JP2012208335A - Image blurring correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image blurring correction device that conforms to variation in amplitude in a small to large wide range and has less limitation of lens constitution.SOLUTION: To a photographing lens 4, a first correction lens 11 and a second correction lens 12 are provided. The correction lenses 11 and 12 have same optical correction sensitivity. The first correction lens 11 is displaced by VCMs 21 and 22 driven on the basis of a blur angle of a low frequency component of oscillation and the second correction lens 12 is displaced by VCMs 25 and 26 driven on the basis of a blur angle of a high frequency component of oscillation. Strokes of the VCMs 21 and 22 are made relatively longer, and the VCMs 25 and 26 have small displaceable amounts and high responsiveness.

Description

  The present invention relates to an image blur correction apparatus used for a photographing lens such as a surveillance camera.

  In recent years, there have been an increasing number of photographing devices such as digital cameras and video cameras that incorporate an image blur correction device that performs camera shake correction. As for the camera shake correction, an electronic type and an optical (mechanical) type are known. The electronic image blur correction apparatus compares a predetermined area of each frame sequentially obtained from the imaging unit and obtains a correlation between the two, thereby orthogonal to the optical axis of the image of the subsequent frame with respect to the image of the preceding frame. The moving direction and the moving amount of the direction are detected, and the range of the image that is cut out from the imaging range of the image sensor and output is shifted by the moving amount in the direction opposite to the moving direction (for example, Patent Document 1). reference).

  On the other hand, an optical image blur correction device detects a shake angle of an imaging device based on a detection result of an angular velocity sensor or the like, and displaces a correction lens arranged in a photographing lens according to the shake angle. The movement due to the shake of the optical image formed on the image sensor is canceled out.

  There are various vibrations applied to the photographing apparatus. Generally, vibrations with a high frequency have a small amplitude, and vibrations with a low frequency have a large amplitude. Therefore, two types of correction lenses with high and low optical correction sensitivity, ie, high and low optical correction sensitivity, are used to correct high-frequency vibration with a low-sensitivity correction lens and low-frequency vibration with a high-sensitivity correction lens A photographic lens is known (see Patent Document 2). With this configuration, the photographic lens of Patent Document 2 is adapted to handle vibrations in a frequency band such as camera shake and vibration during operation of a quick return mirror of a single-lens reflex camera while maintaining image quality.

JP-A-1-109970 JP 2003-295250 A

  Since the electronic image blur correction apparatus as described above cuts out an image from the imaging range of the image sensor, the number of effective pixels is reduced, resulting in image quality degradation. In order to suppress this image quality degradation, the size of the range of the image to be cut out is limited to about 90% of the imaging range. As a result, only an optical image displacement of about 10% of the imaging range can be dealt with, and the correction amount is considerably small. For example, when the shooting angle of view is 10 degrees, the correctable deflection angle is 1 degree, and a sufficient correction effect cannot be obtained.

  By the way, surveillance cameras installed on ships, mountain peaks, steel towers, and the like monitor a point several kilometers away, so the shooting angle of view may be extremely small. For example, when an image sensor with a 1/2 type aspect ratio 16: 9 and a photographing lens with a focal length of 2000 mm are combined, the photographing field angle in the V (vertical) direction is 0.11 degrees, and the electronic type as described above is used. In the image blur correction apparatus, the maximum shake angle that can be corrected is 0.01 degrees. For this reason, an electronic image blur correction apparatus is not suitable for such a monitoring camera.

  In addition, in the surveillance cameras as described above, from low-frequency vibrations such as ship shakes and towers caused by waves to low frequency vibrations, high-frequency vibrations due to vibrations of the housing housing the photographic lens, vibrations due to strong winds, etc. Will be added. In addition, the range of amplitude is considerably larger than the range of daily use environments, and there are also large amplitudes that are not expected in daily use environments. For example, some low frequency vibrations have a swing angle of ± 8 degrees, and high frequency vibrations have a fine swing angle of ± 0.001 degrees. For this reason, even if it is satisfactory in the daily use environment as described in Patent Document 1, the surveillance camera has not been able to correct image blur sufficiently. Furthermore, incorporating two types of correction lenses having different optical correction sensitivities as in Patent Document 1 into the photographing lens has a problem that the degree of freedom in designing the lens optical system is reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image blur correction apparatus that is capable of dealing with amplitude fluctuations in a large and small range and that has a small lens configuration restriction.

  In order to solve the above-described problem, in the image blur correction device of the present invention, the first and second correction lenses for correcting the image blur, the responsiveness is relatively lowered, and the stroke is lengthened. The first actuator that is displaced, the second actuator that increases the response and the stroke is shortened, and that displaces the second correction lens, and the shake signal is separated into a low frequency component and a high frequency component, and based on the low frequency component Drive control means for driving the first actuator and driving the second actuator based on a high frequency component.

  The first actuator and the second actuator are preferably voice coils.

  According to the present invention, of the first and second correction lenses having the same optical correction sensitivity, the first correction lens is displaced by an actuator having a relatively low response and a long stroke. (2) The correction lens is displaced by a second actuator having high response and a short stroke, and the first actuator is driven based on the low frequency component of the shake signal, and the second actuator is driven based on the high frequency component. As a result, image blur can be corrected in response to vibrations of a wide range of large and small amplitudes while reducing the restrictions on the lens configuration.

It is a schematic diagram which shows the structure of the surveillance camera by this invention. It is a perspective view of each vibration isolator unit. It is a block diagram which shows the electrical structure of the principal part of a surveillance camera. It is a block diagram which shows the structure of a X direction correction | amendment control part. It is a principle figure which shows the whole structure of an image blurring correction apparatus.

  As shown in FIG. 1, the monitoring camera 2 includes a photographing lens 4 having an image blur correction device 3 and a camera body 5. Each part of the surveillance camera 2 is centrally controlled by the main control unit 6. The photographing lens 4 includes a plurality of lenses G1 to G5 driven by a lens driving mechanism 7, an aperture device 8, a first correction lens 11, and a second correction lens 12.

  The lens G1 is a focusing lens, and is moved in the optical axis direction so that the subject is in focus. The lenses G2 and G3 are zoom units that continuously change the focal length of the photographing lens 2. The lens G2 is a variator and the lens G3 is a compensator. The lenses G2 and G3 both move in the optical axis direction.

  The lens G4 is an extender lens for switching the focal length, and is moved to a retracted position retracted from the optical path and an insertion position inserted into the optical path as indicated by a two-dot chain line as shown in the figure. By setting the lens G4 to the insertion position, the focal length of the photographing lens 4 is increased at a predetermined magnification. The lens G5 is a tracking lens for adjusting the flange back, and is movable in the optical axis direction.

  The aperture device 8 has aperture blades 8a arranged in the optical path. The amount of photographing light incident on the camera 5 is adjusted by increasing or decreasing the diameter of the aperture opening formed by the aperture blades 8a.

  The image blur correction device 3 includes a first image stabilization unit 14 including a first correction lens 11, a second image stabilization unit 15 including a second correction lens 12, a control unit 16, and the like. A direction gyro sensor 17, a Y direction gyro sensor 18, a control circuit, and the like are incorporated.

  Each of the correction lenses 11 and 12 corrects image blur and is disposed in the optical path of the photographing lens 4 and is independently displaced. Among these, the 1st correction | amendment lens 11 is provided in order to respond to a low frequency vibration. The second correction lens 12 is provided to cope with high frequency vibration. Note that each of the correction lenses 11 and 12 does not need to be composed of a single lens, and may be composed of a plurality of lenses.

  The first correction lens 11 and the second correction lens 12 have the same optical correction sensitivity, that is, the displacement amount of the optical image displaced with respect to the displacement amount of the lens. Further, the first correction lens 11 and the second correction lens 12 have no optical stroke difference. For this reason, for example, a set of correction lens systems incorporated in a photographic lens is separated into two correction lenses with equal power distribution to form two sets of correction optical systems, one set as the first correction lens 11 and the other set as the first correction lens system. It can also be configured to have two correction lenses 12. Accordingly, it is possible to use a lens optical system that has been configured with one set of correction lens systems with relatively easy modifications. Further, even a lens optical system that can originally constitute only one set of correction optical systems can be used.

  In this example, the first correction lens 11 and the second correction lens 12 are assumed to have no difference in optical correction sensitivity and optical stroke, but they may have a difference. In this case, it is preferable to increase the optical correction sensitivity of the first correction lens 11 corresponding to the low-frequency vibration, and it is also possible to increase the optical stroke of the first correction lens 11.

  The X-direction gyro sensor 17 detects a shake angular velocity in the X direction of the X direction and the Y direction that are orthogonal to the optical axis PL of the photographing lens 4 and orthogonal to each other, and outputs an angular velocity signal. Similarly, the Y direction gyro sensor 18 detects a shake angular velocity in the Y direction and outputs an angular velocity signal.

  The camera body 5 is attached to the rear end of the photographing lens 4 via a mount M. The camera body 5 has a built-in image sensor 5a, and converts an optical image formed by the photographing lens 4 into an electrical image signal and outputs it. The imaging signal is subjected to various signal processing and sent to a monitor (not shown). Thereby, an image photographed by the camera body 5 through the photographing lens 4 can be viewed.

  In FIG. 2, the first image stabilization unit 14 holds the first correction lens 11 so as to be movable in the X direction and the Y direction. The first image stabilization unit 14 is provided with an X-direction VCM (voice coil motor) 21 and a Y-direction VCM 22 as actuators for displacing the first correction lens 11. The X direction VCM 21 moves the first correction lens 11 in the X-axis direction, and the Y direction VCM 22 moves the first correction lens 11 in the Y direction.

  The first vibration isolation unit 14 is provided with an X direction position sensor 23 and a Y direction position sensor 24. The X direction position sensor 23 detects the lens position of the first correction lens 11 in the X direction, and the Y direction position sensor 24 detects the lens position of the first correction lens 11 in the Y direction.

  Similarly, the second image stabilization unit 15 holds the second correction lens 12 so as to be movable in the X and Y directions. Further, an X-direction VCM 25 and a Y-direction VCM 26 are provided as actuators for displacing the second correction lens 12. The second correction lens 12 is corrected in the X-axis direction by the X-direction VCM 25 and second corrected by the Y-direction VCM 26. The lens 12 is moved in the Y direction. Further, the X-direction position sensor 27 detects the lens position of the second correction lens 12 in the X direction, and the Y-direction position sensor 28 detects the position of the second correction lens 12 in the Y direction.

  The VCMs 21 and 22 correct the image blur due to the low-frequency vibration component having a large amplitude by displacing the first correction lens 11, and the VCMs 25 and 26 change the high-frequency having a small amplitude by displacing the second correction lens 12. Correct image blur due to vibration components. The amount of displacement by which the correction lens can be displaced, that is, the stroke of the VCM is relatively longer for the VCMs 21 and 22 and shorter for the VCMs 25 and 26, and the correction lenses 11 and 12 having the same optical correction sensitivity. Among these, the displacement amount that can be displaced is increased for the first correction lens 11, and the displacement amount that can be displaced is decreased for the second correction lens 12.

  By increasing the stroke, the VCM 21 and 22 have a response speed that is displaced to a predetermined position corresponding to the input of the drive signal, that is, the response is lowered. However, the displacement speed of the image due to the low-frequency vibration component is Since it is slow, it can cope with this, so it is not a problem. On the other hand, the VCMs 25 and 26 have high responsiveness by reducing the stroke, and can cope with image displacement due to high-frequency vibration components. Further, since the VCMs 25 and 26 have a small stroke, it is possible to finely control the amount of displacement of the second correction lens 12 corresponding to the minute amplitude of the high frequency component of vibration.

  The control unit 16 serves as drive control means for driving the VCMs 21, 22, 25, and 26 based on shake signals. As shown in FIG. 3, the control unit 16 includes an X direction correction control unit 41 and a Y direction correction control unit 42. Become. The X direction correction control unit 41 controls the driving of the X direction VCMs 21 and 25 based on the angular velocity signal from the X direction gyro sensor 17 described above. The Y direction correction control unit 42 controls the driving of the Y direction VCMs 22 and 26 based on the angular velocity signal from the Y direction gyro sensor 18.

  The configuration of the X direction correction control unit 41 is shown in FIG. The angular velocity signal from the X direction gyro sensor 17 is sent to the amplifier 43. The amplifier 43 amplifies and outputs a weak angular velocity signal with a predetermined gain. The A / D converter 44 digitally converts the angular velocity detection signal amplified by the amplifier 43 into angular velocity data by sampling at a predetermined sampling period. This angular velocity data is sent to an LPF (low pass filter) 45 and an HPF (high pass filter) 46.

  The LPF 45 outputs low-frequency angular velocity data corresponding to a low-frequency vibration component below the reference frequency, for example, 1 Hz or less, among the angular velocity signals by performing arithmetic processing on the angular velocity data that is sequentially input. Similarly, the HPF 46 performs arithmetic processing on the angular velocity data and outputs high-frequency angular velocity data of a high-frequency vibration component exceeding the reference frequency in the angular velocity signal.

  Low frequency angular velocity data from the LPF 45 is sent to the integration circuit 47. The integration circuit 47 performs an integration process using the input low frequency angular velocity data. In this integration processing, the shake angle is obtained from the low frequency angular velocity data, and the obtained shake angles are sequentially added to calculate the cumulative shake angle θx1 of the low frequency component of the shake of the surveillance camera 2 in the X direction. The shake angle is an angle at which the monitoring camera 2 is shaken in the X direction by a low frequency component of vibration during one period of sampling the angular velocity signal, and the accumulated shake angle θx1 is a reference (“0”) when the monitoring camera 2 is stationary. ) Is an angle at which the monitoring camera 2 is swung in the X direction by the low frequency component of vibration from the reference.

  In addition, the integration circuit 47 is provided with a centering processing unit 47a for returning the first correction lens 11 to the origin position when the monitoring camera 2 is stationary. The centering processing unit 47a is for returning the first correction lens 11 to the origin position when the monitoring camera 2 is stationary (low frequency component of vibration is “0”). Converge toward "0".

  The cumulative deflection angle θx1 from the integration circuit 47 is input to the drive circuit 48. The drive circuit 48 converts the accumulated deflection angle θx1 into a drive signal that is a voltage signal, and drives the X-direction VCM 21 with this drive signal. The driving circuit 48 receives the X-direction lens position of the first correction lens 11 from the X-direction position sensor 23, and feedback-controls the X-direction VCM 21 based on this lens position. As a result, the first correction lens 11 is displaced by the X direction VCM 21 to a position corresponding to the cumulative deflection angle θx1.

  High frequency angular velocity data from the HPF 46 is sent to the integrating circuit 51. The integration circuit 51 is the same as the integration circuit 47, but uses the input high-frequency angular velocity data to determine and output the cumulative shake angle θx2 of the high and low frequency vibration components of the shake in the X direction. In the integration circuit 51, the centering processing unit 51a converges the cumulative shake angle θx2 toward “0” when the monitoring camera 2 is stationary.

  The drive circuit 52 converts the cumulative deflection angle θx2 from the integration circuit 51 into a drive signal, and drives the X direction VCM 25 with the drive signal while feedback controlling the X direction VCM 25 based on the lens position. As a result, the second correction lens 12 is displaced by the X direction VCM 25 to a position corresponding to the cumulative deflection angle θx2.

  Note that the direction in which the correction lenses 11 and 12 are to be displaced can be identified by assigning the cumulative shake angles θx1 and θx2 to a sign corresponding to the shake direction of the monitoring camera 2.

  The Y direction correction control unit 42 generates drive signals for driving the Y direction VCM 22 and the Y direction VCM 26 based on the detection result of the Y direction gyro sensor 18 in order to correct the shake in the Y direction. It is. Since the configuration of the Y-direction correction control unit 42 is the same as that of the X-direction correction control unit 41, detailed description thereof is omitted.

  The overall configuration of the image blurring device 3 is shown in FIG. 5 as a principle diagram.

  Next, image blur correction according to the above configuration will be described. In the following description, a case where the surveillance camera 2 is swung in the X direction will be described as an example. An angular velocity signal from the X-direction gyro sensor 17 is amplified by the amplifier 43, sampled at a predetermined sampling period by the A / D converter 44, and converted into angular velocity data. The angular velocity data thus obtained is sent to the LPF 45 and the HPF 46, respectively.

  Low frequency angular velocity data corresponding to the angular velocity of the low frequency component of vibration is obtained by the LPF 45, and this is sent to the integrating circuit 47. By sequentially inputting the low frequency angular velocity data to the integration circuit 47, the integration circuit 47 calculates the cumulative shake angle θx1 of the low frequency component in the X direction of the monitoring camera 2. The cumulative deflection angle θx1 is sent to the drive circuit 48.

  On the other hand, high-frequency angular velocity data corresponding to the angular velocity of the high-frequency component of vibration is output from the HPF 46 and sent to the integrating circuit 51. As a result, the cumulative deflection angle θx2 of the high-frequency component in the X direction of the monitoring camera 2 is output from the integration circuit 51 and sent to the drive circuit 52.

  As described above, the cumulative shake angle θx1 of the low frequency component is input to the drive circuit 48, and the X-direction VCM 21 is driven based on the cumulative shake angle θx1. Further, the cumulative shake angle θx2 of the high frequency component is input to the drive circuit 52, and the X direction VCM 25 is driven based on the cumulative shake angle θx2. As a result, the first correction lens 11 is displaced to the position in the X direction corresponding to the cumulative shake angle θx1 by the X direction VCM21, and the second correction lens 12 is moved in the X direction corresponding to the cumulative shake angle θx2 by the X direction VCM25. Displaced to position.

  When the angular velocity data is obtained again, the X-direction VCM 21 is driven by the drive circuit 48 based on the low-frequency component cumulative shake angle θx1 obtained by the same procedure as described above, and the first correction lens 11 is displaced. Further, the X-direction VCM 25 is driven by the drive circuit 52 based on the cumulative deflection angle θx2 of the high frequency component, and the second correction lens 12 is displaced. Thereafter, the displacement of the first lens 11 and the second lens 12 is repeated in the same procedure.

  In this way, the first correction lens 11 is sequentially displaced to a position corresponding to the cumulative shake angle θx1, and the displacement of the optical image due to the low frequency component of vibration is canceled by the displacement in the X direction at that time. The second correction lens 12 is sequentially displaced to a position corresponding to the cumulative deflection angle θx2, and the displacement of the optical image due to the high frequency component of vibration is canceled by the displacement in the X direction at that time.

  Although the image blur due to the vibration of the monitoring camera 2 is corrected by canceling the displacement of the optical image as described above, the amplitude of the low-frequency component of the vibration may be quite large. However, since the stroke of the X direction VCM 21 is large, the first correction lens 11 can be greatly displaced in the X direction correspondingly, and image blur due to this can be corrected. On the other hand, since the amplitude of the high-frequency component of vibration is small, the increase / decrease in the cumulative deflection angle θx2 is small, but the increase / decrease repetition cycle is short. However, since the VCMs 25 and 26 increase the responsiveness by reducing the stroke, the second correction lens 12 is displaced following the increase / decrease in the cumulative shake angle θx2, and image blur due to the high-frequency vibration component occurs. It is corrected.

  In the above-described embodiment, an example in which a voice coil motor is used as an actuator has been described. However, the present invention is not limited to this, and any other type may be used as long as the stroke response is as described above. A linear control actuator can be used.

  Further, in the above embodiment, the vibration is separated into the high frequency component and the low frequency component. However, the vibration is separated into three or more bands such as a high frequency component, a low frequency component, and an intermediate frequency band component. A configuration may be adopted in which a correction lens is provided corresponding to each.

2 surveillance camera 3 image blur correction device 4 taking lens 5 camera body 6 main control unit G1 to G5 lens 11 first correction lens 12 second correction lens 21, 22, 25, 26 VCM
41, 42 Correction control unit 45 LPF
46 HPF

Claims (2)

In the image blur correction device that corrects the image blur by displacing the lens arranged in the optical path of the shooting lens based on the shake signal that detects the shake of the shooting lens,
First and second correction lenses for correcting image blur;
A first actuator that relatively lowers responsiveness and lengthens the stroke to displace the first correction lens, and a second actuator that increases responsiveness and shortens the stroke to displace the second correction lens;
Drive control means for separating a vibration signal into a low-frequency component and a high-frequency component, driving the first actuator based on the low-frequency component, and driving the second actuator based on the high-frequency component; Image blur correction device.   The image blur correction apparatus according to claim 1, wherein the first actuator and the second actuator are voice coils.

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