Imaging device

Abstract

To perform continuous imaging with high exposure accuracy.SOLUTION: An imaging apparatus 100 includes an image sensor 103 that accumulates charge according to the amount of light received, a first light shielding member L that travels from a light shielding position to a retracted position with respect to the image sensor, a second light shielding member T that travels from the retracted position relative to the image sensor to the light shielding position, and control means 102 that controls the travel of the first light shielding member, the electronic front curtain operation of the image sensor, and the travel of the second light shielding member. The control means starts the movement of the first light shielding member in each image capturing during continuous image capturing, and then starts the electronic front curtain operation and the charge accumulation of the image sensor, and also starts the second light shielding member. When the second light shielding member is caused to travel according to the set exposure time, the first light shielding member is started to travel so as to be completed after the start of the electronic front curtain operation.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an imaging device that combines a mechanical shutter and an electronic shutter.

Background Art

[0002] Some imaging devices control the exposure time by using both an electronic front curtain that controls the start timing of charge accumulation for each line during the exposure of an image sensor and a mechanical rear curtain that ends the exposure. Patent Document 1 discloses an imaging device that uses an electronic front curtain instead of a mechanical front curtain so that vibrations (shocks) generated at the completion of the travel of the mechanical front curtain do not affect imaging.

[0003] In addition, some imaging devices having an electronic front curtain and a mechanical rear curtain have a mechanical front curtain as a light-shielding curtain that is not used for exposure control but quickly performs the charge operation of the mechanical rear curtain for the next imaging while reading out signals from the image sensor. In this imaging device, the charge operations of the mechanical front curtain and the mechanical rear curtain are performed during signal readout after imaging using the electronic front curtain, and after the completion of the charge operation, the mechanical front curtain is run to retract it from the optical path to the image sensor, and charge accumulation by the electronic front curtain for the next imaging is started in this state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when performing high-speed continuous still image capture (hereinafter also simply referred to as continuous imaging) in an imaging device that moves the mechanical front curtain before the start of charge accumulation by the electronic front curtain, as described above, the following problems arise. If the charging operation of the mechanical front curtain is slower than the signal readout from the image sensor during continuous imaging, charge accumulation by the electronic front curtain for the next image will begin immediately after the mechanical front curtain has moved. In this case, when the mechanical rear curtain starts moving after the start of charge accumulation by the electronic front curtain, a shock may occur due to the completion of the mechanical front curtain's movement, affecting the movement of the mechanical rear curtain and potentially reducing exposure accuracy.

[0006] The present invention provides an imaging device that can improve exposure accuracy when exposure control is performed using the electronic front curtain and the mechanical rear curtain after the mechanical front curtain starts moving during continuous imaging. [Means for solving the problem]

[0007] An imaging device as one aspect of the present invention includes an image sensor that accumulates charge according to the amount of light received, a first light-shielding member that moves from a position that shields the image sensor to a position that retracts, a second light-shielding member that moves from the retracted position to a position that shields the image sensor, and control means that control the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member. The control means, in each image taken during continuous imaging, starts the movement of the first light-shielding member, then starts the electronic front curtain operation and charge accumulation of the image sensor, and when moving the second light-shielding member according to a set exposure time, starts the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation. The control means selects whether to perform a first control or a second control to start the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation, depending on the conditions for continuous imaging, the conditions for continuous imaging being the continuous imaging speed or the imaging interval, and the control means performs the first control when the continuous imaging speed is a first speed or the imaging interval is a first interval, and performs the second control when the continuous imaging speed is a second speed that is slower than the first speed or the imaging interval is a second interval that is longer than the first interval. It is characterized by the following:

[0009] Furthermore, another aspect of the present invention is a control method applied to an imaging device having an image sensor that accumulates charge according to the amount of light received, a first light-shielding member that moves from a position that shields the image sensor to a position that retracts, and a second light-shielding member that moves from a position that retracts from the image sensor to a position that shields the image sensor. This method controls the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member. This control method includes, in each image taken during continuous imaging, the steps of starting the movement of the first light-shielding member, starting the electronic front curtain operation and charge accumulation of the image sensor, and moving the second light-shielding member according to a set exposure time, wherein the movement of the first light-shielding member is started so as to be completed after the start of the electronic front curtain operation. The system selects, depending on the conditions for continuous imaging, to perform either a first control to cause the first light-shielding member to move, or a second control to start the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The conditions for continuous imaging are the continuous imaging speed or the imaging interval. If the continuous imaging speed is a first speed or the imaging interval is a first interval, the system performs the first control. If the continuous imaging speed is a second speed that is slower than the first speed or the imaging interval is a second interval that is longer than the first interval, the system performs the second control. It is characterized by the following:

[0010] Na Furthermore, a program that causes the computer of the imaging device to execute processes according to each of the above control methods also constitutes another aspect of the present invention. [Effects of the Invention]

[0011] According to the present invention, exposure accuracy can be improved when exposure control is performed using an electronic front curtain and a second light-shielding member after the first light-shielding member starts moving during continuous imaging. [Brief explanation of the drawing]

[0012] [Figure 1] A block diagram showing the configuration of an imaging system including the imaging device of the embodiment. [Figure 2] A diagram showing the operating timing in continuous imaging control in conventional and embodiment imaging devices. [Figure 3] A diagram showing the travel timing of the mechanical front curtain, electronic front curtain, and mechanical rear curtain in the embodiment. [Figure 4] A diagram showing the operating timing for other continuous imaging controls in the imaging device of the embodiment. [Figure 5] A flowchart illustrating the continuous imaging process in the embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Examples]

[0014] Figure 1 shows the configuration of an imaging system consisting of a digital camera (hereinafter simply referred to as "camera") 100 as an imaging device and an interchangeable lens unit 150 detachably attached thereto, which is Embodiment 1 of the present invention. The shutter 101 is a focal-plane shutter that controls the exposure time of the imaging unit 103 (hereinafter referred to as "exposure control") in accordance with the control by the system control unit 102, which is a control means. The shutter 101 has a mechanical front curtain (first light-shielding member: hereinafter referred to as "mechanical front curtain") and a mechanical rear curtain (second light-shielding member: hereinafter referred to as "mechanical rear curtain"), both of which move a plurality of light-shielding blades. The mechanical front curtain moves from a light-shielding position that blocks light from the interchangeable lens unit 150 to a retracted position relative to the image sensor of the imaging unit 103. The mechanical rear curtain moves from the retracted position to a light-shielding position relative to the image sensor 103. In this embodiment, as will be described later, the mechanical front curtain is used as a light-shielding curtain but is not used for exposure control, and only the mechanical rear curtain is used for exposure control. However, a mechanical front curtain may be used for exposure control.

[0015] Before travel, the mechanical front curtain and mechanical rear curtain are charged and held in a position biased in the direction of travel by a charge spring, which is a biasing member not shown. In this charge drive, the mechanical front curtain and mechanical rear curtain may be driven by a single motor, or they may be driven by separate motors.

[0016] The imaging unit 103 is composed of an imaging device such as a CCD sensor or a CMOS sensor that converts an optical image (subject image) formed by the imaging lens 151 in the interchangeable lens unit 150 into an electrical signal. The imaging device accumulates charges corresponding to the amount of received light at each of a plurality of pixels provided on its imaging surface. At this time, the imaging device can perform a reset operation for starting charge accumulation for each pixel line (region: hereinafter simply referred to as a line) on the imaging surface, that is, an electronic shutter operation for scanning the reset lines. In the following description, the electronic shutter operation is simply referred to as an electronic shutter. The A / D converter 104 converts the analog signal from the imaging unit 103 into a digital signal (imaging data).

[0017] The image processing unit 105 performs image processing such as pixel interpolation processing, resizing processing, and color conversion processing on the imaging data from the A / D converter 104 or the imaging data from the memory control unit 106 to generate image data. Further, the image processing unit 105 performs predetermined arithmetic processing using the image data. The system control unit 102 performs AE (automatic exposure) processing, AF (auto focus) processing, AWB (auto white balance) processing, etc. using the arithmetic result in the image processing unit 105.

[0018] The imaging data from the A / D converter 104 is written into the memory 107 via the image processing unit 105 and the memory control unit 106 or via only the memory control unit 106. The memory 107 stores imaging data and image data for display on the display unit 109.

[0019] The D / A converter 108 converts the display image data stored in the memory 107 into an analog signal and supplies it to the display unit 109. Thereby, a display image (such as a live view image) corresponding to the display image data written in the memory 107 is displayed on the display unit 109 composed of a display device such as an LCD.

[0020] The non-volatile memory 110 is a recording medium that can be electrically recorded and erased, such as an EEPROM. The non-volatile memory 110 stores constants, programs, etc. for the operation of the system control unit 102.

[0021] The system control unit 102 includes at least one processor and controls the operation of the entire camera 100 by executing a program recorded in the non-volatile memory 110. The system memory 111 is composed of RAM, stores constants and variables for the operation of the system control unit 102, and also expands programs and the like read from the non-volatile memory 110. The system timer 112 counts the time used for various controls and the time of the built-in clock.

[0022] The mode switch 113, the shutter button 114, and the operation unit 115 are operated for the user to input various operation instructions to the system control unit 102. The mode switch 113 is operated to switch the camera mode to any one of the still image shooting mode, the video shooting mode, and the playback mode. The first shutter switch 116 turns on when the shutter button 114 is half-pressed and generates a first shutter signal SW1. The system control unit 102 starts AE processing, AF processing, AWB processing, etc. in response to the first shutter signal SW1.

[0023] The second shutter switch 117 turns on when the shutter button 114 is fully pressed and generates a second shutter signal SW2. The system control unit 102 starts a series of imaging processes from the signal reading from the imaging unit 103 to the writing of image data to the recording medium 160 in response to the second shutter signal SW2.

[0024] The operation unit 115 includes various operation members related to the operation of the camera 100 and the interchangeable lens unit 150. When a touch sensor is provided on the display screen of the display unit 109, the touch sensor is also included in the operation unit 115.

[0025] The power switch 123 is operated to switch the power of the camera 100 ON / OFF. The power control unit 118 consists of a battery detection circuit, a DC-DC converter, and a switch circuit for switching the power supply block, and detects whether a battery is installed in the camera 100, the type of battery installed, and the remaining battery level. The power control unit 118 also controls a DC-DC converter (not shown) based on the detection results and instructions from the system control unit 102, and supplies the necessary voltage to each part, including the recording medium 160, for the required period of time.

[0026] The power supply unit 119 consists of a primary battery, a secondary battery, and an AC adapter, etc. The recording medium I / F 120 is an interface with a recording medium 160 such as a memory card or a hard disk. The recording medium 160 records image data for recording purposes that is generated by imaging.

[0027] The communication unit 121 transmits and receives image data, audio data, etc., to and from external devices wirelessly or via wired connection. The attitude detection unit 122 is composed of an acceleration sensor, a gyroscope, etc., and detects the attitude of the camera 100 relative to the direction of gravity. The system control unit 102 rotates the image data or adds attitude information to the image data file according to the attitude detected by the attitude detection unit 122.

[0028] The interchangeable lens unit 150 has an imaging lens 151 and an aperture 154. Although the imaging lens 151 is composed of multiple lenses, it is shown as a single lens in the figure. The lens communication terminal 161 and the camera communication terminal 162 are connected to each other, enabling communication between the lens system control circuit 152 and the system control unit 102. The system control unit 102 controls the AF drive circuit 155 and the aperture drive circuit 153 via the lens system control circuit 152 through communication via these communication terminals 161 and 162. When the AF drive circuit 155 is controlled, the focus lens in the imaging lens 151 is driven and autofocus is performed. Also, when the aperture drive circuit 153 is controlled, the aperture diameter (aperture value) of the aperture 154 is changed.

[0029] Figures 2(a) and (b) illustrate the operation of continuous still image capture (hereinafter simply referred to as continuous imaging), which involves continuously capturing still images using the electronic front curtain of the image sensor (hereinafter referred to as electronic front curtain imaging). In electronic front curtain imaging, the mechanical front curtain is not used for exposure control. Instead, the exposure time is controlled by scanning the electronic front curtain and moving the mechanical rear curtain, which control the timing of the start of charge accumulation for each line of the image sensor (i.e., the charge reset operation). The mechanical front curtain is initially in the retracted position during the first image capture, and moves from the light-shielding position to the retracted position with each subsequent image capture (i.e., in each image capture during continuous imaging). In each figure, the horizontal axis represents time. From top to bottom, the figures show: 1. Charge accumulation and readout of the image sensor, 2. Movement of the mechanical front curtain, 3. Movement of the mechanical rear curtain, and 4. Charging operation of the mechanical front and rear curtains (mechanical charge) and release, which will be described later. The bottom row shows the positions of the mechanical front curtain (L) and mechanical rear curtain (T) relative to the image sensor, with the shaded area indicating the imaging surface of the image sensor within the shutter opening.

[0030] Figure 2(a) shows a conventional continuous imaging control. At time tx0, before the start of charge accumulation for the first image of continuous imaging, the mechanical front curtain is retracted from the shutter opening (imaging plane) because it is not used for exposure control.

[0031] At time tx1, scanning of the electronic front curtain and charge accumulation of the image sensor begin. The image sensor begins accumulating charge before the mechanical rear curtain, which has started moving according to the set shutter speed, comes into contact with the shutter opening.

[0032] At time tx2, the power supply to the magnet coil that was holding the mechanical rear curtain in a charged state is cut off, causing the mechanical rear curtain to move.

[0033] At time tx3, the exposure of the image sensor ends when the mechanical rear curtain completes its movement. The image sensor then begins reading out the accumulated charge (signal).

[0034] At time tx4, the charging operation of the mechanical front curtain and mechanical rear curtain is started after waiting for the vibration generated by the completion of the mechanical rear curtain's movement (hereinafter referred to as rear curtain shock) to subside. During signal readout from the image sensor from time tx4 to the next time tx5, the charging operation of the mechanical front curtain and mechanical rear curtain is performed via a motor-driven cam and a charging lever driven by the cam, while the image sensor is shielded by the mechanical front curtain in order to take the next image.

[0035] At time tx5, the signal readout from the image sensor is completed.

[0036] At time tx6, the mechanical rear curtain moves to its retracted position before image capture begins due to a charging operation, and the mechanical front curtain moves to a light-shielding position that blocks the shutter opening due to a charging operation. When the charging operation in which the cam charges the charging lever is completed, the mechanical front curtain and mechanical rear curtain, which are driven together with the charging lever, are attracted and held by the magnetic surface of the energized magnetic coil, and the cam is driven to retract from the movement trajectory of the charging lever, thus releasing the set.

[0037] Afterward, the system waits for the vibrations caused by the release of the set to subside, and then the next electronic front curtain image is taken again. That is, the power to the magnetic coil for the mechanical front curtain is released, and the mechanical front curtain is moved to retract from the shutter opening. In some cases, the completion of the signal readout from the image sensor at time tx5 may be later than the completion of the charge operation; in such cases, the system waits for the signal readout to be completed before moving the mechanical front curtain.

[0038] At time TX7, the mechanical front curtain movement is completed.

[0039] At time tx8, after the imaging interval from time tx5, scanning of the electron front curtain and charge accumulation are started again, just as at time tx1.

[0040] At time tx9, the mechanical rear curtain starts moving after the exposure time TX0 has elapsed from the accumulation start time tx8. The exposure time TX0 varies depending on AE processing and user settings.

[0041] In this conventional control system, at time tx9, a front curtain shock occurs as a vibration caused by the completion of the mechanical front curtain's movement, at the time TX1 elapsed from the completion of the mechanical front curtain's movement at time tx7 (vibration occurrence time). The time at which the front curtain shock occurs varies depending on the charging operation corresponding to the state of the shutter 101, which changes the timing of the mechanical front curtain's movement start. Specifically, depending on the time required for the charging operation described later, the timing of the mechanical front curtain's movement start may be before or after the rear curtain's movement start. As a result, as shown in the figure, the timing of the front curtain shock may coincide with the timing of the mechanical rear curtain's movement start (time tx9). In this case, the front curtain shock affects the movement of the mechanical rear curtain, reducing exposure accuracy. In particular, if the timing of the front curtain shock and the timing of the mechanical rear curtain's movement coincide in high-speed imaging where the exposure time is shorter than, for example, 1 / 1000 of a second (first time), the effect of the mechanical rear curtain's movement on the image becomes greater due to the short exposure time.

[0042] To prevent problems caused by front curtain shock, it is possible to modify the configuration of the shutter 101 to expedite the completion of the charging operation at time tx6, but this would complicate the configuration. Furthermore, if the system is controlled to wait for the front curtain shock to subside after the mechanical front curtain has finished moving at time tx8 before starting exposure control, the continuous imaging speed will decrease.

[0043] In this embodiment, the impact of front curtain shock on exposure accuracy is reduced while improving the continuous imaging speed. Figure 2(b) shows the continuous imaging control in this embodiment. The times tx0' to tx5' are the same as the times tx0 to tx5 in Figure 2(a). Also, the time from tx5' to tx8' is the same imaging interval (first interval) as the times tx5 to tx8 in Figure 2(a).

[0044] At time tx6', the charge operation is terminated and the set is released, similar to Figure 2(a). However, in this embodiment, the mechanical front curtain is not started to move at this point, and is started to move at time tx7'. Time tx7' is a predetermined time, which is the mechanical front curtain control time TX2', before the next accumulation start time tx8'. Note that the accumulation start time tx8', which is the starting point for setting the mechanical front curtain control time TX2', may be the actual start time of charge accumulation of the image sensor, or it may be the start time of scanning of the electronic front curtain, which is slightly earlier.

[0045] The mechanical front curtain control time TX2' is set to a time that ensures the mechanical front curtain completes its movement before charge accumulation begins on all lines of the image sensor (in other words, before the scanning of the electronic front curtain is completed) (details are explained using Figure 3). If the mechanical front curtain control time TX2' is too small, the mechanical front curtain will catch up to the electronic front curtain, making proper exposure control impossible. By setting the start timing of the mechanical front curtain movement to time tx7', a front curtain shock occurs at time tx11', after the front curtain shock occurrence time TX1' (=TX1) has elapsed from the mechanical front curtain movement completion time tx10'.

[0046] Furthermore, if the time of the front curtain shock occurrence tx11' (= accumulation start time tx8' - mechanical front curtain control time TX2' + mechanical front curtain travel time + front curtain shock occurrence time TX1') is later than the time of the start of mechanical rear curtain travel tx9' (= accumulation start time tx8' + exposure time TX0'), then the front curtain shock will not affect the start of mechanical rear curtain travel. In other words, exposure accuracy will not decrease. Thus, the control that completes the movement of the mechanical front curtain after the start of scanning of the electronic front curtain but before the completion of scanning of the electronic front curtain, or more precisely, before the start of mechanical rear curtain travel (the first control), will be referred to as the first mechanical front curtain travel control in the following explanation.

[0047] Furthermore, if the exposure time TX0' is longer than the first time described above, the mechanical rear curtain movement start time tx9' and the front curtain shock occurrence time tx11' may coincide. However, in this case, because the exposure time is long, the front curtain shock has little effect on exposure accuracy. Therefore, if the exposure time TX0' is longer than the first time, it is sufficient to control the system so that the mechanical front curtain movement is completed before the electronic front curtain starts, as in the conventional method.

[0048] Figure 3 shows the time variation of the movement positions of the mechanical front curtain and mechanical rear curtain (movement characteristics of the mechanical front curtain and mechanical rear curtain) and the time variation of the scanning position of the electronic front curtain (operation characteristics of the electronic front curtain operation) in continuous imaging control including the first mechanical front curtain movement control. The horizontal axis represents time, and the vertical axis represents the start and end positions of the movement of the mechanical front curtain and mechanical rear curtain, as well as the vertical position of the imaging surface (imaging area) of the image sensor. The mechanical front curtain and mechanical rear curtain move from a mechanical movement start position below the lower edge of the imaging surface to a mechanical movement completion position above the upper edge of the imaging surface.

[0049] The mechanical front curtain travel position 301 indicates the time change in the position of the lower end of the mechanical front curtain, and the mechanical rear curtain travel position 303 indicates the time change in the position of the upper end of the mechanical rear curtain. The electronic front curtain scanning position 302 indicates the time change in the scanning position of the electronic front curtain. As can be seen from the electronic front curtain scanning position 302 and the mechanical rear curtain travel position 303, the image sensor begins accumulating charge before the mechanical rear curtain enters the shutter opening. The timing of the start of this charge accumulation is controlled for each line (region) of the image sensor so that the exposure amount is uniform across the entire imaging surface, in accordance with the travel characteristics of the mechanical rear curtain as it travels while accelerating.

[0050] Time ty0 corresponds to the start timing of the mechanical front curtain movement, which is time tx7' in Figure 2(b). As can be seen from the mechanical front curtain movement position 301 and the electronic front curtain scanning position 302, the movement of the mechanical front curtain is completed after the start of the electronic front curtain scanning but before the electronic front curtain scanning is completed.

[0051] The mechanical front curtain travel characteristics shown at mechanical front curtain travel position 301 vary depending on individual shutter differences and the number of cycles the shutter can withstand. Furthermore, the scanning characteristics (operating characteristics) of the electronic front curtain shown at electronic front curtain scanning position 302 are set to match the mechanical rear curtain travel characteristics shown at mechanical rear curtain travel position 303. From the perspective of the impact of shutter shock on exposure control, it is preferable to delay the timing of the front curtain shock. Therefore, it is preferable that the mechanical front curtain control time TX2' in Figure 2(b) be as short as possible, meaning that time tx7' should be as late as possible (as close as possible to the accumulation start time tx8'). However, due to the difference between the mechanical front curtain travel characteristics and the electronic front curtain scanning characteristics, there is a risk that the mechanical front curtain travel position 301 may catch up to the electronic front curtain scanning position 302; therefore, a time that takes this into account is set as the mechanical front curtain control time TX2'.

[0052] Furthermore, the electronic front curtain scanning position 302' indicates the changed scanning characteristics when control is performed to alter the scanning characteristics of the electronic front curtain. When such control of scanning characteristics is performed, the mechanical front curtain control time TX2' needs to be made longer so that the mechanical front curtain travel position 301 does not catch up to the electronic front curtain scanning position 302. Thus, the mechanical front curtain control time TX2' may be changed in accordance with the change in the scanning characteristics of the electronic front curtain, or it may be set to a constant value that takes all of these into account. When the scanning characteristics of the electronic front curtain are changed according to the exposure time, the length of the mechanical front curtain control time TX2' may be changed according to the exposure time.

[0053] Using Figures 4(a) and 4(b), we will explain a continuous imaging control that differs from the first continuous imaging control including the mechanical front curtain travel control shown in Figure 2(b). Figure 4(a) shows the operation timing when a live view image is displayed between images in continuous imaging. In this case, the continuous imaging speed becomes a second speed, which is slower than the first speed in Figure 2(b), and the imaging interval becomes a second interval, which is longer than the first interval in Figure 2(b).

[0054] At time tz1, when the mechanical front curtain has finished moving, the accumulation of display charge (hereinafter referred to as LV accumulation) for generating a live view image is started. In this case, the front curtain shock occurs at the front curtain shock occurrence time tz2, which is after the front curtain shock occurrence time TZ1 has elapsed from time tz1, during LV accumulation. Therefore, the time TZ2 from the front curtain shock occurrence time tz2 to the start time of charge accumulation for the next image at tz3 is longer than 0 seconds. Consequently, the first mechanical front curtain movement control, which moves the mechanical front curtain by the mechanical front curtain control time TX2' from the accumulation start time tx8' (=tz3) as explained in Figure 2(b), is unnecessary. In other words, when displaying a live view image between images in continuous imaging, the first mechanical front curtain movement control should not be executed, and the control that completes the movement of the mechanical front curtain before the start of scanning of the electronic front curtain (second control: hereinafter referred to as the second mechanical front curtain movement control) should be selected.

[0055] Furthermore, if the camera 100 has an imaging mode that detects flicker of the light source illuminating the subject, the execution or non-execution of the first mechanical front curtain travel control may be selected depending on whether or not to perform charge accumulation to detect the presence or absence of flicker.

[0056] Figure 4(b) shows the operating timing when the time required for mechanical charging (and release) is short. The time required for mechanical charging varies depending on the durability status of the shutter 101, power supply voltage, ambient temperature, and individual differences. In the case of Figure 4(b), the continuous imaging speed (imaging interval) is the same as in Figure 2(b), but the time required for mechanical charging is shorter than in Figure 2(b).

[0057] If signal readout from the image sensor is already complete and mechanical charging is complete at time tz1', the mechanical front curtain movement is started at time tz1'. In this case, a front curtain shock occurs at time tz2' after the mechanical front curtain movement is complete. Since the time TZ2' from the time of the front curtain shock tz2' to the start time of the next image accumulation tz3' is longer than 0 seconds, the first mechanical front curtain movement control is unnecessary. Therefore, it is sufficient to select the execution of the second mechanical front curtain movement control, which completes the movement of the mechanical front curtain before the start of scanning of the electronic front curtain.

[0058] Furthermore, if the first mechanical front curtain timing control is performed, imaging with acceptable exposure accuracy is possible even if there is front curtain shock when the exposure time is short. However, when the exposure time is long, front curtain shock does affect exposure accuracy to some extent, so it is desirable that front curtain shock not occur during exposure. In addition, front curtain shock during exposure may also affect the performance of the vibration isolation control in the interchangeable lens unit 150, in which the lens system control circuit 152 displaces the vibration isolation lens relative to the optical axis. For this reason, it is desirable that front curtain shock not occur during exposure. For this reason, the execution / non-execution of the first mechanical front curtain travel control may be switched depending on whether or not a time TZ2' longer than 0 seconds can be secured.

[0059] Thus, in this embodiment, one of the first or second mechanical front curtain travel control methods is selected depending on the continuous imaging conditions, such as the exposure time, continuous imaging speed, imaging interval, whether or not to display a live view image (accumulation of display charge) between imaging, and whether the front curtain shock occurs before or after the start of scanning of the electronic front curtain. In other words, the timing of the start of mechanical front curtain travel relative to the start of scanning of the electronic front curtain is made different depending on the continuous imaging conditions.

[0060] The flowchart in Figure 5 illustrates the continuous imaging process in this embodiment. The system control unit 102, acting as a computer, executes this process by loading the program stored in the non-volatile memory 110 into the system memory 111 and executing it. In the following description, S represents a step. Here, the process begins with the mechanical front curtain of the shutter 101 retracted from the shutter opening.

[0061] In S501, the system control unit 102 determines whether or not a second shutter signal SW2 has been input from the second shutter switch 117 in response to the full press operation of the shutter button 114. If the second shutter signal SW2 is not input, this determination is repeated; if it is input, the process proceeds to S502.

[0062] In S502, the system control unit 102 uses the system timer 112 to wait for time to elapse until the scheduled imaging time. This is intended to stabilize the time between the user fully pressing the shutter button 114 and the start of imaging, thereby enabling the user to start accumulating charge in the imaging unit (image sensor) 103 at the timing intended by the user.

[0063] In S503, the system control unit 102 initiates charge accumulation on the image sensor. That is, it initiates charge accumulation that runs the electronic front curtain, which resets the image sensor line by line.

[0064] In S504, the system control unit 102 waits for a predetermined exposure time to elapse using the system timer 112.

[0065] In S505, the system control unit 102 moves the mechanical rear curtain of the shutter 101. Once the movement of the mechanical rear curtain is complete, in S506, the system control unit 102 starts reading out the charge (signal) accumulated in the image sensor.

[0066] In S507, the system control unit 102 uses the system timer 112 to wait for the rear curtain shock to subside after the mechanical rear curtain has finished moving before performing the charging operation and releasing the mechanical front curtain and mechanical rear curtain.

[0067] In S508, the system control unit 102 determines whether to continue imaging (perform the next image). This determination is based on whether continuous imaging is set as the imaging setting (single image), whether the second shutter signal SW2 is still input, whether there is remaining storage capacity in the recording medium 160, etc. If imaging is not to be continued, the process proceeds to S509 to perform the imaging termination process and end this process. In the imaging termination process, the shutter 101 is returned to the imaging standby state, and the imaging lens 151 is returned to the imaging standby state via the lens system control circuit 152 and aperture drive circuit 153. If imaging is to be continued (i.e., continuous imaging begins), the process proceeds to S510.

[0068] In S510, the system control unit 102 determines whether the continuous imaging mode is one in which the display of a live view image is interspersed between imaging, as shown in Figure 4(a). If it is a mode in which the display of a live view image is interspersed, the process proceeds to S511; otherwise, it proceeds to S520.

[0069] In S511, the system control unit 102 moves the mechanical front curtain at the conventional timing to retract the mechanical front curtain from the shutter opening.

[0070] In S512, the system control unit 102 causes the image sensor to accumulate charge in order to generate a live view image.

[0071] In S513, the system control unit 102 reads the signal for generating the live view image that has been stored from the image sensor. Then, it returns to S502 and waits again until the next scheduled imaging time.

[0072] In S520, the system control unit 102 calculates whether a front curtain shock will occur during exposure. If it does not occur, the process proceeds to S521; if it does occur, the process proceeds to S530. The determination of whether a front curtain shock will occur during exposure is made by checking if the time calculated as (scheduled start time of accumulation) - (scheduled time of front curtain shock) is longer than 0 seconds. The scheduled time of front curtain shock here is calculated as (current time) + (travel time of the mechanical front curtain) + (time of front curtain shock occurrence (TX1 in Figure 2(a))).

[0073] In S521, the system control unit 102 moves the mechanical front curtain as before at the current time (the end of the charging operation and set release in S507). Then, it returns to S502 and waits again until the next scheduled imaging time.

[0074] In S530, the system control unit 102 waits until a predetermined time (mechanical front curtain control time TX2' in Figure 2(b)) before the scheduled imaging time (accumulation start time tx8' in Figure 2(b)).

[0075] In S531, the system control unit 102 moves the mechanical front curtain. Then, it returns to S502 and waits again until the next scheduled imaging time. By moving the mechanical front curtain at this timing to control the timing of the front curtain shock, it is possible to improve the continuous imaging speed while reducing the impact of the front curtain shock on the movement of the mechanical rear curtain, and thus on exposure accuracy.

[0076] In the above embodiment, continuous imaging processing was described using an interchangeable-lens digital camera, but similar continuous imaging processing can be performed using other imaging devices that have a mechanical shutter and are capable of continuous imaging. (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0077] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of symbols]

[0078] 100 Digital Cameras 101 Shutter 102 System Control Unit 103 Imaging Unit

Claims

1. An image sensor that accumulates charge according to the amount of light received, A first light-shielding member that moves from a position that shields the image sensor to a position that retracts from it, A second light-shielding member that travels from a retracted position relative to the image sensor to a position that shields it from light, The system includes control means for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member. The control means, in each image taken during continuous imaging, after starting the movement of the first light-shielding member, starts the electronic front curtain operation and charge accumulation of the image sensor, and moves the second light-shielding member according to the set exposure time, selects, according to the conditions of continuous imaging, to perform a first control that starts the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control that starts the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The conditions for continuous imaging are the continuous imaging speed or the imaging interval. The imaging apparatus is characterized in that the control means performs the first control when the continuous imaging speed is a first speed or the imaging interval is a first interval, and performs the second control when the continuous imaging speed is a second speed slower than the first speed or the imaging interval is a second interval longer than the first interval.

2. The imaging apparatus according to claim 1, characterized in that, in the first control, the control means causes the movement of the first light-shielding member to be started so as to be completed before the completion of the electronic front curtain operation.

3. The imaging apparatus according to claim 1 or 2, wherein in the first control, the control means causes the movement of the first light-shielding member to be started after the movement of the second light-shielding member has started.

4. In the first control, the control means causes the movement of the first light-shielding member to start a predetermined time before the start of the electronic front curtain operation or the start of charge accumulation of the image sensor. The imaging apparatus according to claim 1, characterized in that the predetermined time in the first control is set to the time at which the movement of the first light-shielding member is completed after the start of the electronic front curtain operation.

5. The imaging apparatus according to claim 4, characterized in that the predetermined time in the first control is set to a time such that the movement of the first light-shielding member is completed before the completion of the electronic front curtain operation.

6. The imaging apparatus according to claim 4 or 5, characterized in that the predetermined time in the first control is set to the time at which the movement of the first light-shielding member is completed after the start of the movement of the second light-shielding member.

7. The imaging device according to any one of claims 4 to 6, characterized in that the predetermined time in the first control is set such that vibration due to the completion of the movement of the first light-shielding member occurs after the start of the movement of the second light-shielding member.

8. The imaging apparatus according to any one of claims 4 to 7, wherein in the first control, the control means changes the predetermined time according to the operating characteristics of the electronic front curtain operation.

9. An image sensor that accumulates charge according to the amount of light received, A first light-shielding member that moves from a position that shields the image sensor to a position that retracts from it, A second light-shielding member that travels from a retracted position relative to the image sensor to a position that shields it from light, The system includes control means for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member. The control means, in each image taken during continuous imaging, after starting the movement of the first light-shielding member, starts the electronic front curtain operation and charge accumulation of the image sensor, and moves the second light-shielding member according to the set exposure time, selects, according to the conditions of continuous imaging, to perform a first control that starts the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control that starts the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The condition for continuous imaging is whether or not to allow the image sensor to accumulate display charge between images during continuous imaging. The imaging apparatus is characterized in that the control means performs the second control when the image sensor is to accumulate the display charge, and performs the first control when the image sensor is not to accumulate the display charge.

10. An image sensor that accumulates charge according to the amount of light received, A first light-shielding member that moves from a position that shields the image sensor to a position that retracts from it, A second light-shielding member that travels from a retracted position relative to the image sensor to a position that shields it from light, The system includes control means for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member. The control means, in each image taken during continuous imaging, after starting the movement of the first light-shielding member, starts the electronic front curtain operation and charge accumulation of the image sensor, and moves the second light-shielding member according to the set exposure time, selects, according to the conditions of continuous imaging, to perform a first control that starts the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control that starts the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The condition for continuous imaging is whether the vibration caused by the completion of the movement of the first light-shielding member occurs before or after the start of the electronic front curtain operation. The imaging apparatus is characterized in that the control means performs the second control if the vibration occurs before the start of the electronic front curtain operation, and performs the first control if the vibration occurs after the start of the electronic front curtain operation.

11. An imaging device having an image sensor that accumulates charge according to the amount of light received, a first light-shielding member that travels from a position that shields the image sensor to a position that retracts, and a second light-shielding member that travels from a position that retracts from the image sensor to a position that shields the image sensor, wherein a control method for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member, During each image acquisition in continuous imaging, The steps include: starting the movement of the first light-shielding member, The process includes the steps of initiating the electronic front curtain operation and charge accumulation of the image sensor, and moving the second light-shielding member according to the set exposure time, Depending on the conditions of continuous imaging, a first control is performed to start the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control is performed to start the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The conditions for continuous imaging are the continuous imaging speed or the imaging interval. A control method characterized by performing the first control when the continuous imaging speed is a first speed or the imaging interval is a first interval, and performing the second control when the continuous imaging speed is a second speed slower than the first speed or the imaging interval is a second interval longer than the first interval.

12. An imaging device having an image sensor that accumulates charge according to the amount of light received, a first light-shielding member that travels from a position that shields the image sensor to a position that retracts, and a second light-shielding member that travels from a position that retracts from the image sensor to a position that shields the image sensor, wherein a control method for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member, During each image acquisition in continuous imaging, The steps include: starting the movement of the first light-shielding member, The process includes the steps of initiating the electronic front curtain operation and charge accumulation of the image sensor, and moving the second light-shielding member according to the set exposure time, Depending on the conditions of continuous imaging, a first control is performed to start the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control is performed to start the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The condition for continuous imaging is whether or not to allow the image sensor to accumulate display charge between images during continuous imaging. A control method characterized by performing the second control when the image sensor is to accumulate the display charge, and performing the first control when the display charge is not to be accumulated.

13. An imaging device having an image sensor that accumulates charge according to the amount of light received, a first light-shielding member that travels from a position that shields the image sensor to a position that retracts, and a second light-shielding member that travels from a position that retracts from the image sensor to a position that shields the image sensor, wherein a control method for controlling the movement of the first light-shielding member, the electronic front curtain operation of the image sensor, and the movement of the second light-shielding member, During each image acquisition in continuous imaging, The steps include: starting the movement of the first light-shielding member, The process includes the steps of initiating the electronic front curtain operation and charge accumulation of the image sensor, and moving the second light-shielding member according to the set exposure time, Depending on the conditions of continuous imaging, a first control is performed to start the movement of the first light-shielding member so that it is completed after the start of the electronic front curtain operation, or a second control is performed to start the movement of the first light-shielding member so that it is completed before the start of the electronic front curtain operation. The condition for continuous imaging is whether the vibration caused by the completion of the movement of the first light-shielding member occurs before or after the start of the electronic front curtain operation. A control method characterized in that if the vibration occurs before the start of the electronic front curtain operation, the second control is performed, and if the vibration occurs after the start of the electronic front curtain operation, the first control is performed.

14. A program characterized in that it causes a computer of an imaging device having an image sensor that accumulates an electric charge corresponding to the amount of light received, a first light-shielding member that travels from a position that shields the image sensor to a position that moves away from the position that shields the image sensor to a position that shields the image sensor to execute a process according to the control method described in any one of claims 11 to 13.

Images