JP2011013555A - Camera-shake correction device and optical instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera-shake correction device capable of achieving suitable camera-shake correction.SOLUTION: The camera-shake correction device includes: a camera-shake detection part (20) outputting a detection signal including a camera-shake component corresponding to a camera-shake and a posture component corresponding to a posture; a posture detection part (18) detecting the posture of the camera-shake detection part and outputting a posture signal; a calculation part (8) calculating a camera-shake correction signal for correcting the camera-shake by using the detection signal and the posture signal; and a drive part (28) performing drive so as to correct the camera-shake on the basis of the camera-shake correction signal.

Description

  The present invention relates to a shake correction apparatus and an optical apparatus.

  Conventionally, in the camera shake correction of a digital camera, a method of acquiring a shake correction signal by correcting an offset component in an output of a shake detection unit has been proposed. However, depending on the type of the shake detection unit, the offset component may fluctuate rapidly due to the change in posture, and the accuracy of the shake correction signal may deteriorate immediately after the change in the posture of the shake detection unit. .

Japanese Patent Laid-Open No. 10-228043

  An object of the present invention is to realize a shake correction apparatus capable of realizing a preferred shake correction.

In order to achieve the above object, a shake correction apparatus according to the present invention includes:
A blur detection unit (20) that outputs a detection signal including a blur component corresponding to blur and a posture component corresponding to posture;
A posture detection unit (18) for detecting the posture of the blur detection unit and outputting a posture signal;
A calculation unit (8) for calculating a shake correction signal for correcting shake using the detection signal and the attitude signal;
And a drive unit (28) that is driven to correct blur based on the blur correction signal.

  The calculation unit (8) may calculate the blur correction signal using the detection signal and the posture signal so that the influence of the posture component of the detection signal is reduced. The calculation unit (8) calculates from the detection signal so that the influence of the posture component that is one of the components of the detection signal is reduced, so that the posture component that is an error component is calculated from the detection signal. It is possible to correct the shake by acquiring the canceled shake correction signal.

  The calculation unit (8) reduces the detection signal so as to cancel the change in the posture component accompanying the change in the posture of the shake detection unit (20) when the posture of the shake detection unit (20) changes. You may let them. The calculation unit (8) reduces the detection signal so as to cancel out a change in the posture component that is one of the components of the detection signal from the detection signal, thereby reducing the error component from the detection signal. It is possible to correct the shake by acquiring an accurate shake correction signal in which the posture component is canceled.

  The calculation unit (8a) includes a reference value calculation unit (312a) that calculates a reference value including a low frequency component of the detection signal, and uses the difference between the detection signal and the reference value to calculate the blur correction signal. May be calculated. The reference value calculation unit (312a) calculates the shake correction signal using the difference between the detection signal and the reference value, thereby obtaining an accurate shake correction signal from which the posture component has been subtracted. It can be corrected.

  The calculation unit (8a) may reduce the time constant of the reference value when the posture of the shake detection unit (20) changes. In accordance with the change in the posture of the shake detection unit (20), the time constant of the reference value is reduced to change the change in the posture of the shake detection unit (20). It is possible to correct the shake by obtaining a shake correction signal having a good response to the change in the detection signal.

  The posture detection unit (18) detects an acceleration of the blur detection unit (20), and detects the posture of the blur detection unit (20) based on an output signal of the acceleration sensor (501). An attitude determination unit (506) that determines and outputs the attitude signal may be included.

  The posture detection unit (18) may detect a posture around an axis in a direction intersecting with the direction of the blur component. The posture detection unit (18) can detect the shooting posture by detecting the posture around the axis in the direction intersecting the direction of the blur component.

The drive unit (28) has an optical member for correcting image blur,
The optical member may be at least one of an optical system (26) that transmits light and an imaging unit (10) that captures an image of light.

  An optical apparatus according to the present invention includes any of the shake correction apparatuses described above.

  In the above description, in order to explain the present invention in an easy-to-understand manner, the description has been made in association with the reference numerals of the drawings illustrating the embodiments, but the present invention is not limited to this. The configuration of the embodiment described later may be improved as appropriate, or at least a part of the configuration may be replaced with another component. Further, the configuration requirements that are not particularly limited with respect to the arrangement are not limited to the arrangement disclosed in the embodiment, and can be arranged at a position where the function can be achieved.

FIG. 1 is a schematic configuration diagram of a camera according to an embodiment of the present invention. FIG. 2 is a diagram illustrating output fluctuation due to a gyro attitude difference. FIG. 3 is a functional block diagram of the invention according to an embodiment of the present invention. FIG. 4 is a diagram illustrating the effect of the gyro attitude difference on blur correction. FIG. 5 is a functional block diagram showing the details of one embodiment of the present invention shown in FIG. FIG. 6 is a diagram showing that the influence of the gyro attitude difference is improved by the embodiment shown in FIG. 5. FIG. 7 is a functional block diagram of an invention according to another embodiment of the present invention. FIG. 8 is a diagram showing that the influence of the gyro attitude difference is improved by the embodiment shown in FIG.

First Embodiment First, an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic configuration diagram of a digital camera 101 including a shake correction apparatus according to an embodiment of the present invention. The digital camera 101 includes a camera body unit 102 provided with an image sensor 10 and the like, and a lens barrel unit 103 provided with a lens and the like.

  The camera main body 102 includes a CPU 8, an image sensor 10, a signal processing circuit 12, an acceleration sensor 501, a release switch 14, an AF sensor 16, a recording medium 4, an EEPROM 6, and a rear liquid crystal 2.

  The release switch 14 is a push button switch operated by the photographer and functions as an input unit. The release switch 14 can be operated in two stages: a half-press operation (first release operation) and a full-press operation (second release operation). The release switch 14 outputs a half-press signal to the CPU 8 in response to the photographer's half-press operation, and outputs a full-press signal to the CPU 8 in response to the photographer's full-press operation.

  The image sensor 10 is a solid-state image sensor such as a CCD or CMOS. The image sensor 10 photoelectrically converts light incident on the image sensor 10 via the lens barrel 103 and outputs an image signal to the signal processing circuit 12. The signal processing circuit 12 performs noise processing, A / D conversion, and the like on the image signal input from the image sensor 10 and outputs the result to the CPU 8.

  The CPU 8 controls the entire camera, such as shooting preparation operations such as zooming and focusing, and exposure operations. For example, the CPU 8 controls the focus lens group driving mechanism 32 provided in the lens barrel 103 based on the distance information from the AF sensor 16 and the like when there is an input signal of a half-press operation from the release switch 14, and the focus Focusing control is performed by changing the position of the lens group 30 and the like.

  The recording medium 4 is composed of a nonvolatile storage medium such as a flash memory, a magnetic disk, or an optical disk. The recording medium 4 is controlled by the CPU 8 and stores image data and the like based on the image signal from the image sensor 10.

  The memory 6 is composed of a nonvolatile storage medium such as a flash memory, a magnetic disk, or an optical disk. The memory 6 stores adjustment value data such as a gain value of the gyro 20.

  A rear liquid crystal 2 is provided on the rear surface of the housing of the camera body 102. The rear liquid crystal 2 displays a live view based on an image signal from the image sensor 10 and image data stored in the recording medium 4 by the CPU 8.

  The attitude sensor 18 includes an acceleration sensor, a geomagnetic sensor, and the like. The attitude sensor 18 detects the attitude of the gyro 20 and outputs an attitude signal to the CPU 8.

  The lens barrel 103 includes lens groups such as a blur correction lens group 26, a focus lens group 30, and a zoom lens group 34, a shutter / diaphragm unit 22, and drive mechanisms 24, 28, which drive these optical components. 32, 36, etc. are provided.

  The zoom lens group 34 moves along the optical axis L of the camera when adjusting the magnification of the camera. The zoom lens group driving mechanism 36 adjusts the zoom magnification of the camera by moving the zoom lens group 34 and the like according to a control signal from the CPU 8 and the like.

  The focus lens group 30 moves along the optical axis L of the camera when performing camera focus adjustment. The focus lens group drive mechanism 32 moves the focus lens group 30 and the like in accordance with a control signal from the CPU 8 to adjust the focus of the camera.

  The shutter / diaphragm 22 is an optical component that controls the exposure time and the exposure amount. The shutter / aperture unit 22 is driven by a shutter / aperture drive mechanism 24 in accordance with a control signal from the CPU 8.

  The lens barrel 103 includes a blur correction lens group 26 for correcting image blur based on camera shake or the like. The blur correction lens group 26 is held so as to be movable in a direction orthogonal to the optical axis L of the camera. The CPU 8 controls the shake correction lens group driving mechanism 28 and the like based on the detection signal output from the gyro 20 provided in the lens barrel 103. Here, the detection output output by the gyro 20 is hereinafter referred to as a blur signal. The CPU 8 can adjust the control amount and the like using the gain value of the gyro 20 stored in the memory 6 when controlling the blur correction lens group driving mechanism 28 and the like.

  The gyro 20 detects image blur due to camera shake of the photographer and outputs a blur signal including a blur component corresponding to the image blur to the CPU 8. The output voltage of the gyro 20 may change due to a change in posture, and the shake signal includes a posture component corresponding to the posture of the gyro 20 in addition to the shake component. FIG. 2 illustrates how the shake signal output from the gyro 20 changes in accordance with the attitude of the gyro 20. In FIG. 2, when the direction of the detection axis of the gyro changes from the A direction to the B direction at the timing of time t1, the DC component of the shake signal fluctuates.

  Next, based on the functional block diagram shown in FIG. 3, the flow of acquiring the shake correction signal ω in which the influence of the posture component of the shake signal is reduced from the shake signal acquired by the gyro 20 will be described. Although not described in FIG. 1, the blur signal output by the gyro 20 is input to the CPU 8 via the low-pass filter 302, the offset voltage adjustment unit 304, and the A / D converter 306. The low-pass filter 302 attenuates a noise component in a high frequency band that is not related to camera shake from the signal component of the shake signal. The blur signal in which noise in the high frequency band is attenuated is adjusted in offset voltage by the offset voltage adjustment unit 304 and quantized by the A / D conversion unit 306. Hereinafter, this quantized blur signal is referred to as a camera shake signal ω1.

  The quantized camera shake signal ω <b> 1 is input to the high pass filter 310. The high pass filter 310 removes an offset output composed of the posture component of the camera shake signal ω1 and the offset voltage component adjusted by the offset voltage adjustment unit 304 from the camera shake signal ω1, and only the camera shake component of the camera shake signal is detected. The blur correction signal ω is output.

The high pass filter 310 includes a signal branch point 308, a reference value calculation unit 312, and a subtracter 314. The camera shake signal ω <b> 1 input to the high-pass filter 310 is branched at the signal branch point 308, one is input to the subtractor 314, and the other is input to the reference value calculation unit 312. Here, when the cut-off frequency of the high-pass filter 310 is fc ₁ , the time constant τ = 1 / (2πfc ₁ ).

The reference value calculation unit 312 is configured with a low-pass filter. Here, the cutoff frequency of the low-pass filter when the fc _2, a time constant _{τ = 1 / (2πfc 2)} . This low-pass filter outputs to the subtractor 314 a reference value ω0 for removing an offset component consisting of a low frequency component from the camera shake signal ω1.

  The subtracter 314 subtracts the reference value ω0 from the camera shake signal ω1 and outputs a shake correction signal ω. The blur correction signal ω is integrated by the integrator 316 and becomes a target position signal corresponding to the target position of the blur correction lens group 26 (see FIG. 1). The CPU 8 outputs a target position signal obtained by integrating the shake correction signal ω to the shake correction lens group driving mechanism 28 shown in FIG. Therefore, the blur correction lens group driving mechanism 28 can drive the blur correction lens group 26 and the like based on the blur correction signal ω to correct image blur.

  Here, in the conventional blur correction apparatus, the cut-off frequency of the high-pass filter 310 needs to be sufficiently low with respect to the frequency band of vibration to be detected. For example, it is said that the frequency band of camera shake vibration when using a still camera or a video movie is dominant from about 1 Hz to 15 Hz. In this case, the cut-off frequency of the high-pass filter 310 needs to be kept low, for example, about 0.1 Hz. Therefore, the conventional blur correction device has a problem that the time constant τ of the high-pass filter tends to increase, and the time until the reference value ω0 becomes stable is increased.

  The problem of this high-pass filter will be described with reference to the waveform example shown in FIG. The waveform example shown in FIG. 4 is a waveform example in the shake correction apparatus according to the reference example of the present invention, and corresponds to the attitude of the gyro 20 from the offset voltage adjustment instruction unit 318 to the offset voltage adjustment unit 304 shown in FIG. It is an example of a waveform when it is assumed that an instruction to set an offset voltage is not input.

  In FIG. 4A, the attitude of the gyro 20 changes at the timing of time t2, and the DC component of the camera shake signal ω1 changes. Hereinafter, the reference value after the fluctuation of the DC component is assumed to be a true reference value ω0 [1]. Here, since the time constant τ of the reference value calculation unit 312 is about several seconds as described above, the reference value ω0 takes several seconds to converge to the true reference value ω0 [1]. For example, at time t3, Δω, which is the difference between the true reference value ω0 [1] and the reference value ω0, becomes the error Δω of the blur correction signal ω when correcting image blur. FIG. 4B is a diagram illustrating a state in which the blur correction signal ω is converged to a true value having only the blur component after the influence of the posture component is removed. Here, the shake signal reference value shown in FIG. 4B is an output reference value in an ideal shake correction signal ω from which an offset output has been removed from the camera shake signal ω1. Since the blur correction signal ω is the result of subtracting the reference value ω0 from the camera shake signal ω1 as described above, the error Δω directly affects the blur correction signal ω as described with reference to FIG. That is, immediately after the attitude of the gyro 20 changes, the reference value ω0 has a difference with respect to the true reference value ω0 [1], and the blur correction signal ω includes an error Δω corresponding to this difference.

  In order to solve the above problem, in the first embodiment according to the present invention, as shown in FIGS. 3 and 5, the offset voltage is adjusted using the attitude signal that is the output of the attitude detection unit 18. The procedure for adjusting the offset voltage will be described with reference to the functional block diagram of FIG.

  The posture detection unit 18 includes an acceleration sensor 501, a low-pass filter 502, an A / D converter 504, and a posture determination unit 506, and outputs a change in gyro posture to the CPU 8. The acceleration sensor 501 outputs an acceleration output of each axis of xyz. These acceleration outputs are attenuated by high-frequency components that are not related to the acceleration output by the low-pass filter 502, quantized by the A / D converter 504, and input to the attitude determination unit 506. The posture determination unit 506 determines the posture of the gyro 20 from the input acceleration output of each axis, and outputs a posture signal to the offset voltage adjustment instruction unit 508 of the CPU 8.

  Note that the posture detection unit 18 may detect at least the posture around the optical axis L shown in FIG. As a result, even when the photographer changes the posture of the camera from the vertical position to the horizontal position, correct blur correction can be performed quickly.

  The offset voltage adjustment instruction unit 508 determines an appropriate offset voltage according to the attitude of the gyro 20 determined by the attitude determination unit 506, and instructs the offset voltage adjustment unit 304.

  FIG. 6 is a waveform diagram showing that the influence of the gyro attitude difference is improved by adjusting the offset voltage of the gyro described in FIGS. 3 and 5. The waveform example shown in FIG. 6 is a waveform example in the shake correction apparatus according to the first embodiment, and the offset voltage adjustment unit 304 shown in FIG. 3 is offset from the offset voltage adjustment instruction unit 318 by the offset corresponding to the gyro 20 attitude. It is an example of a waveform when the instruction | indication which sets a voltage is input.

  Specifically, FIG. 6A shows how the camera shake signal ω1 and the reference value ω0 change according to an instruction for adjusting the offset voltage from the offset voltage adjustment instruction unit 508 shown in FIG. In FIG. 6A, since the attitude of the gyro 20 (FIG. 5) changes at time t4, the output of the gyro 20 changes and the DC component of the camera shake signal ω1 fluctuates. At time t5, the offset voltage adjustment unit 304 adjusts the offset voltage in accordance with an instruction from the offset voltage adjustment instruction unit 508 (FIG. 5), thereby removing the fluctuation component of the DC component from the camera shake signal ω1. ing.

  Here, from time t4 to time t5, the offset voltage adjustment instruction unit 508 shown in FIG. 5 determines the offset voltage from the attitude signal output from the attitude detection unit 18, and changes the offset voltage to the offset voltage adjustment unit 304. I have an instruction to do. The reference value ω0 converges with a time constant τ from time t4 to time t5 toward the true reference value ω0 [2] from time t4 to time t5. Further, after time t5, it converges with a time constant τ toward the true reference value ω0 [3] after adjustment of the offset voltage.

  FIG. 6B shows that the error of the shake correction signal ω is improved by the offset voltage adjustment instruction. Here, the shake correction signal ω indicates a shake correction signal when the offset voltage adjustment is performed in the offset voltage adjustment unit 304 in accordance with an instruction from the offset voltage adjustment instruction unit 508 shown in FIG. Indicates a signal for which an offset voltage adjustment based on an instruction from the offset voltage adjustment instruction unit 508 is not performed. Here, the error Δω indicates an error when the offset voltage adjustment is performed, and the comparison error Δωref1 indicates an error when the offset voltage adjustment is not performed. It is clear that the error Δω is significantly smaller than the comparison error Δωref1 at time t6 when the adjustment of the offset voltage is completed. Therefore, it can be said that the error of the shake correction signal ω can be significantly improved by adjusting the offset voltage of the gyro.

Second Embodiment FIG. 7 is a functional block diagram for explaining blur correction control by the blur correction apparatus according to the second embodiment of the present invention. In the shake correction apparatus of the second embodiment, the output destination of the attitude signal output by the attitude detection unit 18 and the content of control using the attitude signal are different from those of the shake correction apparatus shown in FIGS. 3 and 5. . Specifically, the reference value calculation unit 312a that constitutes the high-pass filter 310a of the CPU 8a changes the time constant τ when calculating the reference value ω0 in accordance with the posture signal from the posture detection unit 18, thereby causing blurring. The error with respect to the true value of the correction signal ω is reduced. Here, since the operation of the posture detection unit 18 is the same as the operation in the first embodiment, the description thereof is omitted. In the description of the second embodiment, the description of the same parts as those in the first embodiment is omitted.

The time constant change instruction unit 708 receives the posture signal from the posture detection unit 18 and temporarily changes the time constant τ of the reference value calculation unit 312a. Here, the change of the time constant τ is changed so that the response of the reference value ω0 calculated by the reference value calculation unit 312a is improved with respect to the change of the DC component of the camera shake signal ω1. At this time, it is preferable that the time constant change instruction unit 708 controls the time constant τ = 1 / (2πfc ₂ ) to be small so that the response of the reference value ω0 is improved. That is, it is preferable that the time constant change instruction unit 708 performs control so as to increase the cutoff frequency fc ₂ = 1 / (2πτ) of the reference value calculation unit 312a. Thereafter, when the fixed time has elapsed and the value of the reference value ω0 converges to the true reference value, the time constant change instruction unit 708 returns the time constant τ to the original time constant.

  FIG. 8 is a waveform showing that the influence of the gyro attitude difference is improved by changing the time constant τ when calculating the reference value ω0 in the shake correction apparatus according to the second embodiment shown in FIG. FIG. Specifically, FIG. 8A is a diagram illustrating a state in which the response to the change in the camera shake signal ω1 is different between the reference value ω0 and the comparison reference value ω0ref2 having different time constants τ. The reference value ω0 is an example of a waveform output from the reference value calculation unit 312a in the shake correction apparatus according to the second embodiment. The reference value ω0 is a waveform example according to this embodiment in which the reference value calculation unit 312a illustrated in FIG. 7 changes the time constant τ based on an instruction from the time constant change instruction unit 708. On the other hand, the comparison reference value ω0ref2 is an example of a waveform in the shake correction apparatus according to the second reference example of the present invention, and the reference value calculation unit 312a shown in FIG. It is an example of a waveform when it is assumed that an instruction to change the value is not input.

  In FIG. 8A, at the timing of time t7, the attitude of the gyro 20 shown in FIG. 7 changes, the output of the gyro 20 changes, and the DC component of the camera shake signal ω1 changes. At time t7, the time constant change instruction unit 708 shown in FIG. 7 receives the posture signal from the posture detection unit 18, and the reference value calculation unit 312a has a better response with the time constant τ as the reference value ω0. An instruction to change is output. At this time, the reference value ω0 with the changed frequency characteristic (time constant) has a better response to the comparison reference value ω0ref2 without changing the frequency characteristic, so the true reference value ω0 is much shorter in time than ω0ref2. Converged to [4].

  FIG. 8B shows how the shake correction signal ω and the comparative shake correction signal ωref2 are converged to a state having only the shake component after the influence of the posture component is removed. Here, the blur correction signal ω is a result of subtracting the reference value ω0 from the camera shake signal ω1 as described above. The comparison blur correction signal ωref2 is also the result of subtracting the comparison reference value ω0ref2 from the blur correction signal ω1 in the same manner as the blur correction signal ω. Similar to the reference value ω0 described in the description of FIG. 8A, the blur correction signal ω of the present embodiment in which the frequency characteristic is changed has a much better response, and therefore the influence of the posture component in a much shorter time. It can be seen that has converged to a state having only the blur component. Therefore, it can be said that the error of the shake correction signal ω can be significantly improved by changing the time constant τ of the reference value ω0.

In this embodiment, when the attitude of the gyro 20 changes, control is performed so that the time constant τ = 1 / (2πfc ₂ ) of the reference value calculation unit 312a constituting the high-pass filter 310a is reduced, thereby correcting blur. It is preferable to improve the response of the signal ω. However, in the present embodiment, the high-pass filter 310a is not limited to the configuration having the low-pass filter like the reference value calculation unit 312a, and may have another configuration. For example, the high-pass filter 310a may be controlled so as to receive a posture signal from the posture detection unit 18 and to improve the response to a change in posture component of the camera shake signal ω1, and to quickly reduce the influence of the posture component. .

  In addition, this invention is not limited to embodiment mentioned above.

  For example, the movable optical component for correcting image blur may be a light transmitting member that transmits light such as a lens. Alternatively, the movable optical member may be a light reflecting member that reflects light such as a mirror. Alternatively, the movable optical member may be an image sensor such as a CCD or a CMOS.

  Further, for example, means for correcting image blur is not limited to moving the optical component as described above. For example, the image signal output from the image sensor may be corrected by software. For example, a means for electronic image restoration using PSF (point spread function) or the like may be used.

  Further, for example, the optical device may be a still camera, a video camera, a lens barrel, a camera body, a mobile phone, or the like, or an information device such as a PC having a photographing function.

8, 8a ... arithmetic unit 10 ... imaging unit 18 ... posture detection unit 20 ... shake detection unit 26 ... optical system 28 ... drive unit 101 ... cameras 312, 312a ... Reference value calculation unit 501 ... Gyro 506 ... Attitude determination unit

Claims (9)

A blur detection unit that outputs a detection signal including a blur component corresponding to blur and a posture component corresponding to posture;
An attitude detection unit that detects an attitude of the blur detection unit and outputs an attitude signal;
A calculation unit that calculates a shake correction signal for correcting shake using the detection signal and the posture signal;
And a drive unit that drives to correct the shake based on the shake correction signal. The blur correction device according to claim 1,
The shake correction apparatus, wherein the calculation unit calculates the shake correction signal using the detection signal and the posture signal so that the influence of the posture component of the detection signal is reduced. The blur correction device according to claim 1 or 2,
When the posture of the shake detection unit changes, the calculation unit reduces the detection signal so as to cancel the change in the posture component accompanying the change in posture of the shake detection unit. . The blur correction device according to any one of claims 1 to 3, wherein
The calculation unit includes a reference value calculation unit that calculates a reference value including a low frequency component of the detection signal, and calculates the blur correction signal using a difference between the detection signal and the reference value. Shake correction device. The blur correction device according to claim 4,
The blur correction device, wherein the arithmetic unit reduces the time constant of the reference value when the attitude of the blur detection unit changes. The blur correction device according to any one of claims 1 to 5, wherein
The posture detection unit includes an acceleration sensor that detects acceleration of the shake detection unit, and a posture determination unit that determines the posture of the shake detection unit based on an output signal of the acceleration sensor and outputs the posture signal. A blur correction device characterized by the above. The blur correction device according to any one of claims 1 to 6, wherein
The posture correcting unit detects a posture around an axis in a direction intersecting a direction of the blur component. The blur correction device according to any one of claims 1 to 7, wherein
The drive unit has an optical member for correcting image blur,
The blur correction device, wherein the optical member is at least one of an optical system that transmits light and an imaging unit that captures an image of light. An optical apparatus comprising the blur correction device according to claim 1.

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