than the first threshold TH1 (|ΔEV|>TH1), the determination unit 69 determines that exposure control is to be performed, and outputs determination information 78 indicating the content of exposure control to the drive control unit 70. The determination unit 69 includes the difference ΔEV in the determination information 78. The threshold is set to the first threshold TH1 as follows: Figure 4 The state of the previous frame is the exposure control end state. Therefore, "performing exposure control" means starting exposure control. In this case, the determination unit 69 outputs the state information 61 indicating that the state of the current frame is the exposure control state to the RW control unit 68.

[0108] As an example, Figure 8 As shown in FIG. 1 , when the threshold is set to the second threshold TH2 and the absolute value of the difference |ΔEV| is less than or equal to the second threshold TH2 (|ΔEV|≤TH2), the determination unit 69 determines that the exposure control is not to be performed, and outputs the determination information 78 indicating that the exposure control is not to be performed to the drive control unit 70. The threshold is set to the second threshold TH2 as follows: Figure 5 The state of the previous frame shown is the exposure control state. Therefore, "not performing exposure control" means ending exposure control. In this case, the determination unit 69 outputs the state information 61 indicating that the state of the current frame is the exposure control end state to the RW control unit 68. When the absolute value of the difference |ΔEV| is less than the second threshold value TH2, it is an example of "a situation where the magnitude relationship between the absolute value of the difference and the second threshold value becomes a pre-set condition" involved in the technology of the present invention. In addition, the situation where the absolute value of the difference |ΔEV| is less than the second threshold value TH2 can also be set as "a situation where the magnitude relationship between the absolute value of the difference and the second threshold value becomes a pre-set condition".

[0109] exist Figure 8 In the next frame of the frame shown in FIG. 1 , the state indicated by the state information 61 is the exposure control end state, so as shown in FIG. Figure 4 As shown, the setting unit 67 sets the threshold to the first threshold TH1. The first threshold TH1 is a value greater than the second threshold TH2. Therefore, when the absolute value of the difference |ΔEV| becomes less than the second threshold TH2, the setting unit 67 sets the threshold greater than the second threshold TH2. That is, in the first embodiment, the first threshold TH1 is an example of the "third threshold greater than the second threshold" involved in the technology of the present invention.

[0110] In contrast, as an example, Fig. 9 As shown in FIG. 1 , the threshold is set to the second threshold TH2. When the absolute value of the difference |ΔEV| is greater than the second threshold TH2 (|ΔEV|>TH2), the determination unit 69 determines that exposure control is to be performed, and outputs determination information 78 indicating the content of exposure control to the drive control unit 70. The determination unit 69 includes the difference ΔEV in the determination information 78. As described above, Figure 5 As shown in FIG. 1 , the case where the threshold is set to the second threshold TH2 is the case where the state of the previous frame is the exposure control state. Therefore, "performing exposure control" means continuing exposure control. In this case, the determination unit 69 outputs the state information 61 indicating that the state of the current frame is the exposure control state to the RW control unit 68.

[0111] The following is a specific example for explanation. Fig.10As shown in FIG. 1 , in a photographic scene of a parent and child playing on a lawn in a park, consider a situation where the sun is hidden by clouds and then the clouds move and the sun is revealed. In this case, the metering value 76 representing the brightness of the image gradually increases. Therefore, as an example, Fig.11 As shown by the black circle in the graph of , in order to keep the image represented by the image data 75 at an appropriate brightness, the first target exposure value EV1 gradually takes lower values.

[0112] exist Fig.10 In the state where the sun is blocked by clouds as shown by the arrow above, exposure control is appropriately performed, and in the state where exposure control is terminated, the threshold is set to the first threshold TH1. Then, when the clouds move and the sun gradually appears, the first target exposure value EV1 starts to decrease, and at the same time, the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 starts to increase. And, as the difference ΔEV increases, the absolute value of the difference |ΔEV| also increases, and the absolute value of the difference |ΔEV| eventually becomes larger than the first threshold TH1.

[0113] When the absolute value of the difference |ΔEV| is larger than the first threshold value TH1, the determination unit 69 determines that exposure control is to be performed, and the drive control unit 70 starts exposure control. Thus, the exposure control state is established, and the setting unit 67 sets the threshold to the second threshold value TH2.

[0114] If it becomes Fig.10 In the state where the sun is exposed as shown by the arrow below, the metering value 76 indicating the brightness of the image is approximately constant, and the first target exposure value EV1 is approximately constant at a low value. At the same time, the difference ΔEV gradually narrows, and the absolute value of the difference |ΔEV| also decreases, and the absolute value of the difference |ΔEV| eventually becomes less than the second threshold value TH2.

[0115] When the absolute value of the difference |ΔEV| becomes less than the second threshold value TH2, the determination unit 69 determines that exposure control is not to be performed, and the drive control unit 70 ends the exposure control. Thus, the exposure control ends, and the setting unit 67 sets the threshold to the first threshold value TH1 again.

[0116] As an example, Fig.12 As shown, in the setting information 77 from the setting unit 67 that is set to the first threshold value TH1, when the state of the current frame represented by the state information 61 from the determination unit 69 is the exposure control end state, the drive control unit 70 outputs the first target exposure value EV1 calculated by the calculation unit 66 in the previous frame as the second target exposure value EV2 to the RW control unit 68.

[0117] As an example, Fig.13As shown, when the setting information 77 from the setting unit 67 is set to the first threshold value TH1, when the state of the current frame represented by the state information 61 from the determination unit 69 is the exposure control state, the drive control unit 70 outputs the first target exposure value EV1 calculated by the calculation unit 66 in the current frame as the second target exposure value EV2 to the RW control unit 68.

[0118] As an example, Fig.14 As shown, in the content where the setting information 77 from the setting unit 67 is set as the second threshold value TH2, when the state of the current frame indicated by the state information 61 from the determination unit 69 is the exposure control end state, Fig.13 Similarly to the case of , the drive control section 70 outputs the first target exposure value EV1 calculated by the calculation section 66 in the current frame to the RW control section 68 as the second target exposure value EV2.

[0119] As an example, Fig.15 As shown, in the content where the setting information 77 from the setting unit 67 is set to the second threshold value TH2, when the state of the current frame indicated by the state information 61 from the determination unit 69 is the exposure control state, Fig.13 and Fig.14 Similarly to the case of , the drive control section 70 outputs the first target exposure value EV1 calculated by the calculation section 66 in the current frame to the RW control section 68 as the second target exposure value EV2.

[0120] Next, as an example, refer to Fig.16 and Fig.17 The flowchart shown in FIG. 1 illustrates the function of the above structure. Figure 3 As shown, the CPU 51 of the control unit 20 functions as a photometric unit 65 , a calculation unit 66 , a setting unit 67 , an RW control unit 68 , a determination unit 69 , and a drive control unit 70 by activating the operation program 60 .

[0121] The unprocessed image data 75 of the current frame is input from the image memory 31 to the light measuring unit 65. Then, as shown in FIG. Fig.16 As shown, the photometric value 76 is derived in the photometric unit 65 (step ST100 ). The photometric value 76 is output from the photometric unit 65 to the calculation unit 66 .

[0122] The calculation unit 66 calculates the first target exposure value EV1 based on the light measurement value 76 (step ST105 ). The first target exposure value EV1 is output from the calculation unit 66 to the determination unit 69 .

[0123] If the calculation of the first target exposure value EV1 by the calculation unit 66 is the first time (YES in step ST110), the process transfers to Fig.17On the other hand, when the calculation of the first target exposure value EV1 calculated by the calculation unit 66 is not the first time (No in step ST110), the state information 61 is read from the storage device 50 under the control of the RW control unit 68, and the read state information 61 is output to the setting unit 67. Furthermore, under the control of the RW control unit 68, the second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 are read from the storage device 50, and the read second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 are output to the determination unit 69.

[0124] In the setting unit 67, the threshold is set according to the state information 61. That is, when the state of the previous frame indicated by the state information 61 is the exposure control end state ("Yes" in step ST115), Figure 4 As shown, the threshold is set to the first threshold TH1 (in step ST120).

[0125] The determination unit 69 calculates the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 (step ST125 ), and then compares the absolute value |ΔEV| of the difference with the first threshold value TH1 (step ST130 ).

[0126] When the absolute value of the difference |ΔEV| is less than the first threshold value TH1 (|ΔEV|≤TH1, "Yes" in step ST130), Figure 6 As shown in FIG. 1 , the determination unit 69 determines that the exposure control is not to be performed (step ST135). The determination unit 69 outputs the determination information 78 indicating that the exposure control is not to be performed to the drive control unit 70. In this case, the determination unit 69 outputs the state information 61 indicating that the exposure control is terminated to the RW control unit 68, and the state information 61 is stored in the storage device 50 under the control of the RW control unit 68 (step ST140). Fig.12 As shown, the first target exposure value EV1 of the previous frame is output from the drive control section 70 to the RW control section 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control section 68 (step ST145). Then, the process moves to the next frame.

[0127] On the other hand, when the absolute value of the difference |ΔEV| is greater than the first threshold value TH1 (|ΔEV|>TH1, "No" in step ST130), Figure 7As shown, the determination unit 69 determines that exposure control is to be performed (step ST150). The determination unit 69 outputs the determination information 78 including the difference ΔEV indicating the content of the exposure control to be performed to the drive control unit 70. Thus, the exposure control is started under the control of the drive control unit 70 (step ST155). In this case, the state information 61 indicating the content of the exposure control state is output from the determination unit 69 to the RW control unit 68, and the state information 61 is stored in the storage device 50 under the control of the RW control unit 68 (step ST160). Furthermore, as shown in FIG. Fig.13 As shown, the first target exposure value EV1 of the current frame is output from the drive control section 70 to the RW control section 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control section 68 (step ST165). Then, the process moves to the next frame.

[0128] If the state of the previous frame indicated by the state information 61 is the exposure control state ("No" in step ST115), the process transfers to Fig.17 Step ST170. That is, Figure 5 As shown, the threshold is set to the second threshold TH2.

[0129] In the determination unit 69 , the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 is calculated similarly to step ST125 (step ST175 ), and then the absolute value |ΔEV| of the difference is compared with the second threshold value TH2 (step ST180 ).

[0130] When the absolute value of the difference |ΔEV| is less than the second threshold value TH2 (|ΔEV|≤TH2, "Yes" in step ST180), Figure 8 As shown in FIG. 1 , the determination unit 69 determines that the exposure control is not to be performed (step ST185). The determination unit 69 outputs the determination information 78 indicating that the exposure control is not to be performed to the drive control unit 70. Thus, the exposure control by the drive control unit 70 is terminated (step ST190). In this case, the state information 61 indicating that the exposure control is terminated is outputted from the determination unit 69 to the RW control unit 68, and the state information 61 is stored in the storage device 50 under the control of the RW control unit 68 (step ST195). Fig.14 As shown, the first target exposure value EV1 of the current frame is output from the drive control section 70 to the RW control section 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control section 68 (step ST200). Then, the process moves to the next frame.

[0131] When the calculation of the first target exposure value EV1 calculated by the calculation unit 66 is the first time ("Yes" in step ST110), the state information 61 indicating that the exposure control is ended is output from the determination unit 69 to the RW control unit 68, and the state information 61 is stored in the storage device 50 under the control of the RW control unit 68 (step ST195). Furthermore, the first target exposure value EV1 of the current frame is output from the drive control unit 70 to the RW control unit 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control unit 68 (step ST200).

[0132] On the other hand, when the absolute value of the difference |ΔEV| is greater than the second threshold value TH2 (|ΔEV|>TH2, "No" in step ST180), Fig. 9 As shown, the determination unit 69 determines that exposure control is to be performed (step ST205). The determination unit 69 outputs the determination information 78 including the difference ΔEV indicating the content of the exposure control to the drive control unit 70. Thus, the exposure control is continued under the control of the drive control unit 70 (step ST210). In this case, the state information 61 indicating the content of the exposure control state is output from the determination unit 69 to the RW control unit 68, and the state information 61 is stored in the storage device 50 under the control of the RW control unit 68 (step ST215). Furthermore, as shown in FIG. Fig.15 As shown, the first target exposure value EV1 of the current frame is output from the drive control section 70 to the RW control section 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control section 68 (step ST200). Then, the process moves to the next frame.

[0133] As described above, the CPU 51 of the control unit 20 of the imaging device 10 includes the setting unit 67 and the drive control unit 70. The drive control unit 70 starts exposure control when the absolute value |ΔEV| of the difference between the first target exposure value EV1 of the current frame and the second target exposure value EV2 of the previous frame is greater than the first threshold value TH1. The setting unit 67 acquires the second threshold value TH2 smaller than the first threshold value TH1 in response to the start of exposure control. When the magnitude relationship between the absolute value |ΔEV| of the difference and the second threshold value TH2 meets a predetermined condition, the drive control unit 70 sets the threshold to be compared with the absolute value |ΔEV| of the difference to a third threshold value greater than the second threshold value TH2, which is set to the first threshold value TH1 in this case, and ends exposure control.

[0134] Fig.18The comparative example shows a case where the exposure control is performed while keeping the threshold at the first threshold TH1. In this case, since the first threshold TH1 is large and the insensitive zone of the exposure control is wide, the exposure control ends in the open state where the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 is large (the state where the first threshold TH1 is opened at the maximum), and there is a possibility that an image with appropriate brightness cannot be provided.

[0135] In contrast, in the imaging device 10 of the present invention, the threshold is changed to the second threshold TH2 which is smaller than the first threshold TH1 in response to the start of exposure control. Therefore, the exposure control ends in a state where the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 is greatly increased, and the possibility of a state in which an image with appropriate brightness cannot be provided can be reduced. Therefore, appropriate exposure control can be performed.

[0136] The setting unit 67 sets the first threshold TH1 as the third threshold. Therefore, the setting of the threshold can be simplified.

[0137] When the absolute value of the difference |ΔEV| becomes less than or equal to the second threshold value TH2, the drive control unit 70 ends the exposure control. Therefore, the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 in the exposure control end state is always less than or equal to the second threshold value TH2. By setting the second threshold value TH2 to an appropriate value, an image with appropriate brightness can be provided.

[0138] The determination unit 69 outputs the state information 61 indicating that the absolute value of the difference |ΔEV| is greater than the first threshold value TH1 or the second threshold value TH2 and the exposure control is being performed, or the absolute value of the difference |ΔEV| is less than the first threshold value TH1 or the second threshold value TH2 and the exposure control is completed, to the RW control unit 68. The RW control unit 68 stores the state information 61 in the storage device 50 for each frame. Therefore, it is possible to reliably grasp whether the state of the previous frame is the exposure control state or the exposure control completed state. The threshold value based on the state information 61 set by the setting unit 67 can be set accurately.

[0139] When the state of the previous frame is the exposure control end state, the setting unit 67 sets the threshold value to the first threshold value TH1. On the other hand, when the state of the previous frame is the exposure control state, the setting unit 67 sets the threshold value to the second threshold value TH2. By setting the threshold value to the first threshold value TH1 in the exposure control end state to expand the insensitive zone of exposure control, it is possible to avoid the visual angle jitter in which the exposure control is frequently performed in response to the slight change of the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 one by one. On the other hand, in the exposure control state, by setting the threshold value to the second threshold value TH2 to reduce the insensitive zone of exposure control, it is possible to reduce the possibility of reaching the exposure control end state in a state where the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 is still greatly wide.

[0140] The drive control section 70 outputs the second target exposure value EV2 to the RW control section 68. The RW control section 68 stores the second target exposure value EV2 in the storage device 50 for each frame. Therefore, the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 can be reliably calculated.

[0141] [Second embodiment]

[0142] As an example, Fig.19 As shown, in the second embodiment, in addition to the processing units 65 to 70 of the first embodiment (except the RW control unit 68 and the determination unit 69, not shown), the CPU 51 also functions as a counter unit 85. The counter unit 85 receives the first target exposure value EV1 from the calculation unit 66.

[0143] The RW control section 68 reads the second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 from the storage device 50, and outputs the read second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 to the counting section 85 and the determination section 69. In addition, the RW control section 68 reads the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 from the storage device 50, and outputs the read difference ΔEV to the counting section 85. The difference ΔEV is the difference calculated by the determination section 69 in the previous frame. Hereinafter, in order to distinguish the difference ΔEV from the difference ΔEV of the current frame, it is denoted as a difference ΔEVX.

[0144] The storage device 50 also stores the number of reversal times NR and the set number of frames SF. The number of reversal times NR is the number of times the difference ΔEV is reversed continuously in positive and negative directions. The set number of frames SF is a threshold value for comparing the number of reversal times NR and the magnitude, for example, 5 to 10. The set number of frames SF is an example of a "predetermined number of frames" involved in the technology of the present invention. The RW control unit 68 reads the number of reversal times NR and the set number of frames SF from the storage device 50, and outputs the read number of reversal times NR and the set number of frames SF to the determination unit 69.

[0145] The counting section 85 calculates the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2. The counting section 85 generates an update command signal 86 for the number of inversions NR based on the difference ΔEV of the current frame, the difference ΔEVX of the previous frame, the first threshold TH1, and the second threshold TH2. The counting section 85 outputs the update command signal 86 to the RW control section 68. The RW control section 68 updates the number of inversions NR based on the update command signal 86.

[0146] As an example, Fig. 20 As shown, when the absolute value of the difference |ΔEV| of the current frame is less than the first threshold value TH1 and greater than the second threshold value TH2 (TH2<|ΔEV|≤TH1), and when the positive and negative signs of the difference ΔEV of the current frame and the difference ΔEVX of the previous frame have been reversed, the counting unit 85 outputs an update command signal 86 instructing to increase the number of inversions NR to the RW control unit 68. The RW control unit 68 increases the number of inversions NR in accordance with the update command signal 86.

[0147] On the other hand, as an example, Fig.21 As shown in FIG. 1 , when the absolute value of the difference |ΔEV| of the current frame is less than the first threshold value TH1 and greater than the second threshold value TH2, but the difference ΔEV of the current frame is the same as the difference ΔEVX of the previous frame in sign, the counting unit 85 outputs an update command signal 86 instructing to clear the number of reversal times NR to the RW control unit 68. The RW control unit 68 clears the number of reversal times NR in response to the update command signal 86. In addition, clearing the number of reversal times NR means setting the number of reversal times NR to 0.

[0148] And, as an example, Fig. 22 As shown, even when the absolute value of the difference |ΔEV| of the current frame is larger than the first threshold value TH1 (|ΔEV|>TH1), the counter 85 outputs an update command signal 86 instructing the RW control unit 68 to clear the number of reversal times NR. The RW control unit 68 clears the number of reversal times NR in response to the update command signal 86.

[0149] As an example, Fig.23As shown, when the number of reversal times NR is greater than or equal to the set number of frames SF (NR ≥ SF), the determination unit 69 determines that exposure control is not to be performed, and outputs determination information 78 indicating that exposure control is not to be performed to the drive control unit 70.

[0150] When the number of reversal times NR becomes greater than the set number of frames SF, the state is as follows: As an example, Fig.24 As shown in FIG. 1 , in the final stage of the exposure control state, the first target exposure value EV1 and the second target exposure value EV2 continue to change slightly, and the exposure control is frequently performed in response to the changes, resulting in a state of brightness fluctuation. In this case, since oscillation occurs, the determination unit 69 determines that no further exposure control is required, and determines that no exposure control is performed. Therefore, Fig.23 The phrase “do not perform exposure control” means that exposure control is forcibly terminated.

[0151] On the other hand, as an example, Fig.25 As shown, when the number of reversal times NR is less than the set number of frames SF (NR<SF), the determination unit 69 determines that exposure control is to be performed, and outputs determination information 78 indicating the content of exposure control to the drive control unit 70. The determination unit 69 includes the difference ΔEV in the determination information 78. In this case, “performing exposure control” means continuing exposure control.

[0152] As an example, Fig.26 As shown, the determination section 69 outputs the difference ΔEVX to the RW control section 68 only when the state of the current frame indicated by the state information 61 is in the exposure control state. The RW control section 68 stores the difference ΔEVX in the storage device 50 .

[0153] As an example, refer to Figure 27 to Figure 29 The flowchart shown in the figure explains the operation of the second embodiment. The description of the same processing as the first embodiment will be omitted as much as possible, and the processing unique to the second embodiment will be mainly described.

[0154] First, if Fig. 27 As shown in FIG. 1 , when the absolute value of the difference |ΔEV| is greater than the first threshold value TH1 (“No” in step ST130), exposure control is started under the control of the drive control unit 70 (step ST155), and when the state information 61 indicating that the exposure control state is in progress is output from the determination unit 69 to the RW control unit 68 (step ST160), as shown in FIG. Fig.26 As shown, the difference ΔEVX is output from the determination unit 69 to the RW control unit 68, and the difference ΔEVX is stored in the storage device 50 under the control of the RW control unit 68 (in step ST300).

[0155] Under the control of the RW control section 68, the second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 are read out from the storage device 50, and the read out second target exposure value EV2, the first threshold value TH1, and the second threshold value TH2 are output to the counting section 85 and the determination section 69. Furthermore, under the control of the RW control section 68, the difference ΔEVX of the previous frame is read out from the storage device 50, and the read out difference ΔEVX is output to the counting section 85.

[0156] like Fig.28 As shown, when the threshold is set to the second threshold TH2 by the setting unit 67 (step ST170) and the absolute value of the difference |ΔEV| is greater than the second threshold TH2 ("No" in step ST180), in the counting unit 85, the absolute value of the difference |ΔEV| is compared with the first threshold TH1 (step ST305).

[0157] When the absolute value of the difference |ΔEV| is less than the first threshold value TH1 (|ΔEV|≤TH1, "Yes" in step ST305), the counting unit 85 further determines whether the positive and negative signs of the difference ΔEV of the current frame and the difference ΔEVX of the previous frame are reversed (step ST310).

[0158] When the sign of the difference ΔEV between the current frame and the difference ΔEVX between the previous frame has reversed (“Yes” in step ST310), Fig. 20 As shown, the counter 85 outputs the update command signal 86 for increasing the inversion number NR to the RW control unit 68 (step ST315). The RW control unit 68 increases the inversion number NR of the storage device 50 according to the update command signal 86.

[0159] Under the control of the RW control unit 68 , the number of reversal times NR and the set number of frames SF are read from the storage device 50 , and the read number of reversal times NR and the set number of frames SF are output to the determination unit 69 .

[0160] In the determination unit 69, the number of reversal times NR is compared with the set number of frames SF (step ST320). If the number of reversal times NR is greater than the set number of frames SF ("Yes" in step ST320), Fig.23 As shown, the determination unit 69 determines that exposure control is not to be performed (step ST325). The determination unit 69 outputs determination information 78 indicating that exposure control is not to be performed to the drive control unit 70. Thus, the exposure control by the drive control unit 70 is forcibly terminated (step ST330).

[0161] When the absolute value of the difference |ΔEV| is greater than the first threshold value TH1 (|ΔEV|>TH1 is "No" in step ST305), and when the difference ΔEV of the current frame and the difference ΔEVX of the previous frame are the same in sign ("No" in step ST310), the process simultaneously transfers to Fig.29 Step ST335. That is, Fig.21 and Fig. 22 As shown, the counter section 85 outputs an update command signal 86 instructing to clear the number of inversions NR to zero to the RW control section 68. The RW control section 68 clears the number of inversions NR of the storage device 50 according to the update command signal 86.

[0162] Then, exposure control is continued under the control of the drive control unit 70 (step ST340). Even when the number of reversal times NR is less than the set number of frames SF (NR<SF, "No" in step ST320), exposure control is continued under the control of the drive control unit 70 (step ST340).

[0163] In this case, the determination section 69 outputs the state information 61 of the exposure control state to the RW control section 68, and the state information 61 is stored in the storage device 50 under the control of the RW control section 68 (step ST345). Furthermore, the first target exposure value EV1 of the current frame is output from the drive control section 70 to the RW control section 68 as the second target exposure value EV2, and the second target exposure value EV2 is stored in the storage device 50 under the control of the RW control section 68 (step ST350).

[0164] And, with Fig. 27 Similarly to step ST300, the difference ΔEVX is output from the determination unit 69 to the RW control unit 68, and the difference ΔEVX is stored in the storage device 50 under the control of the RW control unit 68 (step ST355). Then, the process moves to the next frame.

[0165] Thus, in the second embodiment, when the absolute value of the difference |ΔEV| is less than the first threshold TH1 and greater than the second threshold TH2, and the positive and negative inversion of the difference ΔEV continues for the set frame number SF, the drive control unit 70 ends the exposure control.

[0166] By setting the threshold value to the relatively small second threshold value TH2, compared with the case where the threshold value is set to the first threshold value TH1, the following situation is more likely to occur. Fig.24 Therefore, in the second embodiment, when the state of the difference ΔEV being reversed in positive and negative continues for the set number of frames SF, it is determined that the angle of view fluctuation has occurred and the exposure control is forcibly terminated. Therefore, the possibility of unnecessary exposure control continuing endlessly can be reduced.

[0167] The determination unit 69 outputs the difference ΔEVX of the previous frame to the RW control unit 68. The RW control unit 68 stores the difference ΔEVX in the storage device 50. Therefore, it is possible to reliably determine whether the positive and negative signs of the difference ΔEVX of the current frame and the difference ΔEVX of the previous frame are reversed, and whether the angle of view fluctuation occurs.

[0168] The determination unit 69 stores the difference ΔEVX in the storage device 50 only when the state of the current frame indicated by the state information 61 is in the exposure control state. Therefore, only the difference ΔEVX related to whether the angle of view fluctuation occurs can be stored in the storage device 50, thereby avoiding unnecessary information from being stored in the storage device 50.

[0169] [Third Embodiment]

[0170] As an example, Fig.30 As shown in the third embodiment, the storage device 50 stores the history information 90. As an example, Fig.31 As shown, the history information 90 is a collection of the history of the absolute value |ΔEV| of the difference when the exposure control ends. The determination unit 69 outputs the absolute value |ΔEV| of the difference to the RW control unit 68. The RW control unit 68 registers the absolute value |ΔEV| of the difference in the history information 90.

[0171] The RW control unit 68 outputs the maximum value |ΔEV|max in the history of the absolute value |ΔEV| of the difference registered in the history information 90 as the second threshold value TH2 to the determination unit 69. The determination unit 69 determines whether to implement exposure control by comparing the absolute value |ΔEV| of the difference calculated from the first target exposure value EV1 and the second target exposure value EV2 with the second threshold value TH2 based on the maximum value |ΔEV|max. Hereinafter, in order to distinguish the second threshold value TH2 based on the maximum value |ΔEV|max from the default second threshold value TH2, it is denoted as TH2max.

[0172] As an example, Fig.32 As shown in FIG. 1 , when it is determined that the absolute value of the difference |ΔEV| becomes less than the second threshold value TH2 and the exposure control is not performed and the state of the previous frame becomes the exposure control end state, the determination unit 69 outputs the absolute value of the difference |ΔEV| to the RW control unit 68. The RW control unit 68 stores the absolute value of the difference |ΔEV| in the storage device 50 by registering the absolute value of the difference |ΔEV| in the history information 90.

[0173] And, as an example, Fig.33As shown, when the history of the absolute value of the difference |ΔEV| when the exposure control ends is stored in the storage device 50 in the set number SN, and the maximum value |ΔEV|max in the history of the absolute value of the difference |ΔEV| when the exposure control ends is less than the second threshold value TH2 (|ΔEV|max<TH2), the RW control unit 68 subtracts the second threshold value TH2 from the maximum value |ΔEV|max to make it the second threshold value TH2max. The RW control unit 68 outputs the second threshold value TH2max to the determination unit 69. The set number SN is, for example, 10 to 15.

[0174] When a command is issued to turn off the power of the imaging device 10 by operating the power button of the operation unit 21 by the user, the power off signal 95 is received by the command receiving unit 37. Fig.34 As shown in FIG. 1 , a power-off signal 95 is input from the command receiving unit 37 to the RW control unit 68. Receiving the power-off signal 95, the RW control unit 68 outputs a history deletion signal 96 for deleting the history of the absolute value of the difference |ΔEV| when the exposure control ends, which has been registered in the history information 90 so far. The command to turn off the power of the imaging device 10 is an example of a "preset operation command" involved in the technology of the present invention. In addition, when the power of the imaging device 10 is turned on, the RW control unit 68 restarts the history of the absolute value of the difference |ΔEV| stored in the exposure control ends state.

[0175] As an example of the effect of the third embodiment, refer to Figure 35 to Figure 37 The description of the same processing as that of the first embodiment will be omitted as much as possible, and the description will be mainly made of processing unique to the third embodiment.

[0176] First, if Fig.35 As shown in FIG. 1 , when the absolute value of the difference |ΔEV| becomes less than the second threshold value TH2 (“Yes” in step ST180), the determination unit 69 determines that the exposure control is not to be performed (in step ST185). When the exposure control performed by the drive control unit 70 is terminated (in step ST190), as shown in FIG. Fig.32 As shown, the absolute value |ΔEV| of the difference is output from the determination unit 69 to the RW control unit 68, and the absolute value |ΔEV| of the difference is stored in the storage device 50 under the control of the RW control unit 68 (in step ST400).

[0177] like Fig.36 As shown, when the state of the previous frame represented by the state information 61 is the exposure control state ("No" in step ST115), the RW control unit 68 searches whether the history of the absolute value of the difference |ΔEV| called the exposure control end state is stored in the storage device 50 in a set number SN (step ST405).

[0178] When the history of absolute values ​​of differences |ΔEV| is stored in the storage device 50 in the set number SN (YES in step ST405 ), the RW control unit 68 compares the maximum value |ΔEV|max in the history with the second threshold TH2 (step ST410 ).

[0179] When the maximum value |ΔEV|max is smaller than the second threshold value TH2 (|ΔEV|max<TH2, "Yes" in step ST410), Fig.33 As shown, the second threshold TH2 is reduced to the maximum value |ΔEV|max by the RW control unit 68 and becomes the second threshold TH2max (step ST415). Then, the threshold is set to the second threshold TH2max by the setting unit 67 (step ST420).

[0180] On the other hand, when the history of the absolute value of the difference |ΔEV| is not stored in the storage device 50 in the set number SN ("No" in step ST405), and when the maximum value |ΔEV|max is the same as the second threshold TH2 ("No" in step ST410), the threshold is set to the second threshold TH2 by the setting unit 67 instead of subtracting the second threshold TH2 from the maximum value |ΔEV|max (step ST420).

[0181] And, if Fig.37 As shown, the user operates the power button of the operation unit 21 to issue a command to turn off the power of the photographing device 10, such as Fig.34 As shown in FIG. 4 , when the power off signal 95 is input to the RW control unit 68 (“Yes” in step ST425), the RW control unit 68 outputs a history deletion signal 96. Thus, the history of the absolute value |ΔEV| of the difference when the exposure control ends, which has been registered in the history information 90 so far, is deleted (step ST430).

[0182] Thus, in the third embodiment, the RW control unit 68 stores the history of the absolute value |ΔEV| of the difference when the exposure control ends in the storage device 50. And, when the maximum value |ΔEV|max in the history record is smaller than the second threshold value TH2, the second threshold value TH2 is subtracted from the maximum value |ΔEV|max. Therefore, the second threshold value TH2 can be set to a value suitable for the photographic scene. And, the possibility of a state where the difference ΔEV between the first target exposure value EV1 and the second target exposure value EV2 is greatly increased and an image with appropriate brightness cannot be provided can be further reduced.

[0183] The RW control unit 68 performs a process of subtracting the second threshold value TH2 from the maximum value |ΔEV|max when the history of the absolute value |ΔEV| of the difference in the case of the exposure control end state is stored in the storage device 50 by the set number SN. Therefore, the effectiveness of the process of subtracting the second threshold value TH2 from the maximum value |ΔEV|max can be ensured.

[0184] When the RW control unit 68 receives a command to turn off the power of the camera device 10, the history of the absolute value of the difference |ΔEV| when the exposure control is terminated, which is stored in the storage device 50, is not inherited. More specifically, the history of the absolute value of the difference |ΔEV| when the exposure control is terminated is deleted from the storage device 50. Turning off the power of the camera device 10 indicates the end of the photography of the image in the photographic scene. Therefore, when the power of the camera device 10 is turned off, in order to re-store the history of the absolute value of the difference |ΔEV| in the next photographic scene, the history of the absolute value of the difference |ΔEV| is not inherited but deleted. In this way, the second threshold value TH2 can be set to a value that is always suitable for the photographic scene.

[0185] In addition, the preset operation command is not limited to the command to turn off the power of the camera device 10. It may be a command for zoom operation, a command to switch from a moving image shooting mode to an image playback mode, etc. Furthermore, as a method of not inheriting the history, in addition to deleting the history, a method of not treating the data stored in the storage device 50 as history may be considered.

[0186] The process of subtracting the second threshold value TH2 is not limited to one time, but may be performed multiple times. When the default second threshold value TH2 is 5, for example, the second threshold value TH2 may be reduced in multiple stages such as 5, 4, 3, ... . . .

[0187] The second frame is not limited to the previous frame before the current frame. The frame from the current frame to a predetermined number of frames before can also be set as the second frame. In this case, the second target exposure value EV2 is set to a representative value such as the average value of the second target exposure value EV2 of the collected frames.

[0188] [Fourth embodiment]

[0189] As an example, Fig.38 As shown, in the fourth embodiment, the CPU 51 of the control unit 20 includes the processing units 65 to 70 (in Fig.38In addition to the setting unit 67 and the determination unit 69 (only the setting unit 67 and the determination unit 69 are shown in the figure), the subject detection unit 100 also functions as a subject detection unit 100. The image data 75 is input to the subject detection unit 100. The subject detection unit 100 detects a person as a subject projected on the image represented by the image data 75. The subject detection unit 100 outputs a detection result 101 of the person to the setting unit 67.

[0190] The setting unit 67 receives the state information 61 from the RW control unit 68 and the detection result 101 from the subject detection unit 100. Furthermore, the setting unit 67 receives the condition 102 based on the detection result 101. The condition 102 is stored in the storage device 50, read out from the storage device 50 under the control of the RW control unit 68, and output to the setting unit 67.

[0191] In the fourth embodiment, in addition to the first threshold TH1 and the second threshold TH2, the third threshold TH3_1 and the third threshold TH3_2 can be set as thresholds. The third threshold TH3_1 and the third threshold TH3_2 are both greater than the second threshold TH2 (TH2<TH3_1, TH3_2). Furthermore, the third threshold TH3_1 is less than the first threshold TH1 (TH3_1<TH1). Furthermore, the third threshold TH3_2 is greater than the first threshold TH1 (TH1<TH3_2). For example, the first threshold TH1 is 20, the second threshold TH2 is 5, the third threshold TH3_1 is 18, and the third threshold TH3_2 is 22.

[0192] As an example, Fig.39 As shown, when the state of the previous frame indicated by the state information 61 is the exposure control end state and the detection result 101 detects a person, the setting unit 67 sets the threshold to the 3_1 threshold TH3_1 according to the condition 102 that the 3_1 threshold TH3_1 is set when the person is one person. The setting unit 67 outputs the setting information 77 instructing the determination unit 69 to set the threshold to the 3_1 threshold TH3_1. In this case, the determination unit 69 determines whether to implement exposure control by comparing the absolute value of the difference |ΔEV| and the 3_1 threshold TH3_1.

[0193] As an example, Fig.40As shown, when the state of the previous frame represented by the state information 61 is the exposure control end state and the detection result 101 detects a plurality of people, the setting unit 67 sets the threshold to the 3_2 threshold TH3_2 according to the condition 102 that the 3_2 threshold TH3_2 is set when there are multiple people. The setting unit 67 outputs the setting information 77 instructing the determination unit 69 to set the threshold to the 3_2 threshold TH3_2. In this case, the determination unit 69 determines whether to implement exposure control by comparing the absolute value of the difference |ΔEV| and the 3_2 threshold TH3_2. In addition, when the detection result 101 does not satisfy the condition 102, such as that no person is shown in the image represented by the image data 75, the setting unit 67 sets the threshold to the first threshold TH1.

[0194] Thus, in the fourth embodiment, the setting unit 67 sets the third threshold value different from the first threshold value TH1, that is, the 3rd threshold value TH3_1 or the 3rd threshold value TH3_2, according to the condition 102. Therefore, the threshold value corresponding to the condition 102 can be set.

[0195] The setting unit 67 sets the 3_1 threshold value TH3_1 which is smaller than the first threshold value TH1. Therefore, compared with the case where the first threshold value TH1 is set, the exposure control can quickly follow the change of the photographing scene.

[0196] like Fig.39 As shown in FIG. 1 , when there is only one person shown in the image represented by the image data 75, in order to make the exposure control quickly follow the change of the photographic scene corresponding to the movement of the one person, the threshold is set to the 3_1 threshold TH3_1 which is smaller than the 1st threshold TH1. Fig.40 As shown, when there are multiple persons in the image represented by the image data 75, the threshold is set to a 3_2 threshold TH3_2 greater than the 1st threshold TH1 in order not to react allergically to the change of the photographic scene corresponding to the movement of the multiple persons. In this way, if the threshold is set according to the condition 102 based on the detection result 101 of the subject detection unit 100, more appropriate exposure control can be performed.

[0197] The fourth embodiment may be implemented in combination with the second embodiment and / or the third embodiment.

[0198] The imaging device according to the technology of the present invention may be a small digital camera, a smart phone, or a tablet terminal.

[0199] In the above-mentioned embodiments, for example, various processors shown below can be used as the hardware structure of the processing unit (Processing Unit) that performs various processes such as the image processing unit 32, the display control unit 35, the command receiving unit 37, the light measuring unit 65, the calculation unit 66, the setting unit 67, the RW control unit 68, the determination unit 69, the drive control unit 70, the counting unit 85, and the subject detection unit 100. The various processors include a general-purpose processor, i.e., the CPU 51, which performs the functions of the various processing units by executing software (running program 60), and other processors whose circuit structure can be changed after manufacturing, i.e., programmable logic devices (PLDs) and / or ASICs (Application Specific Integrated Circuits) that have circuit structures specially designed to perform specific processes, i.e., dedicated circuits.

[0200] One processing unit may be composed of one of these various processors, or a combination of two or more processors of the same or different types (for example, a combination of multiple FPGAs and / or a combination of a CPU and an FPGA). Furthermore, multiple processing units may be composed of one processor.

[0201] As examples of multiple processing units composed of one processor, there are the following methods: First, as represented by computers such as client terminals and servers, a processor is composed of a combination of one or more CPUs and software, and the processor functions as multiple processing units. Second, as represented by system on chip (System On Chip: SOC), there is a method of using a processor that implements the overall function of a system including multiple processing units by a single IC (Integrated Circuit) chip. In this way, various processing units are composed of one or more of the above-mentioned processors as a hardware structure.

[0202] Furthermore, as the hardware configuration of these various processors, more specifically, a circuit (Circuitry) formed by combining circuit elements such as semiconductor elements can be used.

[0203] From the above contents, the techniques described in the following supplementary notes can be understood.

[0204] [Supplementary Item 1]

[0205] An exposure control device performs exposure control so that an exposure value in an imaging device follows a target exposure value.

[0206] The exposure control device includes a processor, and the processor performs the following processing:

[0207] starting the exposure control when an absolute value of a difference between a first target exposure value of a first frame captured by the imaging device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold;

[0208] acquiring a second threshold value smaller than the first threshold value in response to the start of the exposure control; and

[0209] When the magnitude relationship between the absolute value of the difference and the second threshold satisfies a preset condition, the threshold to be compared with the absolute value of the difference is set to a third threshold greater than the second threshold, and the exposure control is terminated.

[0210] [Supplementary Item 2]

[0211] The exposure control device according to Supplementary Item 1, wherein:

[0212] The processor sets the third threshold to the same value as the first threshold.

[0213] [Supplementary item 3]

[0214] The exposure control device according to Supplementary item 1 or 2, wherein:

[0215] The processor sets the third threshold to a value different from the first threshold according to a condition.

[0216] [Supplementary Item 4]

[0217] The exposure control device according to Supplementary Item 3, wherein:

[0218] The processor sets the third threshold to a value smaller than the first threshold based on the condition.

[0219] [Supplementary Note 5]

[0220] The exposure control device according to Supplementary item 3 or 4, wherein:

[0221] The condition is a condition based on the detection result of the object.

[0222] [Supplementary Item 6]

[0223] An exposure control device according to any one of Supplementary Items 1 to 5, wherein:

[0224] When the absolute value of the difference becomes equal to or smaller than the second threshold, the processor sets a threshold to be compared with the absolute value of the difference to the third threshold that is larger than the second threshold, and terminates the exposure control.

[0225] [Supplementary Note 7]

[0226] The exposure control device according to any one of Supplementary Items 1 to 6, wherein:

[0227] The processor performs the following processing:

[0228] Information on whether the absolute value of the difference is greater than the first threshold, the second threshold or the third threshold and is in an exposure control state in which the exposure control is being performed, or information on whether the absolute value of the difference is less than the first threshold, the second threshold or the third threshold and is in an exposure control end state in which the exposure control has been ended, is stored in the storage unit for each frame.

[0229] [Supplementary Item 8]

[0230] The exposure control device according to Supplementary Item 7, wherein:

[0231] The processor performs the following processing:

[0232] When the second frame is in the exposure control end state, setting the threshold to be compared with the absolute value of the difference to the first threshold or the third threshold; and

[0233] When the second frame is in the exposure control state, a threshold to be compared with the absolute value of the difference is set as the second threshold.

[0234] [Supplementary Item 9]

[0235] The exposure control device according to Supplementary Item 7 or Supplementary Item 8, wherein:

[0236] The processor performs a process of storing the second target exposure value in the storage unit for each frame.

[0237] [Supplementary Item 10]

[0238] An exposure control device according to any one of Supplementary Items 1 to 9, wherein:

[0239] When the absolute value of the difference is less than the first threshold or the third threshold and greater than the second threshold, and the positive and negative directions of the difference have been reversed for a predetermined number of frames, the processor sets the threshold to be compared with the absolute value of the difference to the third threshold that is larger than the second threshold, and terminates the exposure control.

[0240] [Supplementary Item 11]

[0241] The exposure control device according to supplementary item 10, wherein:

[0242] The processor performs processing for storing the difference in a storage unit.

[0243] [Supplementary Item 12]

[0244] The exposure control device according to Supplementary Item 11, wherein:

[0245] The processor performs the following processing:

[0246] storing, in the storage unit, for each frame, information on whether the absolute value of the difference is greater than the first threshold, the second threshold, or the third threshold and the exposure control is in progress, or information on whether the absolute value of the difference is less than the first threshold, the second threshold, or the third threshold and the exposure control is ended; and

[0247] The difference is stored in the storage unit only when the first frame is in the exposure control state.

[0248] [Supplementary Item 13]

[0249] An exposure control device according to any one of Supplementary Items 7 to 12, wherein:

[0250] The processor performs the following processing:

[0251] storing, in the storage unit, a history of the absolute value of the difference when the exposure control is terminated; and

[0252] When the maximum value in the history is smaller than the second threshold, the second threshold is subtracted from the maximum value.

[0253] [Supplementary Item 14]

[0254] The exposure control device according to Supplementary Item 13, wherein:

[0255] When a preset number of the histories are stored in the storage unit, the processor performs processing of subtracting the second threshold value from the maximum value.

[0256] [Supplementary Item 15]

[0257] The exposure control device according to Supplementary Item 13 or 14, wherein:

[0258] When receiving a preset operation command, the processor does not inherit the history stored in the storage unit.

[0259] [Supplementary Item 16]

[0260] The exposure control device according to supplementary item 15, wherein:

[0261] The processor deletes the history from the storage unit when receiving a preset operation command.

[0262] [Supplementary Item 17]

[0263] A camera device comprising:

[0264] The exposure control device according to any one of supplementary items 1 to 16; and

[0265] Imaging element.

[0266] The technology of the present invention can also appropriately combine the various embodiments and / or various variations described above. Furthermore, it is not limited to the above embodiments, and various structures can be adopted as long as they do not deviate from the main purpose. In addition, the technology of the present invention also relates to a storage medium that stores the program non-temporarily in addition to the program.

[0267] The recorded contents and illustrated contents shown above are detailed descriptions of the parts involved in the technology of the present invention, which are only an example of the technology of the present invention. For example, the descriptions related to the above-mentioned structure, function, action and effect are descriptions related to an example of the structure, function, action and effect of the parts involved in the technology of the present invention. Therefore, without departing from the scope of the technical purpose of the present invention, it is of course possible to delete unnecessary parts of the recorded contents and illustrated contents shown above, or to add or replace new elements. In addition, in order to avoid complicated situations and facilitate understanding of the parts involved in the technology of the present invention, descriptions related to technical common sense that does not particularly need to be explained in terms of enabling the implementation of the technology of the present invention are omitted in the recorded contents and illustrated contents shown above.

[0268] In this specification, "A and / or B" has the same meaning as "at least one of A and B". That is, "A and / or B" may mean only A, only B, or a combination of A and B. Furthermore, in this specification, the same idea as "A and / or B" applies to the case where three or more items are linked and marked with "and / or".

[0269] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, or technical standard was specifically and individually described as being incorporated by reference.

[0270] Explanation of symbols

[0271] 10-camera device, 11-camera optical system, 12-imaging element, 13-objective lens, 14-focusing lens, 15-zoom lens, 16-aperture, 17-focusing lens driving mechanism, 18-zoom lens driving mechanism, 19-aperture opening adjustment mechanism, 20-control unit, 21-operating unit, 22-camera surface, 23-imaging element driver, 24-shutter, 25-shutter driving mechanism, 30-image input controller, 31-image memory, 32-image processing unit, 33, 53-bus, 34-VRAM, 35-display control unit, 36-media controller, 37-command receiving unit, 38-viewfinder monitor, 39 -Rear monitor, 40-Memory card, 41-Touch panel, 50-Storage device, 51-CPU, 52-Memory, 60-Working program, 61-Status information, 65-Light measuring unit, 66-Calculation unit, 67-Setting unit, 68-Read / write control unit (RW control unit), 69-Judgment unit, 70-Drive control unit, 75-Image data, 76-Light measuring value, 77-Setting information, 78-Judgment information, 85-Counting unit, 86-Update command signal, 90-History information, 95-Power off signal, 96-History clear signal, 100-Subject detection unit, 101-Detection result, 102-Condition, ΔEV-1st item The difference between the first target exposure value and the second target exposure value, ΔEVX-the difference between the first target exposure value and the second target exposure value in the previous frame, |ΔEV|-the absolute value of the difference, |ΔEV|max-the maximum absolute value of the difference, EV1-the first target exposure value, EV2-the second target exposure value, NR-the number of inversions, OA-optical axis, SF-the number of set frames, SN-the number of settings, ST100, ST105, ST110, ST115, ST120, ST125, ST130, ST135, ST140, ST145, ST150, ST155, ST160, ST165, ST170, ST17 5. ST180, ST185, ST190, ST195, ST200, ST205, ST210, ST215, ST300, ST305, ST310, ST315, ST320, ST325, ST330, ST335, ST340, ST345, ST350, ST355, ST400, ST405, ST410, ST415, ST420, ST425, ST430 - steps, TH1 - the first threshold, TH2 - the second threshold, TH2max - the second threshold, TH3_1 - the 3_1st threshold, TH3_2 - the 3_2nd threshold.

Claims

1. An exposure control device for performing exposure control so that an exposure value in an imaging device follows a target exposure value, The exposure control device includes a processor, and the processor performs the following processing: starting the exposure control when an absolute value of a difference between a first target exposure value of a first frame captured by the imaging device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold; acquiring a second threshold value smaller than the first threshold value in response to the start of the exposure control; and When the magnitude relationship between the absolute value of the difference and the second threshold satisfies a preset condition, the threshold to be compared with the absolute value of the difference is set to a third threshold greater than the second threshold, and the exposure control is terminated.

2. The exposure control device according to claim 1, wherein: The processor sets the third threshold to the same value as the first threshold.

3. The exposure control device according to claim 1, wherein: The processor sets the third threshold to a value different from the first threshold according to a condition.

4. The exposure control device according to claim 3, wherein: The processor sets the third threshold to a value smaller than the first threshold based on the condition.

5. The exposure control device according to claim 3, wherein: The condition is a condition based on the detection result of the object.

6. The exposure control device according to claim 1, wherein: When the absolute value of the difference becomes equal to or smaller than the second threshold, the processor sets a threshold to be compared with the absolute value of the difference to the third threshold that is larger than the second threshold, and terminates the exposure control.

7. The exposure control device according to claim 1, wherein: The processor performs the following processing: Whether the absolute value of the difference is greater than the first threshold, the second threshold or the third threshold and is in an exposure control state in which the exposure control is being performed, or whether the absolute value of the difference is less than the first threshold, the second threshold or the third threshold and is in an exposure control end state in which the exposure control has been ended, is stored in the storage unit for each frame.

8. The exposure control device according to claim 7, wherein: The processor performs the following processing: When the second frame is in the exposure control end state, setting the threshold to be compared with the absolute value of the difference to the first threshold or the third threshold; and When the second frame is in the exposure control state, a threshold to be compared with the absolute value of the difference is set as the second threshold.

9. The exposure control device according to claim 7, wherein: The processor performs a process of storing the second target exposure value in the storage unit for each frame.

10. The exposure control device according to claim 1, wherein: When the absolute value of the difference is less than the first threshold or the third threshold and greater than the second threshold, and the positive and negative reversal state of the difference continues for a predetermined number of frames, the processor sets the threshold for comparison with the absolute value of the difference to the third threshold that is larger than the second threshold, and terminates the exposure control.

11. The exposure control device according to claim 10, wherein: The processor performs processing for storing the difference in a storage unit.

12. The exposure control device according to claim 11, wherein: The processor performs the following processing: storing in the storage unit for each frame whether the absolute value of the difference is greater than the first threshold, the second threshold, or the third threshold and the exposure control is in progress, or whether the absolute value of the difference is less than the first threshold, the second threshold, or the third threshold and the exposure control is ended; and The difference is stored in the storage unit only when the first frame is in the exposure control state.

13. The exposure control device according to claim 7, wherein: The processor performs the following processing: storing, in the storage unit, a history of the absolute value of the difference when the exposure control is terminated; and When the maximum value in the history is smaller than the second threshold, the second threshold is subtracted from the maximum value.

14. The exposure control device according to claim 13, wherein: When a preset number of the histories are stored in the storage unit, the processor performs processing of subtracting the second threshold value from the maximum value.

15. The exposure control device according to claim 13, wherein: When receiving a preset operation command, the processor does not inherit the history stored in the storage unit.

16. The exposure control device according to claim 15, wherein: The processor deletes the history from the storage unit when receiving a preset operation command.

17. A camera device comprising: The exposure control device according to any one of claims 1 to 16; and Imaging element.

18. An operating method of an exposure control device, the exposure control device performing exposure control so that an exposure value in an imaging device follows a target exposure value, The working method of the exposure control device comprises the following steps: starting the exposure control when an absolute value of a difference between a first target exposure value of a first frame captured by the imaging device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold; acquiring a second threshold value smaller than the first threshold value in response to the start of the exposure control; and When the magnitude relationship between the absolute value of the difference and the second threshold satisfies a preset condition, the threshold to be compared with the absolute value of the difference is set to a third threshold greater than the second threshold, and the exposure control is terminated.

19. A computer-readable storage medium storing a working program of an exposure control device, wherein the exposure control device performs exposure control so that an exposure value in an imaging device follows a target exposure value, The operating program of the exposure control device causes the computer to execute a process including the following steps: starting the exposure control when an absolute value of a difference between a first target exposure value of a first frame captured by the imaging device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold; acquiring a second threshold value smaller than the first threshold value in response to the start of the exposure control; and When the magnitude relationship between the absolute value of the difference and the second threshold satisfies a preset condition, the threshold to be compared with the absolute value of the difference is set to a third threshold greater than the second threshold, and the exposure control is terminated.

20. A computer program product comprising an operating program of an exposure control device, the exposure control device performing exposure control so that an exposure value in an imaging device follows a target exposure value, The operating program of the exposure control device causes the computer to execute a process including the following steps: starting the exposure control when an absolute value of a difference between a first target exposure value of a first frame captured by the imaging device and a second target exposure value of a second frame captured earlier than the first frame is greater than a first threshold; acquiring a second threshold value smaller than the first threshold value in response to the start of the exposure control; and When the magnitude relationship between the absolute value of the difference and the second threshold satisfies a preset condition, the threshold to be compared with the absolute value of the difference is set to a third threshold greater than the second threshold, and the exposure control is terminated.

Images