JP2023037815A - Control device, imaging device, control method, and program - Google Patents

Abstract

To provide an imaging device capable of performing smooth PT drive with small angle of view fluctuations.SOLUTION: A control device (100) for controlling drive means for driving an imaging optical system in each of a pan direction and a tilt direction includes: designation means (119) for designating angular velocity in each of the pan direction and the tilt direction; acquisition means (122) for acquiring actual angular velocity in each of the pan direction and the tilt direction; and shift means (105) for shifting an angle of view. The shift means performs correction so as to reduce angular velocity difference between the angular velocity designated by the designation means and actual angular velocity acquired by the acquisition means.SELECTED DRAWING: Figure 1

Description

The present invention relates to an imaging device.

In recent years, in video production, not only handheld video cameras but also cameras with pan, tilt, and zoom functions (PTZ cameras) have been used to remotely operate and shoot images. In video production, smooth PT driving is required because quality is also required for video when changing the angle of view during panning and tilting (PT). Therefore, PTZ cameras for video production are also required to have the same quality.

However, depending on the motor and mechanical configuration used in the PTZ camera, speed unevenness occurs due to mechanical resonance and individual variation in motors. When the speed unevenness occurs, the change in the angle of view is not constant, resulting in deterioration of image quality.

Japanese Unexamined Patent Application Publication No. 2002-100000 discloses an imaging apparatus that calculates the moving speed of an object using two blur detection means and corrects the blur of the object using a shift lens. Japanese Unexamined Patent Application Publication No. 2002-200000 discloses an imaging device that corrects blurring detected by an acceleration sensor using a PT mechanism.

JP 2007-139952 A JP-A-2003-75716

Japanese Patent Laid-Open No. 2002-200001 does not mention the case of performing PT driving with a motor. Further, with the configuration of Patent Document 1, blurring cannot be corrected when the subject does not exist within the screen. The image pickup apparatus disclosed in Patent Document 2 cannot cope with blur caused by the PT mechanism. For this reason, neither Patent Document 1 nor Patent Document 2 can reduce the change in the angle of view during PT driving. , a control method, and a program.

A control device as one aspect of the present invention is a control device that controls driving means for driving an imaging optical system in each of the pan direction and the tilt direction, and designates angular velocities in each of the pan direction and the tilt direction. specifying means; acquisition means for acquiring actual angular velocities in each of the panning direction and the tilting direction; and shift means for shifting an angle of view, wherein the shifting means is the angular velocity specified by the specifying means. Correction is performed so as to reduce the angular velocity difference from the actual angular velocity acquired by the acquiring means.

Other objects and features of the invention are described in the following embodiments.

According to the present invention, it is possible to provide a control device, an imaging device, a control method, and a program capable of smooth PT driving with a small change in angle of view.

1 is a block diagram of an imaging device according to each embodiment; FIG. 4 is a flow chart of a control method in the first embodiment; 4 is a graph showing the relationship between time and angular velocity of the PT motor in the first embodiment; FIG. 4 is an explanatory diagram of the position of PT at time T1 in FIG. 3; 8 is a flow chart of a control method in the second embodiment; 9 is a flow chart of a control method in the third embodiment; 10 is a flow chart of a control method in the fourth embodiment; It is a threshold table of specified angular velocity in the fourth embodiment. It is a threshold table of the difference between the specified angular velocity and the actual angular velocity in the fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(overall structure)
First, with reference to FIG. 1, an imaging device according to each embodiment will be described. FIG. 1 is a block diagram of an imaging device (control device) 100. As shown in FIG. The angular velocity sensor 101 acquires the vibration generated in the imaging device 100 as an angular velocity signal. The AD converter 102 converts the angular velocity signal from the angular velocity sensor 101 into a digital signal and outputs the digital signal. The filter processing unit 103 filters the digital signal output from the AD conversion unit 102 in a predetermined frequency band using an HPF (high pass filter) or LPF (low pass filter). The integration processing unit 104 integrates the signal output from the filter processing unit 103 and calculates the blur amount.

A correction amount calculation unit 105 calculates a correction amount based on the blur amount calculated by the integration processing unit 104 . The correction amount calculated by the correction amount calculation unit 105 is output to the motor driving unit of each anti-vibration mechanism. In the case of optical image stabilization, the correction amount calculation unit 105 outputs the correction amount to the lens motor driving unit (driving means) 106 . A lens motor driving unit 106 drives a lens motor 107 . By driving the lens motor 107, the shift lens 108 of the optical vibration reduction mechanism moves in the direction perpendicular to the optical axis (the direction intersecting the optical axis), and the light flux becomes appropriate for the optical axis. Shake is corrected. On the other hand, in the case of image sensor stabilization, the correction amount calculation unit 105 outputs the correction amount to the image sensor motor driving unit (driving means) 109 . An imaging device motor driving unit 109 drives an imaging device motor 110 . By driving the image pickup device motor 110, the image pickup device 111 moves in the direction perpendicular to the optical axis, and the luminous flux becomes appropriate with respect to the optical axis, thereby correcting blurring. In each embodiment, the shift means for shifting the angle of view is composed of, for example, a correction amount calculator 105, a lens motor driver 106, a lens motor 107, an image sensor motor driver 109, and an image sensor motor 110. FIG.

Light that has passed through an imaging optical system composed of the shift lens 108 and other lens groups is condensed on the imaging element 111 . Other lens groups include a focus lens for focusing on a subject, a zoom lens for adjusting the angle of view, and the like. Light that has entered through the imaging optical system passes through an optical filter 112 such as an infrared cut filter and enters an imaging device 111 .

The video imaged by the imaging device 111 is subjected to luminance adjustment of the video signal and output as an analog imaging signal. The AD converter 113 converts the analog imaging signal output from the imaging element 111 into a digital signal. A video signal processing unit 114 performs predetermined processing on the digital imaging signal from the AD conversion unit 113 and outputs a luminance signal and a color signal for each pixel. That is, the image signal processing unit 114 creates an image for output and also creates each parameter used for controlling aperture and focusing.

The motion vector detection unit 115 uses the video signal from the video signal processing unit 114 to detect the amount of motion vector by taking the difference from the previous frame. The filtering unit 116 filters the motion vector detected by the motion vector detecting unit 115 in a predetermined frequency band. The integration processing unit 117 integrates the filtered motion vector amount to calculate the blur amount. The focal length calculation unit 118 adjusts the blur amount calculated by the integration processing unit 117 to a blur amount according to the focal length. A correction amount calculation unit 105 calculates a correction amount based on the blur amount calculated by the focal length calculation unit 118 . The correction amount calculated by the correction amount calculation unit 105 is output to the motor control unit of each anti-vibration mechanism, and correction is performed.

The PT motor control section 119 outputs a control signal to the PT motor drive section 120 for performing PT drive (pan drive and tilt drive). The PT motor drive section 120 drives the PT motor 121 based on the control signal from the PT motor control section 119 . By driving the PT motor 121, the imaging optical system including the lens and sensor moves in the PT direction (pan direction and tilt direction). The PT motor speed acquisition unit 122 measures and acquires the actual speed (actual angular speed) of the PT motor 121 .

It should be noted that the control device that controls the driving means for driving the imaging optical system in each of the pan direction and tilt direction is not limited to a configuration integrated with the imaging apparatus 100 including the imaging optical system, and the imaging optical system, etc. It may be configured as a separate body.

(First embodiment)
Next, with reference to FIG. 2, a correction method (control method) for image field angle fluctuation due to speed unevenness (PT speed unevenness) in the first embodiment will be described. FIG. 2 is a flow chart of the control method in this embodiment. Originally, both PT drive (pan drive and tilt drive) should be explained, but for the sake of simplification, only pan drive will be explained. This point is the same for each embodiment described later.

First, in step S201, the PT motor control section (designating means) 119 designates an angular velocity (an angular velocity of Pan) to the PT motor driving section 120, and outputs a drive command (control signal). Subsequently, in step S202, the PT motor driving section 120 starts driving the PT motor 121 so that the angular velocity specified by the PT motor control section 119 is achieved. The PT motor 121 is a stepping motor (STM), an ultrasonic motor (USM), or the like, but is not limited thereto.

At this time, the PT motor driving unit 120 controls the PT motor 121 so as to achieve the specified angular velocity. However, in practice, it is difficult to always achieve the specified angular velocity, and velocity unevenness (variation in velocity) occurs. Various factors are conceivable for the speed unevenness. For example, the resonance point is generated by the PT motor 121 itself and the mechanical structure around the PT motor 121 . When the driving speed overlaps with the resonance point, unnecessary vibration occurs, the actual angular speed deviates from each specified speed, and speed unevenness occurs. Also, in the STM, if the number of magnetic poles of the motor and the stopping resolution are low, speed unevenness occurs. Also, when the distance between the magnetic poles is not constant, the speed unevenness occurs. Further, in USM, since feedback control is performed, speed unevenness occurs in terms of control. By applying a strong feedback, the speed unevenness is reduced, but there is a demerit that resonance is more likely to occur. If speed unevenness occurs as described above, it also affects the image.

FIG. 3 is a graph showing the relationship between time and angular velocity of the PT motor 121. As shown in FIG. In FIG. 3, the horizontal axis indicates time (sec) and the vertical axis indicates angular velocity (deg/sec). FIG. 4 is an explanatory diagram of the position of PT at time T1 in FIG. As shown in FIG. 3, for control purposes, the PT motor 121 is to be driven by designating a set speed of 1 deg/sec indicated by the broken line, but in reality, speed irregularities occur as shown by the actual speed indicated by the solid line. Suppose The actual speed at the position of time T1 is 1.2 deg/sec. At this time, as shown in FIG. 4, the ideal screen center position and the actual screen center position are different. Although it is intended to be driven at a constant speed in this way, if the speed is uneven as shown in FIG.

It is difficult to take countermeasures against the speed unevenness, which occurs theoretically and mechanically. Even if it were possible to solve this problem with a mechanism, it would be necessary to add an unnecessary mechanism, which would increase costs and impair design. Therefore, in the present embodiment, instead of reducing the speed unevenness, the image angle change unevenness caused by the speed unevenness is reduced by using an anti-vibration mechanism.

Subsequently, in step S203 of FIG. 2, the PT motor speed obtaining section (obtaining means) 122 detects (obtains) the actual angular speed of the pan. At this time, the absolute position sensor may be used to detect the position, and the actual angular velocity may be calculated based on the previous position and the current position, or the angular velocity sensor 101 may be used to calculate the actual angular velocity. Alternatively, the motion vector detected by the motion vector detection unit 115 may be used to calculate the actual angular velocity.

Subsequently, in step S204, the correction amount calculator 105 calculates the difference (angular velocity difference) between the actual angular velocity and the specified angular velocity (set velocity). Subsequently, in step S205, the shift means including the correction amount calculation unit 105 corrects the difference calculated in step S204 by the anti-vibration mechanism (performs correction so as to reduce the angular velocity difference between the designated angular velocity and the actual angular velocity). That is, the shift means calculates a correction amount based on the difference, and controls each motor driving section to drive the anti-vibration mechanism. Here, the anti-vibration mechanism may be an optical anti-vibration mechanism using the shift lens 108, an image sensor anti-vibration mechanism using the image sensor 111, or both anti-vibration mechanisms. When using the image pickup device image stabilizing mechanism, the image pickup device 111 itself may be shifted or corrected, or the clipping position may be changed for correction.

When correction is performed by the imaging device image stabilization mechanism, it is necessary to change the correction amount according to the focal length. For example, when the correction angle is θ and the focal length is f, the correction amount d can be expressed by the following equation (1).

Note that the calculation method of the correction amount d is an example, and other calculation methods may be used.

Subsequently, in step S206, the PT motor control unit 119 determines whether pan driving is being performed. If pan driving is in progress, the process returns to step S203 to repeat the correction. On the other hand, when the pan drive is stopped, the program for correcting the uneven change in the angle of view of the image due to the uneven PT speed ends.

According to the present embodiment, even if the PT velocity unevenness occurs and the angle of view deviates from the original angle of view due to the uneven speed, the angle of view can be shifted by an anti-vibration mechanism such as a shift lens. Thus, it becomes possible to correct the angle of view to the original position. As a result, although the PT speed unevenness occurs, the view angle unevenness caused by the speed unevenness can be corrected, so it is possible to provide the user with a smooth image during the PT with less view angle change unevenness.

(Second embodiment)
Next, with reference to FIG. 5, a correction method (control method) for image field angle fluctuation due to speed unevenness (PT speed unevenness) in the second embodiment will be described. FIG. 5 is a flow chart of the control method in this embodiment. In this embodiment, a method of selecting a correcting means (anti-vibration mechanism) according to the amount of speed unevenness will be described. In this embodiment, steps S505 to S509 are different from the first embodiment. Steps S501 to S504 and S510 are the same as steps S201 to S204 and S206 of the first embodiment, respectively, so description thereof will be omitted.

In the first embodiment, two types of correction means (vibration reduction mechanism), that is, optical vibration reduction and image pickup device vibration reduction, are described. For optical vibration reduction, the permissible correction angle is constant and does not depend on the focal length. On the other hand, for image pickup element stabilization, the permissible correction angle is determined based on the limit driving amount of the image pickup element 111 and the focal length. Assuming that the limit driving amount of the image sensor 111 is d and the focal length is f, the allowable correction angle θ can be expressed by the following equation (2).

When the focal length f is long, the permissible correction angle θ becomes narrow. On the other hand, when the focal length f is short, the permissible correction angle θ becomes wide. Note that the calculation method of the allowable correction angle θ is an example, and other calculation methods may be used.

In step S505 of FIG. 5, the correction amount calculation unit 105 determines whether or not the difference angular velocity (correction angle) calculated in step S504 is within the correction range of optical image stabilization. If the correction angle is within the correction range, the process proceeds to step S506. On the other hand, if the correction angle is not within the correction range (if the correction angle exceeds the correction range), the process proceeds to step S507.

In step S<b>506 , the imaging apparatus 100 performs optical image stabilization, that is, correction using the shift lens 108 . In step S<b>507 , the correction amount calculation unit 105 determines whether the difference angular velocity (correction angle) calculated in step S<b>504 is within the correction range for image stabilization. If the correction angle is within the correction range, the process proceeds to step S508. On the other hand, if the correction angle is not within the correction range (if the correction angle exceeds the correction range), the process proceeds to step S509. It should be noted that the correction range for the image pickup element stabilization in step S507 may be calculated sequentially based on the focal length and the drive range of the image pickup element 111 . In step S<b>508 , the imaging apparatus 100 performs image sensor stabilization, that is, correction using the image sensor 111 . In step S<b>509 , the imaging apparatus 100 performs correction using both optical image stabilization and image sensor image stabilization, that is, both the shift lens 108 and image sensor 111 .

According to the present embodiment, in an imaging apparatus having both an optical image stabilizing mechanism and an image sensor image stabilizing mechanism, the image stabilizing mechanism to be used for correction can be selected according to the focal length of the imaging optical system. Therefore, even if the angle required for correction of the change in the angle of view exceeds the permissible correction angle for optical vibration reduction, correction can be made by the imaging device vibration reduction mechanism.

(Third embodiment)
Next, with reference to FIG. 6, a correction method (control method) for image angle change unevenness due to speed unevenness (PT speed unevenness) in the third embodiment will be described. FIG. 6 is a flow chart of the control method in this embodiment. In this embodiment, a method of selecting means for calculating the actual angular velocity of PT in the imaging environment will be described. In this embodiment, steps S603 to S605 are different from the first embodiment. Steps S601, S602, and S606-S608 are common to steps S201, S202, and S204-S206 of the first embodiment, respectively, so description thereof will be omitted.

In the first embodiment, the absolute value sensor, the angular velocity sensor, and the motion vector have been described as means for calculating the actual angular velocity of the PT. The accuracy of the actual angular velocity detection calculated by the absolute value sensor is good, but there is a possibility that the absolute value sensor is not attached, and it is costly to add it for correction. The angular velocity sensor is mounted on the anti-vibration mechanism. However, angular velocity sensors are prone to noise, and minute angular velocities are prone to errors. In addition, since the motion vector is obtained from the video, if the video is running or there is a lot of noise when using a slow shutter speed, it will be difficult to obtain the feature points, resulting in a decrease in the accuracy of the angular velocity. Therefore, in this embodiment, the means for detecting the actual angular velocity of the PT is selected according to the shooting environment.

In step S603, the correction amount calculation unit 105 determines whether the shutter speed is equal to or higher than the threshold. If the shutter speed is equal to or greater than the threshold, the process proceeds to step S604. On the other hand, if the shutter speed is slower than the threshold, the process proceeds to step S605. Note that in the present embodiment, the shutter speed condition is used in the determination in step S603, but instead of this, other shooting conditions such as image gain related to noise may be used.

In step S<b>604 , the correction amount calculation unit 105 calculates the actual angular velocity based on the motion vector acquired by the motion vector detection unit 115 . In step S<b>605 , the correction amount calculator 105 calculates the actual angular velocity based on the signal acquired by the angular velocity sensor 101 .

According to this embodiment, the real angular velocity can be calculated with high accuracy by selecting (changing) the means for detecting the real angular velocity of the PT according to the imaging conditions. As a result, it is possible to highly accurately correct the uneven change in the angle of view due to the uneven speed of the PT.

(Fourth embodiment)
Next, with reference to FIG. 7, a correction method (control method) for image angle change unevenness due to speed unevenness (PT speed unevenness) in the fourth embodiment will be described. FIG. 7 is a flow chart of the control method in this embodiment. In the present embodiment, a method for determining whether or not to correct unevenness in the angle of view of an image due to unevenness in PT speed will be described. In this embodiment, steps S703 to S707 are different from the first embodiment. Since steps S701, S702, and S708 are common to steps S201, S202, and S206 of the first embodiment, respectively, description thereof will be omitted.

In the first embodiment, a simple example of implementing a method for correcting unevenness in image angle change caused by PT speed unevenness has been described. However, in actuality, when the PT drive is too fast, when the change in the angle of view is too large and the user does not know whether the change in the angle of view is smooth, or when the angular velocity to be corrected is too small and the user cannot distinguish even if the correction is made. There is If the angular velocity to be corrected is erroneously detected or overcorrected, it is uncomfortable for the user, so it is preferable not to correct it.

In step S703, the correction amount calculation unit 105 determines whether or not the specified angular velocity (set angular velocity) for pan driving is equal to or less than a threshold. FIG. 8 is a threshold table for specified angular velocities, showing the relationship between the focal length (mm) and the threshold (deg/sec). The threshold obtained by referring to the table shown in FIG. 8 can be used for the determination in step S703. That is, the threshold changes based on the focal length of the imaging optical system. Note that FIG. 8 is merely an example, and the threshold may be set using another method. If the designated angular velocity is equal to or less than the threshold, the process proceeds to step S704. On the other hand, if the designated angular velocity exceeds the threshold, the process proceeds to step S708.

In step S704, the PT motor speed obtaining unit 122 detects (obtains) the actual angular speed of the pan. Subsequently, in step S705, the correction amount calculator 105 calculates the difference between the actual angular velocity and the designated angular velocity. Subsequently, in step S706, the correction amount calculation unit 105 determines whether or not the difference angular velocity calculated in step S705 is equal to or less than a threshold. FIG. 9 is a threshold table for the difference between the designated angular velocity and the actual angular velocity, showing the relationship between the focal length (mm) and the threshold (deg/sec). The threshold obtained by referring to the table shown in FIG. 9 can be used for the determination in step S706. That is, the threshold changes based on the focal length of the imaging optical system. Note that FIG. 9 is merely an example, and the threshold may be set using another method. If the differential angular velocity is equal to or less than the threshold, the process proceeds to step S707. On the other hand, if the differential angular velocity exceeds the threshold, the process proceeds to step S708. In step S707, the imaging apparatus 100 corrects the difference using the vibration reduction mechanism (shift lens 108).

According to this embodiment, the necessity of correction control is determined based on the specified angular velocity or the difference between the specified angular velocity and the actual angular velocity (angular velocity difference). That is, the shift means does not perform correction when the designated angular velocity or the angular velocity difference is greater than the threshold. As a result, it is possible to prevent deterioration of the image quality during the PT due to excessive correction when the actual angular velocity is erroneously detected under the condition that the correction effect is small.

(Other examples)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

In each embodiment, the change in the angle of view of the image due to the uneven speed of the motor for PT driving is corrected using the shift lens or the shift function of the imaging device. Therefore, according to each embodiment, it is possible to provide a control device, an imaging device, a control method, and a program capable of smooth PT driving with a small change in angle of view.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

100 imaging device (control device)
105 correction amount calculator (shift means)
119 PT motor control unit (designation means)
122 PT motor speed acquisition unit (acquisition means)

Claims (11)

A control device for controlling driving means for driving an imaging optical system in each of the pan direction and the tilt direction,
designating means for designating angular velocities in each of the pan direction and the tilt direction;
acquisition means for acquiring actual angular velocities in each of the pan direction and the tilt direction;
and a shift means for shifting the angle of view,
The control device, wherein the shifting means performs correction so as to reduce an angular velocity difference between the angular velocity specified by the specifying means and the actual angular velocity acquired by the acquiring means. 2. The control device according to claim 1, wherein the shift means shifts the angle of view by driving at least one of a shift lens and an imaging device in a direction perpendicular to the optical axis of the imaging optical system. . 2. The shifting means shifts the angle of view by driving at least one of the shift lens and the imaging device based on the angular velocity difference and the focal length of the imaging optical system. The control device according to . 4. The control device according to any one of claims 1 to 3, wherein said acquisition means includes at least one of an absolute position sensor, an angular velocity sensor, and a motion vector detection means. 5. The control according to claim 4, wherein the acquisition means acquires the actual angular velocity using one of the absolute position sensor, the angular velocity sensor, and the motion vector detection means based on shooting conditions. Device. 6. The control device according to claim 5, wherein the photographing condition is a condition related to shutter speed. 7. The control device according to claim 1, wherein said shifting means does not perform said correction when said angular velocity or said angular velocity difference specified by said specifying means is larger than a threshold value. . 8. The control device according to claim 7, wherein said threshold varies based on the focal length of said imaging optical system. an imaging optical system;
driving means for driving the imaging optical system in pan and tilt directions;
An imaging apparatus comprising: the control apparatus according to any one of claims 1 to 8. A control method for controlling driving means for driving an imaging optical system in each of the pan direction and the tilt direction, comprising:
a specifying step of specifying an angular velocity in each of the pan direction and the tilt direction;
an obtaining step of obtaining an actual angular velocity in each of the pan direction and the tilt direction;
and a shift step for shifting the angle of view,
The control method, wherein in the shift step, correction is performed so as to reduce an angular velocity difference between the angular velocity specified in the specifying step and the actual angular velocity acquired in the acquiring step. A program that causes a computer to execute the control method according to claim 10 .

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