JP5391587B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus.

  In an imaging apparatus such as a digital camera, focus adjustment is performed by moving a focus adjustment lens. In such an imaging apparatus, in order to increase the focus adjustment accuracy, a technique for adjusting the focus by moving the imaging surface of the image sensor in addition to the movement of the focus adjustment lens is known (for example, Patent Document 1). reference).

JP 2007-11021 A

  However, in the case of an optical finder type camera such as a single-lens reflex digital camera, an image picked up by an image pickup device and an image by an observation optical system such as a viewfinder are independent. There is a problem that the photographer cannot confirm the state of the image when the focus is adjusted by moving the lens.

  The problem to be solved by the present invention is to provide an imaging apparatus that allows a photographer to check a change in the state of an image when the imaging means is moved.

  The present invention solves the above problems by the following means. In addition, although the code | symbol corresponding to drawing which shows embodiment of this invention is attached | subjected and demonstrated, this code | symbol is only for making an understanding of invention easy, and is not the meaning which limits invention.

The invention according to claim 1 includes an imaging unit (110) that captures an image by the imaging optical system (211), an observation optical system (134) that forms an image for a photographer to observe, and the imaging optical system. A quick return mirror (121) capable of switching between a first position for guiding a light beam in a first direction and a second position for guiding a light beam by the photographing optical system in a second direction intersecting the first direction; and a pentaprism , A transmission type display (132) for displaying the shape of the focus detection area in a superimposed manner, and an image of a light beam guided in the second direction by the quick return mirror, and the focus detection area , A focusing screen (131) that can be driven independently of the pentaprism and the transmissive display, a defocus calculation unit that calculates a defocus amount, and the default A first driving amount that is a driving amount of the photographing optical system is calculated based on the defocus amount calculated by a scanning calculating unit, and a second driving amount that is a driving amount of the imaging unit is calculated based on the defocus amount. A third driving amount that is a driving amount of the focusing screen is calculated based on the second driving amount, and a fourth driving amount that is a driving amount of the observation optical system is calculated based on the third driving amount. A driving amount calculating unit that calculates the first driving amount, the first driving control unit that drives and controls the photographing optical system in the first direction using the first driving amount, and the imaging unit that uses the second driving amount. Third drive control for driving and controlling the focusing screen in the second direction without driving the transmissive display using a second drive control unit for driving and controlling in the first direction and the third drive amount. And the optical axis of the observation optical system using the fourth drive amount A fourth drive controller for controlling the direction, which is an imaging apparatus which comprises a.

According to a second aspect of the present invention, in the imaging apparatus according to the first aspect, the second drive control unit is configured to perform drive control of the photographing optical system in the first direction by the first drive control unit. An image pickup apparatus that controls the drive of the image pickup unit in the first direction.

According to a third aspect of the present invention, in the imaging apparatus according to the first or second aspect, the second drive control unit returns the position of the imaging unit to an initial state with the activation of the defocus calculation unit. It is the imaging device characterized.

According to a fourth aspect of the present invention, in the imaging apparatus according to any one of the first to third aspects, the third drive control unit sets the position of the focusing screen to an initial state as the defocus calculation unit is activated. The imaging device is characterized by being returned.

According to a fifth aspect of the present invention, in the imaging apparatus according to any one of the first to fourth aspects, the fourth drive control unit sets the position of the observation optical system in an initial state as the defocus calculation unit is activated. It is an imaging device characterized by returning to.

  According to the above invention, the photographer can confirm the change in the state of the image when the imaging means is moved.

  In the following, an embodiment in which the above invention is applied to a single-lens reflex digital camera will be described with reference to the drawings. However, the above invention can also be applied to other imaging devices such as a silver salt film camera.

  FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to the present embodiment. The illustration and description of a general configuration of the camera other than the configuration related to the lens barrel and the imaging apparatus of the invention are partially omitted. To do.

  The single-lens reflex digital camera 1 of this embodiment (hereinafter simply referred to as the camera 1) includes a camera body 100 and a lens barrel 200, and the camera body 100 and the lens barrel 200 are detachably coupled.

  The lens barrel 200 incorporates a photographing optical system including a lens group 210 including a focus lens 211 and a zoom lens 212, an aperture device 220, and the like.

  The focus lens 211 is provided so as to be movable along the optical axis L <b> 1, and its position is adjusted by the focus lens driving motor 230 while its position is detected by the focus lens encoder 260. Then, the position information of the focus lens 211 detected by the focus lens encoder 260 is transmitted to the lens drive control unit 165 described later via the lens control unit 250. The focus lens drive motor 230 is driven by a drive signal transmitted from the lens drive control unit 165 via the lens control unit 250 in accordance with a lens drive amount Δd1 calculated based on a focus detection result described later.

  The aperture device 220 is adjustable in its aperture diameter around the optical axis L1 in order to limit the amount of light beam that passes through the photographing optical system and reaches the image sensor 110. The aperture diameter is adjusted by the aperture device 220 by, for example, transmitting a signal corresponding to the aperture value calculated in the automatic exposure mode from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250. . The aperture diameter is adjusted by a manual operation by the operation unit 150 provided in the camera body 100, and a signal corresponding to the set aperture value is transmitted from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250. This is also done by sending it.

  The lens barrel 200 is provided with a lens control unit 250. The lens control unit 250 includes a microprocessor and peripheral components such as a memory, and is electrically connected to the camera control unit 170. The lens control unit 250 receives information such as a defocus amount and an aperture control signal from the camera control unit 170. The lens information is transmitted to the camera control unit 170.

  On the other hand, the camera body 100 includes a mirror system 120 for guiding the light flux from the subject to the image sensor 110, the finder 135, the photometric sensor 137, and the focus detection module 161. The mirror system 120 includes a quick return mirror 121 that rotates by a predetermined angle between the observation position and the photographing position of the subject around the rotation axis 123, and the quick return mirror 121 that is pivotally supported by the quick return mirror 121. And a sub mirror 122 that rotates in accordance with the rotation. In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the photographing position of the subject is indicated by a two-dot chain line.

  The mirror system 120 is inserted on the optical path of the optical axis L1 in the state where the subject is in the observation position, while rotating so as to retract from the optical path of the optical axis L1 in the state where the subject is in the photographing position.

  The quick return mirror 121 is composed of a half mirror, and in a state where the subject is at the observation position, the quick return mirror 121 reflects a part of the light flux (optical axes L2 and L3) from the subject (optical axis L1). Then, the light is guided to the finder 135 and the photometric sensor 137, and a part of the light beam (optical axis L4) is transmitted and guided to the sub mirror 122. On the other hand, the sub mirror 122 is configured by a total reflection mirror, and guides the light beam (optical axis L4) transmitted through the quick return mirror 121 to the focus detection module 161.

  Therefore, when the mirror system 120 is at the observation position, the light flux (optical axis L1) from the subject is guided to the finder 135, the photometric sensor 137, and the focus detection module 161, and the subject is observed by the photographer and exposure calculation is performed. And the focus adjustment state of the focus lens 211 is detected. Then, when the photographer fully presses the release button, the mirror system 120 rotates to the photographing position, and all the luminous flux (optical axis L1) from the subject is guided to the image sensor 110, and the photographed image data is stored in a memory (not shown). To do.

  The focus detection module 161 is a focus detection element for performing automatic focusing control by a phase difference detection method using subject light, and the imaging element 110 of the light beam (optical axis L4) reflected by the sub mirror 122 is the initial position. In this case, it is fixed at a position optically equivalent to the image pickup surface of the image pickup device 110.

  FIG. 2 is a diagram illustrating a configuration example of the focus detection module 161 illustrated in FIG.

  The focus detection module 161 of this example includes a condenser lens 161a, a diaphragm mask 161b having a pair of apertures, a pair of re-imaging lenses 161c, and a pair of line sensors 161d. The focus adjustment state is detected by obtaining a phase shift of a pair of image signals obtained by receiving a pair of light fluxes passing through the region by a line sensor 161d by a known correlation calculation.

  As shown in FIG. 2, when the subject P is imaged on the equivalent surface (scheduled imaging surface) 161e of the image sensor 110, the focused state is obtained. However, the focus lens 211 moves in the direction of the optical axis L1, and the result is as follows. If the image point shifts from the equivalent surface 161e toward the subject (referred to as a front pin) or shifts toward the camera body 100 (referred to as a rear pin), a focus shift state occurs.

  When the imaging point of the subject P is shifted from the equivalent surface 161e toward the subject, the interval W between the pair of image signals detected by the pair of line sensors 161d becomes shorter than the interval W in the focused state, and vice versa. If the imaging point of the subject image P is shifted to the camera body 100 side, the interval W between the pair of image signals detected by the pair of line sensors 161d becomes longer than the interval W in the focused state.

  That is, in the in-focus state, the image signals detected by the pair of line sensors 161d overlap with the center of the line sensor, but in the out-of-focus state, each image signal is shifted from the center of the line sensor, that is, the phase difference is Therefore, the focus lens 211 and the image sensor 110 are moved by an amount corresponding to the phase difference (deviation amount) to focus.

  Returning to FIG. 1, the AF-CCD control unit 162 controls the gain and accumulation time of the line sensor 161 d of the focus detection module 161 in the autofocus mode, and stores information on the focus detection area selected as the focus detection position. A pair of image signals received from the camera control unit 170 and detected by the pair of line sensors 161 d corresponding to the focus detection area are read and output to the defocus calculation unit 163.

  The defocus calculation unit 163 converts the shift amount of the pair of image signals sent from the AF-CCD control unit 162 into a defocus amount df, and outputs this to the drive amount calculation unit 164.

  Based on the defocus amount df sent from the defocus calculation unit 163, the drive amount calculation unit 164 calculates a lens drive amount Δd1 and an image sensor drive amount Δd2 corresponding to the defocus amount df. Then, the lens drive amount Δd1 is output to the lens drive control unit 165, and the image sensor drive amount Δd2 is output to the camera control unit 170. Note that the image pickup element drive amount Δd2 is a follow-up adjustment amount. When determining the lens drive amount Δd1 and the image pickup element drive amount Δd2, first, the lens drive amount Δd1 is determined based on the movement accuracy of the focus lens 211. . Next, in accordance with the lens driving amount Δd1, taking into consideration the movement accuracy of the imaging device 110, the image pickup device driving amount Δd2 that is the follow-up adjustment amount is determined.

  The lens drive controller 165 sends a drive command to the lens drive motor 230 based on the lens drive amount Δd1 sent from the drive amount calculator 164, and moves the focus lens 211 by the lens drive amount Δd1.

  The image sensor 110 is provided on the camera body 100 on the optical axis L1 of the light beam from the subject and at a position that is a planned focal plane of the photographing optical system including the lens group 210, and a shutter 111 is provided on the front surface thereof. ing. The image sensor 110 is a two-dimensional array of a plurality of photoelectric conversion elements, and can be constituted by a two-dimensional CCD image sensor, a MOS sensor, a CID, or the like. The electrical image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

  The image sensor 110 is movable along the optical axis L1, and its position is adjusted by the image sensor drive motor 181 while its position is detected by an image sensor encoder (not shown). Then, the position information of the image sensor 110 detected by the image sensor encoder is transmitted to the defocus calculation unit 163 via the camera control unit 170. Further, the image sensor driving motor 181 is driven by a drive signal transmitted from the camera control unit 170 according to the image sensor driving amount Δd2 calculated based on the focus detection result.

  On the other hand, the light flux from the subject reflected by the quick return mirror 121 forms an image on the focusing screen 131 and is guided to the photographer's eyeball via the pentaprism 133 and the eyepiece lens 134.

  The focusing screen 131 is movably provided along the optical axes L2 and L3 by a focusing screen drive motor 182. The focusing screen drive motor 182 is driven in accordance with the focusing screen drive amount Δd3 transmitted from the camera control section 170, whereby the focusing screen 131 is imaged so as to be positioned on a surface optically equivalent to the imaging device 110. It moves along the optical axes L2 and L3 according to the amount of movement of the element 110.

  The transmissive liquid crystal display 132 superimposes and displays a focus detection area mark on the subject image on the focusing screen 131 and displays information relating to shooting such as the shutter speed, aperture value, and number of shots in an area outside the subject image. To do. Thereby, in the shooting preparation state, the subject, its background, shooting related information, and the like can be observed through the finder 135.

  The eyepiece lens 134 is a lens for guiding the subject image formed on the focusing screen 131 and information relating to photographing displayed on the transmissive liquid crystal display 132 to the photographer's eyeball. , So as to be movable along the optical axis L2. The eyepiece driving motor 183 is driven according to the eyepiece driving amount Δd4 transmitted from the camera control unit 170, whereby the eyepiece 134 adjusts the diopter according to the movement of the focusing screen 131. It moves along the optical axis L2.

  The operation unit 150 is a shutter release button, a zoom button, and an input switch for the photographer to set various operation modes of the camera 1, and switches between automatic exposure mode / manual exposure mode, auto focus mode / manual focus mode, Even in the auto focus mode, switching between the one-shot mode / continuous mode can be performed.

  The shutter release button is turned on when the shutter release button is fully pressed, but in addition to this, when the button is pressed halfway in the autofocus mode, the focusing operation by the focus lens 211 and the image sensor 110 is turned on, and the button is pressed. When released, it turns OFF. A single / continuous shooting setting button is also included, and a predetermined number of images can be taken per second when the release button is fully pressed in the continuous shooting mode.

The camera body 100 is provided with a camera control unit 170. The camera control unit 170 includes a microprocessor and peripheral components such as a memory, and is electrically connected to the lens control unit 250. The camera control unit 170 receives lens information from the lens control unit 250. Information such as an aperture control signal is transmitted. The camera control unit 170 reads out image information from the image sensor 110 as described above, performs predetermined information processing as necessary, and outputs the information to a memory (not shown). Furthermore, the camera control unit 170 calculates the focusing screen drive amount Δd3 and the eyepiece lens drive amount Δd4 based on the imaging element drive amount Δd2 output from the drive amount calculation unit 164. Then, according to the imaging element driving amount Δd2, the focusing screen driving amount Δd3, and the eyepiece driving amount Δd4, a driving signal is transmitted to the imaging element driving motor 181, the focusing screen driving motor 182 and the eyepiece driving motor 183, respectively.
In addition to these, the camera control unit 170 controls the entire camera 1 such as correction of captured image information and detection of a focus adjustment state and an aperture adjustment state of the lens barrel 200.

  In the vicinity of the eyepiece lens 134, a photometric lens 136 and a photometric sensor 137 are provided to receive part of the subject light imaged on the focusing screen 131.

  The photometric sensor 137 of this example is composed of a two-dimensional color CCD image sensor or the like, and outputs a photometric signal corresponding to the luminance of the received light flux to the camera control unit 170 for each predetermined pixel group, and an image sensor for photographing. An exposure value of 110 is calculated. A photometric signal for each pixel or predetermined pixel group by the photometric sensor 137 is output to the camera control unit 170 and used for analysis and recognition of a shooting scene, and the position of a focus adjustment target based on luminance and color. Is used for various image processing, or for selecting a shooting mode such as portrait shooting or landscape shooting.

Next, the operation of the camera 1 of this example will be described.
FIG. 3 is a flowchart showing an operation example of the camera 1 of this example.

  First, in step S1, when the photographer presses the release button halfway in the autofocus mode, the focus detection module 161 is activated. As the focus detection module 161 is activated, the image sensor motor 181 is driven to return the position of the image sensor 110 on the optical axis L1 to the initial position. Similarly, the focusing screen drive motor 182 and the eyepiece lens driving motor 183 are driven to return the position of the focusing screen 131 on the optical axes L2 and L3 and the position of the eyepiece lens 134 on the optical axis L2 to the initial positions.

  In step S2, the focus detection state of the optical system is detected by the focus detection module 161, the AF-CCD control unit 162, and the defocus calculation unit 163, the amount of shift of the image signal is calculated from the focus adjustment state, and the shift of the image signal is detected. The defocus amount df is calculated from the amount.

  In step S3, the drive amount calculation unit 164 compares the defocus amount df with a predetermined value Th1. As a result, if df ≦ Th1, the process proceeds to step S5, whereas if df> Th1, the process proceeds to step S4. The predetermined value Th1 is not particularly limited and may be set according to the movement accuracy of the focus lens 211. Usually, the minimum movable distance (minimum unit that can be moved) of the focus lens 211, or the minimum movable distance. A slightly larger value.

  In step S4, the drive amount calculation unit 164 calculates the lens drive amount Δd1 from the defocus amount df, and outputs the lens drive amount Δd1 to the lens drive control unit 165. Then, the lens drive control unit 165 sends a drive command to the lens drive motor 230 based on the lens drive amount Δd1, and moves the focus lens 211 by the lens drive amount Δd1. After moving the focus lens 211, the process returns to step S2, and the defocus amount df is calculated again.

  In step S <b> 5, the drive amount calculation unit 164 calculates the image sensor drive amount Δd <b> 2 from the defocus amount df detected in step S <b> 2 and outputs it to the camera control unit 170. Then, the camera control unit 170 sends a drive command to the image sensor drive motor 181 based on the image sensor drive amount Δd2, moves the image sensor 110 along the optical axis L1 by the image sensor drive amount Δd2, and sets the image plane position. Move.

  In step S <b> 6, the camera control unit 170 calculates a focusing screen driving amount Δd <b> 3 corresponding to the imaging element driving amount Δd <b> 2, and outputs this to the focusing screen drive motor 182. Then, the focusing screen drive motor 182 is driven according to the focusing screen drive amount Δd3, and thereby the moving amount of the image sensor 110 is set so that the focusing screen 131 is positioned on a surface optically equivalent to the image sensor 110. Accordingly, the optical axis is moved along the optical axes L2 and L3. Note that the focusing screen drive amount Δd3 is normally the same as the imaging device driving amount Δd2 so that the imaging surface on the focusing screen 131 is positioned on a surface optically equivalent to the imaging surface of the imaging device 110. In addition, when the camera control unit 170 calculates the focusing screen drive amount Δd3, instead of calculating according to the image sensor drive amount Δd2 calculated by the drive amount calculation unit 164, the imaging provided in the image sensor 110 is performed. You may calculate based on the position after the movement of the image pick-up element 110 detected by the element encoder (illustration omitted).

  In step S <b> 7, the camera control unit 170 calculates an eyepiece lens driving amount Δd <b> 4 corresponding to the focusing screen driving amount Δd <b> 3 and outputs this to the eyepiece lens driving motor 183. Then, the eyepiece lens driving motor 183 is driven according to the lens driving amount Δd4, whereby the eyepiece lens 134 is adjusted to the amount of movement of the focusing screen 131 in order to adjust the diopter according to the movement of the focusing screen 131. Accordingly, the optical axis is moved along the optical axes L2 and L3.

  The movement of the image sensor 110 (step S5), the movement of the focusing screen 131 (step S6), and the eyepiece lens 134 (step S7) are not necessarily performed in the above order, and may be performed in a different order. Moreover, you may carry out simultaneously.

  In step S8, the focus detection module 161, the AF-CCD control unit 162, and the defocus calculation unit 163 detect the focus adjustment state of the optical system, calculate the shift amount of the image signal from the focus adjustment state, and shift the image signal. The defocus amount df is calculated from the amount. In step S8, when the defocus calculation unit 163 calculates the defocus amount df, the defocus calculation unit 163 detects the image sensor detected by the image sensor encoder (not shown) provided in the image sensor 110. The position after the movement of 110 is acquired via the camera control unit 170, and the defocus amount df is calculated in consideration of the position after the movement of the image sensor 110.

  In step S9, the drive amount calculation unit 164 compares the defocus amount df with a predetermined value Th2 (which has a relationship of Th2 <Th1). As a result, when df ≦ Th2, it is determined that the focus is achieved, and the autofocus is terminated. On the other hand, if df> Th2, the process returns to step S5, and the image sensor 110, the focusing screen 131, and the eyepiece lens 134 are moved based on the defocus amount df detected in step S8. Note that the predetermined value Th2 is not particularly limited and may be set according to the movement accuracy of the image sensor 110. Usually, the minimum movable distance (the minimum unit that can be moved) of the image sensor 110, or the minimum movable distance. A slightly larger value.

  As described above, according to the camera 1 of the present example, when the image pickup device 110 is moved and the image pickup surface position is changed to adjust the tracking, the focusing screen 131 is moved according to the amount of movement of the image pickup device 110. Therefore, the focus adjustment accuracy can be improved, and the photographer can confirm the effect of the follow-up adjustment (change in the image formation state of the image) by changing the imaging surface position through the eyepiece lens 134. .

  The embodiment described above is described for facilitating the understanding of the invention, and is not described for limiting the invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the above invention.

  In the camera 1 of this example, instead of making the focusing screen 131 movable, an observation optical system imaging lens 190 indicated by a dotted line in FIG. It is good also as a structure which adjusts the image imaged on the focusing screen 131 by moving along the optical axes L2 and L3 by (illustration omitted).

  Further, in the camera 1 of this example, in addition to the focus adjustment using the focus detection module 161, a pair of focus detection pixels are provided in the array of pixels constituting the image sensor 110, and the pupils of the lens groups 210 are different. It is also possible to use automatic focus adjustment by a pupil division phase difference method that detects a focus position based on a difference in imaging position between a pair of light beams that have passed through the region. In this case, the phase difference can be directly detected regardless of the position of the image sensor 110 on the optical axis L1.

FIG. 1 is a main part configuration diagram showing a single-lens reflex digital camera according to the present embodiment. It is a figure which shows the focus detection module of FIG. 3 is a flowchart illustrating an operation example of the camera of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Single-lens reflex digital camera 100 ... Camera body 110 ... Imaging device 131 ... Focus plate 134 ... Eyepiece lens 161 ... Focus detection module 170 ... Camera control part 181 ... Imaging device drive motor 182 ... Focus plate drive motor 183 ... Eyepiece drive motor 200 ... Lens barrel 210 ... Lens group 220 ... Aperture device 230 ... Focus lens drive motor 240 ... Aperture drive device 250 ... Lens control unit 260 ... Focus lens encoder

Claims (5)

An imaging unit that captures an image by the imaging optical system;
An observation optical system for forming an image for the photographer to observe;
A quick return mirror capable of switching between a first position for guiding a light beam by the photographing optical system in a first direction and a second position for guiding the light beam by the photographing optical system in a second direction intersecting the first direction;
A transmission type display provided near the pentaprism for superimposing and displaying the shape corresponding to the focus detection area;
An image of the light beam guided in the second direction by the quick return mirror is formed, and the shape corresponding to the focus detection area is superimposed and displayed, and can be driven independently of the pentaprism and the transmissive display A focusing screen,
A defocus calculation unit for calculating a defocus amount;
A first driving amount that is a driving amount of the photographing optical system is calculated based on the defocus amount calculated by the defocus calculating unit, and a second driving that is a driving amount of the imaging unit is calculated based on the defocus amount. A third driving amount that is a driving amount of the focusing screen is calculated based on the second driving amount, and a fourth driving amount that is the driving amount of the observation optical system is calculated based on the third driving amount. A drive amount calculation unit for calculating the drive amount;
A first drive control unit that drives and controls the photographing optical system in the first direction using the first drive amount;
A second drive control unit that drives and controls the imaging unit in the first direction using the second drive amount;
A third drive control unit that drives and controls the focusing screen in the second direction without driving the transmissive display using the third drive amount;
An imaging apparatus comprising: a fourth drive control unit that drives and controls the observation optical system in the optical axis direction of the observation optical system using the fourth drive amount. The imaging device according to claim 1,
The second drive control unit drives and controls the imaging unit in the first direction after drive control of the imaging optical system in the first direction is performed by the first drive control unit. An imaging device. The imaging device according to claim 1 or 2,
The second drive control unit returns the position of the imaging unit to an initial state in accordance with the activation of the defocus calculation unit. In the imaging device in any one of Claims 1-3,
The third drive control unit returns the position of the focusing screen to an initial state in accordance with the activation of the defocus calculation unit. In the imaging device according to any one of claims 1 to 4,
The fourth drive control unit returns the position of the observation optical system to an initial state in accordance with the activation of the defocus calculation unit.

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