JP7570808B2 - Imaging device and imaging system - Google Patents

Description

The present invention relates to an imaging device to which a lens device is attached, and in particular to an imaging device with an anti-shake function.

Conventionally, imaging devices are known that reduce the effects of blurring in captured images using a sensor-shift vibration-proof method in which the imaging element is moved based on vibrations caused by the photographer's hand movement. In lens-interchangeable imaging devices, the center of the image circle may be misaligned with the center of the imaging element due to manufacturing errors, etc. In such cases, the amount of movement of the imaging element is limited, and the effects of blurring in captured images cannot be sufficiently reduced. Patent Document 1 discloses an imaging device that uses information about the image circle stored in an interchangeable lens device and information about the imaging element to move the imaging element so that the initial position of the sensor-shift vibration-proof method is the center of the image circle.

JP 2019-87937 A

However, in the imaging device of Patent Document 1, if the image circle diameter is large enough relative to the movement range of the imaging element, the amount of movement of the imaging element during image stabilization decreases in the direction in which the imaging element is moved.

The present invention aims to provide an imaging device and imaging system that can reduce the effects of blurring in captured images when the image circle diameter has a sufficient margin relative to the movement range of the image sensor.

An imaging device according to one aspect of the present invention is an imaging device to which a lens device that stores the center and radius of an image circle of an optical system is attached in a communicative manner, the imaging device having an imaging element and a control unit, the imaging element being movable in a direction including a component perpendicular to the optical axis of the optical system for image blur correction, the control unit moving the center of the imaging element to coincide with the center of the image circle when a difference value obtained by subtracting the sum of the maximum image height of the imaging element and the maximum amount of movement of the imaging element from the radius of the image circle is smaller than a threshold value set to 0 or greater, and the control unit not moving the imaging element when the difference value is greater than the threshold value.

The present invention provides an imaging device and imaging system that can reduce the effects of blurring in captured images when the image circle diameter has a sufficient margin relative to the movement range of the imaging element.

FIG. 1 is an explanatory diagram of a digital camera system as an example of an imaging system according to a first embodiment. 11 is a diagram showing the relationship between an image circle and an image sensor when the movable range of the image sensor is larger than the size of the image circle. FIG. 11A and 11B are diagrams showing the relationship between an image circle and an image sensor when the movable range of the image sensor is smaller than the size of the image circle. FIG. 13 is a diagram showing an example of an arrangement of image circle information according to the first embodiment. 4 is a flowchart showing a process executed by a camera microcomputer according to the first embodiment. FIG. 13 is a diagram showing an image circle margin. 10 is a flowchart showing a process executed by a camera microcomputer according to a second embodiment. 13A and 13B are diagrams illustrating a situation in which the image circle margin amount in the comparative example crosses a threshold value. 13A to 13C are diagrams illustrating a situation in which the image circle margin amount crosses a threshold value in the third embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings. In each drawing, the same reference numbers are used for the same components, and duplicate descriptions will be omitted.

Figure 1 is an explanatory diagram of a digital camera system 10, which is an example of an imaging system according to this embodiment. Figures 1(a) and 1(b) are a perspective view and a block diagram of the digital camera system 10, respectively.

The digital camera system 10 has an imaging device (hereafter simply referred to as camera) 100 and an interchangeable lens device (hereafter simply referred to as interchangeable lens) 200 that is removably attached to the camera 100. The camera 100 and the interchangeable lens 200 are configured to be able to communicate with each other.

In the camera 100, the image sensor 101 captures (photoelectrically converts) an image of a subject formed by the imaging optical system 210 of the interchangeable lens 200. The imaging signal output from the image sensor 101 is input to the image processing unit 107. The image processing unit 107 performs various image processes on the imaging signal to generate image data. The image data is displayed on a monitor (not shown) or recorded on a recording medium (not shown). The data storage unit (memory unit) 108 stores information related to the image sensor 101.

In the interchangeable lens 200, the imaging optical system 210 has a variable magnification lens 201, an aperture 202, and a focus lens 203. The zoom control unit 211, the aperture control unit 212, and the focus control unit 213 drive the variable magnification lens 201, the aperture 202, and the focus lens 203 in response to a zoom drive command, an aperture drive command, and a focus drive command from the camera microcomputer 102, respectively. This allows for variable magnification (zooming), light amount adjustment, and focus adjustment (focusing). The lens microcomputer 215 transmits information on the position (zoom position) of the variable magnification lens 201, the aperture diameter (aperture value) information of the aperture 202, and the position (focus position) information of the focus lens 203 to the camera microcomputer 102. The data storage unit 214 stores optical information such as the zoom range (variable range of focal length), the variable range of aperture value, and the focus range (range of distance that can be focused) of the imaging optical system 210. The data storage unit 214 also stores information (image circle information) about the image circle formed by the imaging optical system 210. Note that the image circle in this embodiment refers to an imaging area on the imaging element 101 where the amount of light is greater than 0.1 when the amount of light at the center of the image circle is 1.

The image sensor 101 is mounted on a stage (not shown) that is movable in the X and Y directions, and can move in a direction including a component perpendicular to the optical axis of the image sensor 210, which is indicated by a dashed line in FIG. 1B. The vibration detection unit 105 detects vibrations caused by the photographer's shaking or the like using a detection means such as a gyro sensor, and outputs a vibration detection signal detected by the detection means to the camera microcomputer 102. The camera microcomputer 102 calculates the amount of movement of the image sensor 101 for image blur correction (shake prevention) from the vibration detection signal, and outputs a shake prevention signal including the amount of movement to the sensor shake prevention control unit 103. The sensor shake prevention control unit 103 controls the stage and moves the image sensor 101 by the amount of movement acquired from the camera microcomputer 102, thereby performing sensor shift shake prevention. When the amount of movement of the image sensor 101 for shake prevention is x, the focal length of the image sensor 210 is f, and the hand shake angle is θ, the amount of movement x is expressed by the following formula (1).

x = f × tan θ
In other words, the larger the movement amount x, the larger the camera shake angle θ that can be corrected, which means higher image stabilization performance.

If the image sensor 101 deviates outside the image circle, the captured image will be black because almost no subject image will be projected in the deviated area (a phenomenon known as vignetting will occur), and the quality of the captured image will be reduced. Therefore, the range in which the image sensor 101 can actually move to prevent image vibration is limited to the inside of the image circle.

Figure 2 shows the relationship between the image circle 1 and the image sensor 101 when the range 5 in which the image sensor 101 can move (physically in the digital camera system 10) is larger than the size of the image circle 1.

Figure 2(a) shows an ideal state in which the center 2 of the image circle 1 and the center 4 of the image sensor 101 coincide. In this state, the range in which the image sensor 101 can move for vibration reduction is limited to the inside of the image circle 1 from the viewpoint of image quality. Therefore, the amount of movement 6 of the image sensor 101 that can be moved for vibration reduction in the diagonal direction is indicated by the arrow in the figure.

2B shows a state in which the center 2 of the image circle 1 and the center 4 of the image sensor 101 do not coincide due to manufacturing errors in the interchangeable lens 200 and the image sensor 101, and the image sensor 101 is shifted to the upper right side of the image circle 1. In this state, the range in which the image sensor 101 can move for vibration reduction is limited to the inside of the image circle 1 from the viewpoint of image quality. Therefore, the amount of movement 7 of the image sensor 101 that can be moved for vibration reduction in the diagonal upper right direction and the amount of movement 8 of the image sensor 101 that can be moved for vibration reduction in the diagonal lower right direction are indicated by arrows in the figure. The amounts of movement 7 and 8 are smaller than the amount of movement 6 of the image sensor 101 that can be moved for vibration reduction in the ideal state of FIG. 2A. In other words, in the state of FIG. 2B, the vibration reduction performance in the diagonal upper right direction and the diagonal lower right direction is deteriorated compared to the ideal state of FIG. 2A.

Figure 2(c) shows a state in which the image sensor 101 has been moved from the state in Figure 2(b) so that the initial position of the sensor-shift vibration reduction method is the center 2 of the image circle 1. In this state, the range in which the image sensor 101 can move for vibration reduction is limited to the inside of the image circle from the viewpoint of image quality. Therefore, the amount of movement 9 of the image sensor 101 that can be moved for vibration reduction in the diagonal direction is shown by the arrow in the figure. The amount of movement 9 is the same as the amount of movement 6 of the image sensor 101 that can be moved for vibration reduction in the ideal state in Figure 2(a), and vibration reduction performance can be maximized in the state of Figure 2(c).

As explained above, when the movable range 5 of the image sensor 101 is larger than the size of the image circle 1, the image sensor 101 is moved so that the initial position of the sensor-shift vibration isolation method is the center 2 of the image circle 1. This allows the vibration isolation performance of the sensor-shift vibration isolation method to be maximized.

Figure 3 shows the relationship between the image circle 1 and the image sensor 101 when the range 5 in which the image sensor 101 can move (physically in the digital camera system 10) is smaller than the size of the image circle 1.

Figure 3(a) shows an ideal state in which the center 2 of the image circle 1 coincides with the center 4 of the image sensor 101. In this state, the amount of movement 10 of the image sensor 101 that can be moved in the diagonal direction for vibration reduction is indicated by the arrow in the figure.

Figure 3(b) shows a state in which the center 2 of the image circle 1 and the center 4 of the image sensor 101 do not coincide due to manufacturing errors in the interchangeable lens 200 and the image sensor 101, causing the image sensor 101 to shift toward the upper right side of the image circle 1. In this state, the amount of movement 11 of the image sensor 101 that can be moved for vibration reduction is indicated by the arrow in the figure. The amount of movement 11 is the same as the amount of movement 10 of the image sensor 101 that can be moved for vibration reduction in the ideal state in Figure 3(a), allowing maximum vibration reduction performance to be achieved.

Figure 3(c) shows a state in which the image sensor 101 has been moved from the state in Figure 3(b) so that the initial position of the sensor-shift image stabilization method is the center 2 of the image circle 1. In this state, the amount of movement 12 of the image sensor 101 that can be moved for image stabilization in the diagonally upper left direction and the amount of movement 13 of the image sensor 101 that can be moved for image stabilization in the diagonally lower left direction are indicated by arrows in the figure. The amounts of movement 12 and 13 are smaller than the amount of movement 10 of the image sensor 101 that can be moved for image stabilization in the ideal state in Figure 3(a). In other words, in the state in Figure 3(c), the image stabilization performance in the diagonally upper left direction and the diagonally lower left direction is worse than in the ideal state in Figure 3(a).

As explained above, when the movable range 5 of the image sensor 101 is smaller than the size of the image circle 1, the image sensor 101 is not moved so that the initial position of the sensor-shift vibration isolation method is the center 2 of the image circle 1. In other words, the initial position of the sensor-shift vibration isolation method is not changed. This allows the vibration isolation performance of the sensor-shift vibration isolation method to be maximized.

The manufacturing error of the interchangeable lens 200 is the deviation of the optical axis from the axis of the lens barrel mount due to eccentricity of the optical elements that make up the imaging optical system 210, and can occur in either direction depending on the eccentricity direction of each interchangeable lens. In this embodiment, the data storage unit 214 stores image circle information measured for each interchangeable lens. The image circle information includes the center of the image circle and the radius of the image circle. The center of the image circle is the position where the absolute value of the amount of light is the largest. In addition, if the image circle is not circular, the radius of the inscribed circle of the image circle is taken as the radius of the image circle.

The center of the image circle and the radius of the image circle change depending on the optical state of the imaging optical system 210 (zoom position (zoom state), focus position (focus state), and aperture position (aperture state: open aperture, two-stop aperture, or minimum aperture)). In addition, the center of the image circle and the radius of the image circle change depending on the posture state of the camera 100 (normal position, vertical position with grip above, vertical position with grip below, or facing upwards).

The image circle information in this embodiment is data indicating the correspondence between the optical state of the imaging optical system 210 and the attitude state of the camera 100. FIG. 4 is a diagram showing an example of an arrangement of image circle information in this embodiment. In FIG. 4, the image circle information consists of the center (X, Y) of the image circle for the optical state of the imaging optical system 210 and the attitude state of the camera 100, the radius R of the image circle, and a threshold value A used to switch whether or not to perform a specified process. Note that it is sufficient that the center and radius of the image circle each correspond to at least one of the zoom state, focus state, and aperture state of the imaging optical system 210, and the attitude state of the camera 100.

The manufacturing error of the image sensor 101 is caused by dimensional tolerances of the mechanical elements constituting the camera 100, and therefore varies depending on the mechanical elements of each camera. In this embodiment, the data storage unit 108 stores information about the image sensor 101 measured for each camera. The information about the image sensor 101 includes the center of the image sensor 101, the maximum image height of the image sensor 101, and the maximum movement amount of the image sensor 101. The image height of the image sensor 101 is the maximum distance from the center of the image sensor 101 to the edge of the imaging surface in a direction perpendicular to the optical axis (half the maximum width of the imaging surface). The maximum movement amount of the image sensor 101 is the maximum movement amount that the image sensor 101 can physically move by the stage on which the image sensor 101 is mounted.

The process that the camera microcomputer 102 of this embodiment executes in accordance with the computer program (control program) will be described below with reference to FIG. 5. FIG. 5 is a flowchart showing the process that the camera microcomputer 102 of this embodiment executes.

In step S10, the camera microcontroller 102 obtains information about the image sensor 101 from the data storage unit 108.

In step S11, the camera microcomputer 102 acquires the image circle information stored in the data storage unit 214 and the optical state of the imaging optical system 210 from the lens microcomputer 215.

In step S12, the camera microcontroller 102 acquires the posture state of the camera 100 detected by the posture detection unit 104.

In step S13, the camera microcomputer 102 calculates an image circle margin (difference) Δ using information related to the image sensor 101 and image circle information, and determines whether the image circle margin Δ is greater than a threshold value A. As shown in FIG. 6, the image circle margin Δ is the difference between the radius R of the image circle and the sum of the maximum image height H of the image sensor 101 and the maximum movement amount D of the image sensor 101, and is expressed by the following formula (2).

Δ=R−(H+D)
If the image circle margin amount Δ is greater than the threshold value A, the process proceeds to step S14, and if the image circle margin amount Δ is smaller than the threshold value A, the process proceeds to step S15. If the image circle margin amount Δ is equal to the threshold value A, it is possible to arbitrarily set which step to proceed to.

In step S14, the camera microcomputer 102 does not move the image sensor 101. In other words, the initial position of the sensor-shift vibration isolation method is not changed.

In step S15, the camera microcomputer 102 moves the image sensor 101 so that the center of the image sensor 101 coincides with the center of the image circle. In other words, the initial position of the sensor-shift vibration reduction method is changed to the center of the image circle.

In step S16, the camera microcomputer 102 determines whether or not a vibration detection signal has been acquired from the vibration detection unit 105. If a vibration detection signal has been acquired, the process proceeds to step S17, and if a vibration detection signal has not been acquired, the process returns to step S11.

In step S17, the camera microcontroller 102 performs sensor vibration isolation control via the sensor vibration isolation control unit 103.

As described above, the configuration of this embodiment makes it possible to reduce the effects of blurring in captured images when the image circle diameter has a sufficient margin relative to the movement range of the image sensor.

In the digital camera system 10 of the first embodiment, it is necessary to determine the initial position of the sensor-shift vibration isolation method every time the interchangeable lens 200 is attached to the camera 100. In this embodiment, from the viewpoint of usability, the time required to determine the initial position of the sensor-shift vibration isolation method is reduced compared to the first embodiment.

The basic configuration and processing of the digital camera system 10 of this embodiment are substantially the same as those of the digital camera system 10 of embodiment 1. In embodiment 1, the interchangeable lens 200 stores information about the image circle, and the camera 100 stores information about the image sensor 101, but in this embodiment, the interchangeable lens 200 and the camera 100 each store model number information of each product in addition to the above information.

The process that the camera microcomputer 102 of this embodiment executes in accordance with the computer program (control program) will be described below with reference to FIG. 7. FIG. 7 is a flowchart showing the process that the camera microcomputer 102 of this embodiment executes.

In step S20, the camera microcontroller 102 obtains model number information of the camera 100 from the data storage unit 108.

In step S21, the camera microcomputer 102 acquires the model number information of the interchangeable lens 200 stored in the data storage unit 214 from the lens microcomputer 215.

In step S22, the camera microcomputer 102 uses the model number information of the camera 100 and the interchangeable lens 200 to determine whether the interchangeable lens 200 is a 35 mm full-frame compatible lens and the sensor size is APS-C size. If the interchangeable lens 200 is a 35 mm full-frame compatible lens, it is determined that the image circle radius is greater than 21.6 mm. Also, if the sensor size is APS-C size, it is determined that the maximum image height H of the image sensor 101 is approximately 14.7 mm. Therefore, it is determined that the image circle margin is a certain value or more, even when the maximum movement amount of the image sensor 101 is taken into account. If the interchangeable lens 200 is a 35 mm full-frame compatible lens and the sensor size is APS-C size, the process proceeds to step S23; if not, the process proceeds to step S24.

In step S23, the camera microcomputer 102 does not move the center of the image sensor 101 to the center of the image circle. In other words, the initial position of the sensor-shift vibration reduction method is not changed.

The processes from step S24 to step S31 are similar to the processes from step S10 to step S17 in FIG. 5, so detailed explanations are omitted.

As described above, according to the configuration of this embodiment, in addition to the effects of embodiment 1, the initial position of the sensor-shift vibration isolation method is determined using model number information, so that the time required from mounting the interchangeable lens 200 to the camera 100 until the initial position of the sensor-shift vibration isolation method is determined can be reduced.

The basic configuration and processing of the digital camera system 10 of this embodiment are substantially the same as those of the digital camera system 10 of embodiments 1 and 2. In embodiments 1 and 2, the initial position of the sensor-shift vibration isolation method is set to two positions based on information about the image circle stored in the interchangeable lens 200 and information about the image sensor 101 stored in the camera 100, but in this embodiment, it is set to three positions.

Figure 8 is a diagram illustrating a situation in which the image circle margin Δ crosses the threshold A while the user of the comparative example is operating the camera 100 (for example, when the optical state of the interchangeable lens 200 is changed by a zoom operation or the like). State 1 is a state in which the image sensor 101 is not moved. State 2 is a state in which the image sensor 101 is moved so that the initial position of the sensor shift vibration isolation method is the center 2 of the image circle 1. In FIG. 8(a), the state 2 transitions to state 1 at timing T1, and the state 1 transitions to state 2 at timing T2. Therefore, the image sensor 101 moves at timings T1 and T2, and the subject image may be distorted. In this embodiment, another state (intermediate state) is provided between state 1 and state 2, and when there is a possibility that the subject image may be distorted, the intermediate state is passed through when switching states. In this embodiment, when the distance between the center 2 of the image circle 1 and the center 4 of the image sensor 101 is equal to or greater than a predetermined value, it is determined that there is a possibility that the subject image may be distorted.

The processing performed by the sensor vibration isolation control unit 103 of this embodiment will be described below with reference to Fig. 9. Fig. 9 is a diagram illustrating a situation in which the image circle margin Δ crosses the threshold value A while the user of this embodiment is operating the camera 100 (for example, when an operation that changes the optical state of the interchangeable lens 200, such as a zoom operation, is performed).

State 1 is a state in which the image sensor 101 has not been moved. State 2 is a state in which the image sensor 101 has been moved so that the initial position of the sensor-shift vibration compensation method is the center 2 of the image circle 1. State 3 shows a state in which the image sensor 101 has been moved so that the initial position of the sensor-shift vibration compensation method is the middle position of the locus of the center of the image sensor 101 when the image sensor 101 transitions from state 1 to state 2. In FIG. 9(a), there is a transition from state 2 to state 3 at timing T1, and a transition from state 3 to state 1 at timing T2. There is also a transition from state 1 to state 3 at timing T3, and a transition from state 3 to state 2 at timing T4.

In this embodiment, the center of the image sensor 101 in state 3 is aligned with the midpoint of the trajectory of the image sensor 101 when it transitions from state 1 to state 2, but it may also be aligned with a position on the line connecting the original center 4 of the image sensor 101 and the center 2 of the image circle 1.

As described above, according to the configuration of this embodiment, in addition to the effect of embodiment 1, by providing another state (intermediate state) between state 1 and state 2 and switching via that intermediate state, it is possible to prevent distortion of the subject image.

In this embodiment, the case where an intermediate state is passed through when switching states is described, but the same effect can be obtained by setting the amount of movement of the image sensor 101 per unit time to a predetermined value or less.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments, and various modifications and variations are possible within the scope of the gist of the invention.

100 Imaging device 101 Imaging element 102 Camera microcomputer (control unit)
200 Interchangeable lens device (lens device)
210 Imaging optical system (optical system)

Claims (7)

An imaging device to which a lens device that stores the center and radius of an image circle of an optical system is communicatively attached,
The imaging device includes an imaging element and a control unit.
the imaging element is movable in a direction including a component perpendicular to an optical axis of the optical system for image blur correction;
when a difference value obtained by subtracting the sum of the maximum image height of the image sensor and the maximum amount of movement of the image sensor from a radius of the image circle is smaller than a threshold value set to be equal to or greater than 0, the control unit moves a center of the image sensor to coincide with a center of the image circle;
The imaging apparatus according to claim 1, wherein the control unit does not move the imaging element when the difference value is greater than the threshold value. The imaging device according to claim 1, characterized in that, when the difference value is smaller than the threshold value and the distance between the center of the image circle and the center of the imaging element is equal to or greater than a predetermined value, the control unit moves the imaging element so that the center of the imaging element coincides with a position on a line connecting the center of the imaging element and the center of the image circle, and then moves the imaging element so that the center of the imaging element coincides with the center of the image circle. The imaging device according to claim 1 or 2, characterized in that the amount of movement of the imaging element per unit time is equal to or less than a predetermined value. The imaging device according to any one of claims 1 to 3, characterized in that the control unit uses model number information of the lens device and model number information of the imaging device to determine whether to move the imaging element. The imaging device according to any one of claims 1 to 4, further comprising a storage unit that stores the center, maximum image height, and maximum movement amount of the imaging element. The imaging device according to any one of claims 1 to 5, characterized in that the center and radius of the image circle correspond to at least one of the zoom state, focus state, and aperture state of the optical system, and the attitude state of the imaging device. a lens arrangement for storing the center and radius of an image circle of the optical system;
An imaging system comprising the imaging device according to claim 1 .