Image shake arrester and camera system

0001The present invention relates to an image shake prevention device and a camera system, and more particularly to an image shake prevention device and a camera system that prevent image shake of an imaging camera capable of pan-tilt operation.

0002A camera system for surveillance using a so-called PTZ camera (hereinafter, also simply referred to as a camera) capable of remotely controlling pan operation, tilt operation, and zoom operation is known. A motor is used as a drive source for each operation. In particular, DD (direct drive) motors capable of high-speed response and high-precision positioning are often used as motors for pan operation and tilt operation.

0003In a camera system, if the camera is installed in an outdoor steel tower or the like, image shake occurs when the camera is shaken by the wind. Further, if it is installed along a main road or in the vicinity of mechanical equipment, vibration is constantly applied due to the running of a vehicle or the operation of a machine, and steady image shaking occurs. These image shakes have become noticeably recognized in recent years due to the high magnification of the zoom lens, and when the image shakes are large, they may hinder the monitoring work.

0004Therefore, various devices for preventing image shake have been proposed. In Patent Document 1, a sensor is provided in a camera to detect the shaking of the camera, and an optical correction that moves a lens or an image sensor so as to correct the detected shaking, or an electron that moves an image cutout position from the image sensor. It is described that the expression correction is performed to correct the shaking of the image.

<p num="0005"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2009-139827</text></patcit></p>

<p num="0006"> By the way, in recent years, a CMOS sensor has come to be used as an image sensor instead of a CCD sensor. Since the CMOS sensor uses a rolling shutter system, if image shake is corrected by electronic correction that moves the image cutout position from the image sensor, image distortion occurs depending on the operating conditions, making it difficult to obtain a good image.</p><p num="0007"> On the other hand, when correction is performed by optical correction that moves the lens or the image sensor, the position and angle of the light flux that reaches the image sensor through the lens changes. Therefore, a region other than the central region where the characteristics of the lens are the best is frequently used, and it is difficult to obtain a good image with high image quality. Further, since the amount of movement of the lens or the image sensor cannot be increased, sufficient correction cannot be made when the shaking is large, and it is difficult to obtain a good image. In addition, a space for arranging the drive mechanism is required in the lens, which limits the miniaturization of the camera. In addition, power consumption increases due to the operation of the drive mechanism, and if the camera is systematized with PoE (Power over Ethernet) (registered trademark), the margin of power decreases and it is difficult to systematize PoE. Problems occur regardless of the type of image sensor.</p><p num="0008"> Therefore, the problem to be solved by the present invention is that a good image in which image blurring is prevented can be obtained regardless of the type of the image sensor, and image blurring facilitates miniaturization of the camera and systematization using PoE. The purpose is to provide prevention devices and camera systems.</p>

<p num="0009"> In order to solve the above problems, the present invention has the following configuration. 1) The first motor (Mp) that pans the camera (CM) and A second motor (Mt) that tilts the camera unit (CM), The accelerometer (9) attached to the camera unit (CM) and When acceleration is generated in the camera unit (CM) while the pan operation and the tilt operation are not executed, the camera unit (SN2) is output from the acceleration sensor (9). A control unit (20) that controls the operation of the first motor (Mp) and the second motor (Mt) so as to reduce the acceleration generated in the CM). It is an image shake prevention device (GB) having. 2) A camera unit (CM), a first motor (Mp) that pans the camera unit (CM), a second motor (Mt) that tilts the camera unit (CM), and the camera unit. A camera (1) with an accelerometer (9) attached to (CM), A control device (20) connected to the camera (1) and controlling the operation of the first motor (Mp) and the second motor (Mt). Consists of When the camera unit (CM) is accelerated while the control device (20) is not performing the pan operation and the tilt operation, the sensor signal (SN2) output from the acceleration sensor (9) is generated. ) Is a camera system (51) that controls the operation of the first motor (Mp) and the second motor (Mt) so as to reduce the acceleration generated in the camera unit (CM).</p>

<p num="0010"> According to the present invention, regardless of the type of the image sensor, a good image in which image blurring is prevented can be obtained, and the effect of miniaturizing the camera and facilitating systematization using PoE can be obtained.</p>

0011<figref num="1">It is a whole system diagram for demonstrating the camera system 51 of the Example of the camera system which concerns on embodiment of this invention.</figref><figref num="2">It is a perspective view for demonstrating the camera 1 used in the camera system 51.</figref><figref num="3">It is a block diagram for demonstrating the image shake prevention device GB which is an Example of the image shake prevention device which concerns on embodiment of this invention.</figref><figref num="4">It is a figure for demonstrating the shaking of the camera part CM provided in the camera 1.</figref><figref num="5">It is another block diagram for explaining the image shake prevention device GB.</figref>

0012The image shake prevention device and the camera system according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5 by preferred embodiments.

0013An embodiment to be described is a camera system 51 for surveillance. As shown in FIG. 1, the camera system 51 includes a camera 1 which is a PTZ camera mounted on the dome camera DC, and a control device 20 connected to the camera 1 by wire or wirelessly. There is. The pan operation, tilt operation, and zoom operation of the camera 1 are controlled by the control device 20. The control status of the monitoring operation and the images (including moving images and still images) taken by the camera 1 are displayed on the image display device 30 connected to the control device 20. Further, the operation and processing instructions are input by the operator via the input device 31 connected to the control device 20.

0014The control device 20 includes a calculation unit 21, a motor drive unit 26, a pan / tilt motion analysis unit 27, and a storage unit MR. Further, in the camera system 51, the image shake prevention device GB is configured by the acceleration sensor 9, the calculation unit 21, the motor drive unit 26, the pan / tilt motion analysis unit 27, the storage unit MR, and the motor Mp and the motor Mt.

0015FIG. 2 is an external perspective view for explaining the camera 1. For the sake of explanation, the directions of the arrows shown in FIG. 2 are defined as the directions of up, down, left, right, front and back.

0016The camera 1 includes a main body 3 having an image pickup lens 2 and an image sensor S that converts the image formation of the image pickup lens 2 into an electric signal, a pair of support brackets 4 connected to the left and right sides of the main body 3, and a main body. It has a pair of base frames 5 which are connected to 3 and a support bracket 4 on both the upper and lower sides to form a part of a spherical shell. The base frame 5 is a member that also functions as a heat sink, and has a spherical shell shape with irregularities in order to obtain a large surface area. That is, the image pickup lens 2, the main body 3, the pair of support brackets 4, and the pair of base frames 5 are integrated as a camera unit CM. The signal from the image sensor S is output from the camera unit CM as an image signal SN1 (see FIG. 1) and sent to the control device 20.

0017The camera unit CM is rotatably supported around the axis CL1 by a pair of support plates 6 arranged on the left and right. This rotation is performed by driving the motor Mt, which is a DD motor attached to one of the support plates 6. The pair of support plates 6 are connected to the top plate 7 above. The top plate 7 is connected to the output shaft (rotor side) of the motor Mp. The housing (stator side) of this motor Mp is fixed to the mounting plate 8 on the dome camera DC side. That is, the camera unit CM is rotatably supported on the top plate 7 around the axis CL2. This rotation is performed by driving the motor Mp, which is a DD motor. The drive of the motor Mt and the motor Mp is controlled by the control device 20.

0018The camera unit CM is provided with a three-axis acceleration sensor 9. The acceleration sensor 9 detects accelerations in three directions orthogonal to each other including the direction of gravity, and outputs the sensor signal SN2 (see FIG. 1). The sensor signal SN2 is sent from the camera unit CM to the image signal control device 20.

0019With the above configuration, the camera 1 is mounted on the dome camera DC, and the pan operation (see arrow DR1) is executed by driving the motor Mp, and the tilt operation (see arrow DR2) is executed by driving the motor Mt. To. Further, the image signal SN1 and the sensor signal SN2 are sent from the dome camera DC to the control device 20.

0020Next, when an external force is applied to the installed dome camera DC and the camera unit CM shakes, the control by the image shake prevention device GB will be described mainly with reference to FIGS. 3 to 5. .. The calculation unit 21 of the image shake prevention device GB includes a pre-processing unit 22, a shake analysis unit 23, a correction signal generation unit 24, a post-processing unit 25, and a pan-tilt motion analysis unit 27 (see FIG. 5). First, a case where the camera unit CM shakes when the pan / tilt operation is not executed will be described.

0021When a force due to wind pressure is applied to a support member such as the dome camera DC or a support column that supports the dome camera DC, the support member sways together with the dome camera DC. The start of this shaking is included in the sensor signal SN2 as a change in the acceleration component of the three axes by the acceleration sensor 9 provided in the camera unit CM, and is sent to the control device 20.

0022The sensor signal SN2 that has entered the control device 20 is processed by the calculation unit 21. In the calculation unit 21, the preprocessing unit 22 performs processing such as amplification, filtering, and A / D conversion, and sends the data to the shaking analysis unit 23.

0023The shaking analysis unit 23 constantly monitors the sensor signal SN2 from the acceleration sensor 9. When the occurrence of acceleration is detected in this monitoring, the detection content is set as acceleration information α1, and from the acceleration information α1, the sway acceleration component Yp in the direction orthogonal to the axis CL2 (pan direction) and the direction orthogonal to the axis CL1 ( The sway acceleration component Yt in the tilt direction) is obtained. The shaking acceleration components Yp and Yt are components of the pan direction and the tilt direction of the acceleration that causes the shaking in the camera unit CM.

0024Based on the sway acceleration components Yp and Yt obtained by the sway analysis unit 23, the correction signal generation unit 24 generates offset acceleration information nα1 for executing the pan operation and the tilt operation so as to cancel the acceleration. The offset acceleration information nα1 is generated by inverting the sign of the acceleration component of the acceleration information α1 in principle. That is, the correction signal generation unit 24 inverts the signs of the fluctuation acceleration components Yp and Yt to generate the correction acceleration components -Yp and -Yt. Then, the operation signal SN3 for executing the rotation operation corresponding to the corrected acceleration component-Yp and the corrected acceleration component-Yt by the motors Mp and Mt is generated.

0025The operation signal SN3 is sent to the motor drive unit 26, which is a motor driver, after undergoing processing such as D / A conversion by the post-processing unit 25. The motor drive unit 26 drives the motors Mp and Mt by the motor drive signals SN3p and SN3t generated based on the operation signal SN3.

0026In this way, when the pan / tilt operation is not executed, the control device 20 performs a pan operation and a tilt operation that cancel out the shaking caused by the acceleration as much as possible based on the acceleration generated in the camera unit CM. Closed loop control of Mp and Mt. The rotations of the motors Mp and Mt are fed back to the control device 20 by FG signals output from an FG sensor (not shown).

0027FIG. 4 is a diagram for comparing the time lapse of the shaking of the camera unit CM when the camera 1 shakes, with or without control of the image shaking prevention device GB. The vertical axis is the amplitude of the sway, and the horizontal axis is the time t. In FIG. 4, the case where the image shake prevention device GB is not controlled is shown by the alternate long and short dash line LN1, and the case where the control is performed is shown by the solid line LN2. The same external force is applied to the camera 1.

0028As is clear from FIG. 4, the camera unit CM is almost completely eliminated by controlling the image shake prevention device GB. That is, although the dome camera DC as a whole shakes due to external vibration, the posture of the camera unit CM supported by the support bracket 4, the support plate 6, and the top plate 7 is caused by the pan operation and the tilt operation that cancel the shaking. , It is controlled so that it hardly changes from the case where there is no shaking. That is, the camera unit CM is controlled so as to always maintain the absolute posture with respect to the vertical direction.

0029Next, the sway prevention control when the sway occurs during the execution of the pan operation or the tilt operation will be described. The pan operation and tilt operation instructions are input by the operator via the input device 31. The input device 31 outputs the input instruction content as an input signal SN4 to the control device 20. The input signal SN4 that has entered the control device 20 is input to the pan / tilt motion analysis unit 27.

0030The pan / tilt motion analysis unit 27 obtains the acceleration generated in the camera unit CM when the instructed pan operation and tilt operation are executed as acceleration information α2, and supplies the acceleration information to the correction signal generation unit 24. The acceleration information α2 is information including the pan-tilt acceleration component Sp in the pan direction and the pan-tilt acceleration component St in the tilt direction in the camera unit CM.

0031The pan-tilt motion analysis unit 27 outputs acceleration information α2 to physical quantities such as the mass and moment of inertia of the moving part that operates in the pan-tilt motion including the camera section CM, and the instruction contents of the pan-tilt motion, specifically, the pan-tilt motion and the tilt motion. It is obtained from the operation amount, each operation direction, and the indicated amount such as each operation speed. Physical quantities such as the mass and moment of inertia of the moving part are stored in advance in the storage unit MR.

0032The correction signal generation unit 24 generates offset acceleration information nα1 from the acceleration information α1 generated by the vibration analysis unit 23 based on the sensor signal SN2. Next, the correction signal generation unit 24 adds up the generated offset acceleration information nα1 and the acceleration information α2 from the pan / tilt motion analysis unit 27, and the correction acceleration component Sp-Yp in the pan direction and the correction acceleration component St- in the tilt direction. Generate Yt and. Then, the operation signal SN5 for executing the rotation operation corresponding to the corrected acceleration components Sp-Yp and St-Yt by the motors Mp and Mt is generated.

0033The operation signal SN5 is sent to the motor drive unit 26, which is a motor driver, after undergoing processing such as D / A conversion by the post-processing unit 25. The motor drive unit 26 drives the motors Mp and Mt by the motor drive signals SN5p and SN5t generated based on the operation signal SN5.

0034As described above, when the pan / tilt operation is being executed, the control device 20 can shake due to the external force of the camera unit CM based on the acceleration generated in the camera unit CM and the acceleration generated in the pan / tilt operation instructed from the input device 31. The motors Mp and Mt are controlled in a closed loop so as to perform the instructed pan operation and tilt operation while canceling each other as much as possible. In other words, the control device 20 does not make a correction for offsetting or reducing the acceleration based on the pan-tilt operation instructed from the outside, and cancels it only for the acceleration caused by the shaking. Make corrections.

0035As a result, in the camera system 51, even if the camera 1 is shaken by an external force during the pan-tilt operation, the camera unit CM is not affected by the shake and is absolutely pan-tilt with reference to the vertical direction. The camera unit CM pan operation and tilt operation are independently controlled so as to execute the operation.

0036In the camera system 51, it is preferable to use DD motors capable of high-resolution and high-speed control in mSec units for the motors Mp and Mt of the camera 1. As a result, the dome camera DC can be pan-tilted by the camera unit CM so as to substantially cancel the shaking frequency (for example, several hundred Hz or less) that may occur in a normal installation state. Therefore, a better image can be obtained.

0037The shaking prevention control during execution of the pan / tilt operation is not limited to the configuration and procedure of the control device 20 described above, and can be appropriately modified. The image shake prevention device GB may be any device that at least reduces the shake of the image from the camera unit CM, and it is desirable that the image shake prevention device GB can be controlled so that the shake of the image becomes zero.

0038Since the shake prevention device and the camera system of the present invention are not electronic but move the entire camera unit CM to prevent shake, even if the image sensor S is a CMOS sensor, image distortion does not occur. Further, since the camera unit CM is moved as a whole to prevent shaking instead of the optical type, the luminous flux passes through the central region where the characteristics of the lens are the best. As a result, a good image with high image quality can be obtained. Further, since the existing structure provided for the pan-tilt operation is used for the operation of preventing the shaking, a large amount of movement can be taken. Therefore, sufficient correction can be made even when the shaking is large. Further, since the existing structure provided for the pan-tilt operation is used for the operation of preventing the shaking, a space for arranging the drive mechanism in the lens is unnecessary. This makes it easy to miniaturize the camera. Further, since the existing structure provided for the pan-tilt operation is used for the operation for preventing the shaking, the increase in power consumption is suppressed. As a result, the decrease in the power margin is suppressed to the minimum, and the PoE systemization becomes easy.

0039Examples of the present invention are not limited to the above-described configurations and procedures, and may be modified examples as long as the gist of the present invention is not deviated.

0040The acceleration sensor 9 may be attached to a member (camera unit CM) in which the pan-tilt operation is integrally performed, but it eliminates the influence of the resonance of the member and accurately determines the acceleration that affects the shaking of the acquired image. For detection, it is preferable that the image pickup lens 2 is mounted as close as possible to the optical axis CL. Specifically, it is a lens frame or the like that holds the image pickup lens 2.

00411 camera 2 Imaging lens 3 Main body 4 Support bracket 5 base frame 6 Support plate 7 Top plate 8 mounting plate 9 Accelerometer 20 Control unit 21 Arithmetic unit, 22 Preprocessing unit, 23 Shake analysis unit 24 Correction signal generator, 25 Post-processing unit, 26 Motor drive unit 27 Pan-tilt motion analysis unit 30 image display device, 31 input device, 51 camera system CL1, CL2 axis CM camera part DC dome camera GB image shake prevention device MR memory Mp, Mt motor S image sensor SN1 image signal, SN2 sensor signal, SN3, SN5 operation signal SN3p, SN3t, SN5p, SN5t Motor drive signal SN4 input signal Sp, St Pan-tilt acceleration component Yp, Yt Shake acceleration component α1, α2 acceleration information, nα1 offset acceleration information