JP2012042589A - Image shake correction mechanism, lens barrel, and image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image shake correction mechanism which does not deviate too much from a conventional image shake correction mechanism (i.e., using an angular velocity sensor as a vibration sensor), enables high-speed operations by adopting a simple structure, and realizes a correction mechanism in the macrophotography range.SOLUTION: The image shake correction mechanism has image shake correction control means. The image shake correction control means calculates image magnification and, in the macrophotography range (where influence of a shift shake is larger), switches sensors from an angular velocity sensor (for detecting an angular shake) to an acceleration sensor (for detecting a shift shake).

Description

  The present invention relates to an image blur correction mechanism, a lens barrel, and an imaging apparatus, and more particularly to an image blur correction mechanism for obtaining an image blur correction effect during macro photography, and a lens barrel and an imaging apparatus using the same. About.

  Some recent imaging apparatuses, particularly single-lens reflex cameras, compact cameras, and video cameras, are equipped with a mechanism for correcting image blur caused by camera shake of a photographer.

  Such an image blur correction mechanism includes an electronic image blur correction mechanism mainly used for a compact digital camera and an optical image blur correction mechanism mainly used for a single-lens reflex camera.

  The electronic image blur correction mechanism is a mechanism that generates an image with less image blur by shifting an output region of an image acquired by a digital camera in accordance with the image blur. There is also a mechanism for electronically synthesizing a plurality of images as an electronic image blur correction mechanism. These elements are often mounted on a compact digital camera or a mobile phone equipped with a camera function, which is particularly required to have a space-saving mechanism because there are very few mechanically added elements. On the other hand, the electronic image blur correction mechanism has a problem that the processing itself takes time, or the sense of resolution is lost in the process of generating an image with less image blur from a plurality of images. Therefore, development of an image processing process that does not lose a sense of resolution and development of a higher-speed image processing chip have been performed.

  The optical image shake correction mechanism detects a lens and a lens group that decenters an optical axis in order to correct image shake (hereinafter referred to as a correction lens), an actuator that moves the correction lens, and a current position of the correction lens. The image sensor includes a position sensor, a vibration sensor that detects camera shake of the photographer applied to the imaging apparatus, and a CPU that controls the movement of the correction lens so as to cancel image shake caused by camera shake of the photographer (hereinafter referred to as image shake correction CPU). Some digital cameras move an image sensor instead of a lens.

  Here, the mechanism of the optical image shake correction apparatus will be described in detail.

  The correction lens is at least one lens of a lens optical system disposed in the lens barrel, and is held movably in a plane orthogonal to the optical axis. By moving the correction lens, the imaging position on the image plane is kept constant, and an image with little image blur can be taken.

  As the actuator for moving the correction lens, an actuator having sufficient thrust and responsiveness is used in order to move the correction lens with high speed and high accuracy and to keep it at a fixed position. A voice coil motor (hereinafter referred to as “VCM”) is usually used. A coil is provided on the lens frame holding the correction lens or on the unit side of the image blur correction mechanism, and a set of permanent magnets provided at corresponding positions. At least two sets are arranged outside the correction lens, and the correction lens is moved.

  A position sensor that detects the current position of the correction lens is provided on the Hall element that detects the magnetic flux density of the voice coil motor used for the actuator or on the unit side of the image blur correction mechanism, and is provided on the lens frame that holds the correction lens. An optical position sensor that captures light emitted from the infrared light emitting diode is used.

  An angular velocity sensor or an acceleration sensor is used as a vibration sensor for detecting a camera shake of a photographer applied to the imaging apparatus. When either sensor is used, usually two are used as one set, and vibrations in the pitch direction and yaw direction or left and right shift direction and up and down shift direction are detected, and a camera shake correction CPU is used as camera shake information applied to the imaging device. Output to.

  Further, the vibration sensor is selectively used depending on the type of the imaging device. This is because the vibration that can be detected by the vibration sensor detects shift shake in the direction parallel to the imaging surface while the acceleration sensor detects angular shake in the direction in which the imaging surface tilts, This is due to the difference in camera shake that occurs depending on the characteristics of the imaging apparatus.

  In general, an acceleration sensor is used for a small imaging device such as a mobile phone. On the other hand, an angular velocity sensor is generally used for a large imaging device such as a single-lens reflex camera or a video camera. In the early days of the image blur correction mechanism, there were some equipped with both sensors, but this is not common at present.

  The CPU that controls the movement of the correction lens calculates the target value of the correction lens necessary to prevent image blur from the output of the vibration sensor, specifies the current position of the correction lens from the output of the position sensor, and corrects from these differences Determine the amount of lens movement. The actuator is controlled to move the correction lens based on the determined movement amount, and the correction lens is moved.

  The optical image blur correction apparatus repeats such an operation at high speed to perform image blur correction.

  By the way, hand shake is vibration having a frequency of 1 Hz to 10 Hz, and it can be said that it is a complicated vibration that changes in both frequency and amplitude. If camera shake is broken down into components for analysis, it can be broken down into shift shake and angular shake. Further, when each component is broken down into components, angular shake can be regarded as a combination of pitch, yaw and roll, and shift shake can be regarded as a combination of front and rear, left and right, and top and bottom.

  In general, when the photographing magnification is 0.1 times or less, image blur correction is sufficiently performed only by correcting the angular shake, but it is known that the influence of shift shake becomes large when the photographing magnification is larger than that.

  Further, as the photographing magnification increases, the influence of the shake in the focus direction (the direction of the photographing optical axis) increases. This is because shift shake occurs as a shift on the image plane in proportion to the shooting magnification, and shake in the focus direction occurs as a focus shift in proportion to the square of the shooting magnification.

  For this reason, an angular velocity sensor is conventionally used for an image blur correction mechanism of a single-lens reflex camera. In an optical apparatus having a high photographing magnification such as a macro lens, an acceleration sensor is used in addition to the angular velocity sensor, and two types of vibration sensors are used. There has been proposed a mechanism for calculating an image blur correction amount from the vibration of the camera shake detected by the method (for example, Patent Document 1).

  In the invention shown in Patent Document 1, an angular shake displacement amount (pitch, yaw direction) obtained from a parallel shake displacement amount based on an acceleration sensor output calculated by a shake displacement calculation unit and a detection result by an angular velocity sensor in a shake synthesis unit. ) To determine the driving amount (shake correction amount) of the correction lens. More specifically, the shake displacement amount due to the parallel shake in the X direction and the shake displacement amount on the image plane due to the angular shake in the yaw direction are combined, and the shake displacement amount due to the parallel shake in the Y direction and the pitch direction displacement are combined. The amount of shake displacement on the image plane due to angular shake is synthesized. Then, the driving amount and direction of the correction lens are determined from the combined shake displacement amount.

  In the invention shown in Patent Document 2, shift shake is obtained as an angular shake when the center of rotation of the shake is at a location away from the camera, and the angular shake is obtained from integration of the angular velocity sensor output provided separately, and their synthesis. Perform shake correction with the signal.

  The output of the acceleration sensor is susceptible to environmental changes such as disturbance noise and temperature, particularly in the frequency range of camera shake. In Patent Document 1, since an acceleration sensor for detecting the acceleration of the camera body is provided and shift shake is obtained from the second order integration of the output of the acceleration sensor, those instability factors are further enlarged, and it is difficult to correct shift shake with high accuracy. There is a problem.

  In the method of Patent Document 2, since the radius of rotation can be calculated from the output of the first-order integral of the output of the acceleration sensor, the instability factors of the acceleration sensor as described above can be reduced.

  However, in the method disclosed in Patent Document 1, since the image blur correction is performed in cooperation with the acceleration sensor and the angular velocity sensor, the correction according to the phenomenon is possible, but the mechanism using any one of the sensors is possible. The calculation is more complicated than that, and there is a disadvantage that the response is delayed with respect to camera shake. On the other hand, if a desired processing speed is to be obtained, a CPU capable of higher-speed calculation is required, which directly leads to an increase in cost.

  In addition, even if the method disclosed in Patent Document 2 with high calculation accuracy is used, it is inevitable that the error of the two sensors affects the calculation of the shake displacement amount. There is a limit to the improvement. In particular, in image blur correction that requires high-speed computation, since approximation is frequently used in the course of computation, further error enlargement must be avoided.

  Further, such a mechanism has a drawback that the image blur correction CPU used in the conventional mechanism cannot be diverted because there are the number of inputs and processes of the sensor which are not assumed in the conventional mechanism. This has the inconvenience that the tuning know-how accumulated by the conventional mechanism cannot be diverted.

JP 2006-003439 A JP 2010-096938 A

Image blur that does not greatly deviate from the existing image blur correction mechanism that uses an angular velocity sensor as a vibration sensor, and that can achieve high-speed calculation by adopting a simple configuration and can achieve a correction effect in the macro region. A correction mechanism is provided.

  The invention described in claim 1 is an image shake correction mechanism provided in an optical apparatus, comprising a correction lens for image shake correction, correction lens position detection means for detecting the position of the correction lens, and shift shake. Shift shake detection means for detecting, angle shake detection means for detecting angular shake, correction lens moving means for moving the correction lens, photographic image magnification calculation means for calculating the photographic image magnification of the optical device, and the shift Image blur correction control means for calculating the amount of movement from the shake signal detected by the shake detection means or the angular shake detection means and the current position of the correction lens position detection to the target position and controlling the correction lens movement means The image shake correction control means includes the shift shake detection means or the angle shake detection means based on the photographed image magnification calculated by the photographed image magnification calculation means. An image blur correction mechanism, characterized in that for driving the correction lens moving means using either one of the signal means.

  According to the second aspect of the present invention, the image shake correction control means calculates the shift shake detection means by the photographic image magnification calculation means when the photographic image magnification calculated by the photographic image magnification calculation means is large. 2. The image blur correction mechanism according to claim 1, wherein when the photographic image magnification is small, the correction lens moving unit is driven using the angular shake detection unit.

  According to a third aspect of the present invention, in the image blur correction mechanism according to any one of the first and second aspects, the shift shake detecting means is an acceleration sensor.

  According to a fourth aspect of the present invention, in the image blur correction mechanism according to any one of the first to third aspects, the angular shake detection unit is an angular velocity sensor.

  With these configurations, in a macro region where the influence of shift shake is large, a correction effect in the macro region can be obtained by switching the sensor from an angular velocity sensor that detects angular shake to an acceleration sensor that detects shift shake. On the other hand, a simple configuration that does not greatly deviate from an existing image blur correction mechanism using an angular velocity sensor as a vibration sensor is realized.

  A fifth aspect of the present invention is a lens barrel including the image blur correction mechanism according to any one of the first to fourth aspects.

  A sixth aspect of the present invention is an image pickup apparatus including the image blur correction mechanism according to any one of the first to fifth aspects.

According to the present invention, the correction effect in the macro region can be achieved while allowing a high-speed calculation by adopting a simple configuration without greatly deviating from an existing image blur correction mechanism using an angular velocity sensor as a vibration sensor. An image blur correction mechanism that can be obtained can be provided.

  The preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram of a main part structure and a control system of a single-lens reflex camera constructed by applying the present invention. In FIG. 1, reference numeral 1 denotes a camera body, and 3 denotes a lens barrel that is detachably attached to the camera body 1.

  The lens barrel 3 is equipped with the following devices.

  5 is a lens structure, 7 is a correction lens for correcting image shake, 9 is a position sensor for detecting the position of the correction lens, 11 is an acceleration sensor for detecting shift shake, and 13 is for detecting angular shake. An angular velocity sensor, 15 is an image blur correction lens driving device for moving the correction lens, and 17 is a vibration of camera shake detected by the acceleration sensor or the angular velocity sensor, and a movement amount for driving the correction lens from the current position of the correction lens to the target position. Image blur correction CPU for controlling the correction lens driving device by calculating the above, 19 for the aperture device, 21 for the aperture motor drive circuit for driving the motor as the drive source of the aperture device, 23 for the focusing lens, and 25 for the focusing lens drive mechanism A focusing motor drive circuit for driving the motor, 27 is a CPU on the camera body side (hereinafter abbreviated as camera CPU). To) 63 and information communicable lens built-in CPU (hereinafter, abbreviated as lenses CPU), 29 is a mount for mechanically coupling the camera body 1 and the lens barrel 3.

  On the other hand, the following device is mounted on the camera body 1.

  31 is a known pentaprism, 33 is a finder eyepiece, 35 is a known photometric element such as an SPC (silicon photodiode), and 37 is a photometric circuit that calculates the field luminance based on the output signal of the element 35. 39 is a known mirror that can be moved up and down, 41 is a mirror drive motor for moving the mirror 39 up and down, 43 is a mirror drive circuit that drives the motor 41, and 45 is a known distance measuring element comprising a CCD line sensor or the like. , 47 is a focus detection circuit for detecting the focal length of the subject from the output of the element 45, 49 is a shutter, 51 is a shutter drive circuit for controlling the drive source of the shutter, and 53 is a film in a film camera or a solid-state imaging in a digital camera. The image pickup surface on which the element is located, 55 is a display unit made up of a known liquid crystal device, etc., and 57 is the photographer. A release button for transmitting a signal by a pushing operation, 59 is a mode dial for switching the exposure mode of the camera, 61 is a power source, 63 is an electrical contact provided on the mount 29 for connecting the camera body 1 and the lens barrel 3 The camera CPU is connected to the lens CPU 27 via a serial transmission line 65. The camera CPU 63 controls the operation of each component of the camera body 1 and communicates with the lens CPU 27.

  The image shake correction mechanism according to the present invention is a mechanism having a correction lens 7, a position sensor 9, an acceleration sensor 11, an angular velocity sensor 13, an image shake correction lens driving device 15, and an image shake correction CPU 17.

  Next, the main operation of the system shown in FIG. 1 will be described using the flowchart of FIG.

  (Step # 100) First, when the power supply 61 in the camera body 1 is turned on, power is supplied from the camera body 1 to the lens barrel 3, and communication between the camera CPU 63, the lens CPU 27, and the image blur correction CPU 17 is started. . Initially, initialization is performed, and the lens CPU 27 transmits various types of information including the distance between principal points unique to the lens to the image blur correction CPU 17.

  (Step # 101) Next, it is determined whether or not the release button in the camera body 1 has been half-pressed (1st release). The release button is normally a switch that can be pushed in two steps, and has a structure that can discriminate between half-press (1st release) and full-press (2nd release). If it is determined that the release button has been half-pressed, the process proceeds to step # 103. If not, step # 101 is repeated.

  (Step # 103) Subsequently, it is determined whether or not the image blur correction mechanism is ON. The image blur correction mechanism can be turned on or off by a slide switch or a GUI (graphic user interface) provided on the camera body 1 or the lens barrel 3. If the image blur correction mechanism is ON, the process proceeds to step # 105. If OFF, the process proceeds to step # 125.

  (Step # 105) In step # 105, the camera CPU 63 performs photometry and focus detection operation, and the lens CPU 27 performs focus operation based on the focus detection result, as well as the focal length (zoom position) and the shooting distance (focus position). Detection is performed.

  (Step # 107) Subsequently, the lens CPU 27 transmits the focal length (zoom position) and photographing distance (focus position) detected in step # 105 to the image blur correction CPU 17. The image blur correction CPU 17 calculates a photographed image magnification from the focal length, the photographing distance, and the principal point distance received from the lens CPU 27.

  Here, a method of calculating the photographic image magnification will be described.

  First, take a thin model as an example. First, the focal length of the thin lens is f, the distance from the main point of the thin lens to the subject is a, the distance from the main point of the thin lens to the image plane is b, the shooting distance is D, the size of the subject is L, the subject If the size on the image plane is 1, the photographed image magnification M is given by Equation 1 because of the similar relationship.

  Here, the shooting distance D is expressed by Equation 2.

  Furthermore, from the similar relationship shown in Equation 3, the photographic image magnification M of the thin model can be expressed by Equation 4 from the focal length f and the photographic distance D.

  Here, in the case of a thick model with a distance h between the principal points, the shooting distance D is expressed by Equation 5.

  That is, the photographed image magnification M in the thick model is as shown in Equation 6.

  Accordingly, the image blur correction CPU 17 calculates the photographic image magnification M from the focal length f, the photographic distance D, and the principal point distance h received from the lens CPU 27.

  (Step # 109) In step # 109, it is determined whether or not the photographic image magnification calculated in step # 107 is larger than the default photographic image magnification. If the result of determination is that the captured image magnification is greater than a predetermined value, the process proceeds to step # 111. As a result of the determination, if the photographed image magnification is not larger than the predetermined value, the process proceeds to step # 113.

  (Step # 111) In step # 111, the image blur correction CPU 17 sets the output of the vibration sensor in the acceleration sensor 11.

  (Step # 113) In step # 113, the image blur correction CPU 17 sets the output of the vibration sensor in the angular velocity sensor 13.

  (Step # 115) Subsequently, the process proceeds to step # 115, and image blur correction driving is performed based on the output of the vibration sensor and the output of the image blur correction lens position sensor set in the previous step.

  (Step # 117) Next, it is determined whether or not the release button in the camera body 1 is fully pressed (2nd release). If it is determined that the release button has been fully pressed, the process proceeds to step # 119, and if not, the process returns to step # 101.

  (Step # 119) In step # 119, the camera CPU 63 performs an exposure operation, and the lens CPU 27 performs an aperture operation in accordance with the exposure operation. During this time, image blur correction driving is performed.

  (Step # 121) Subsequently, when the process proceeds to step # 121, the image data obtained by the exposure operation is recorded.

  (Step # 123) In step # 123, it is determined whether or not the power source of the camera body 1 is turned off. If the power source in the camera body 1 is turned off, the process proceeds to step # 127, and this flow ends. Otherwise, the process returns to step # 101.

  In the first embodiment, an example in which the photographed image magnification is calculated by the calculation by the image blur correction CPU 17 in step # 107 is shown. In the second embodiment, a table capable of determining the photographic image magnification is stored in the image blur correction CPU 17 from the focal length, the shooting distance, and the distance between the principal points. The image blur correction CPU 17 receives the focal length received from the lens CPU 27, The photographed image magnification can be determined from the photographing distance and the distance between the principal points.

As a feature of the second embodiment, since the complicated calculation as in the first embodiment is not required, the processing capability of the image blur correction CPU 17 can be used for the image blur correction operation itself.

It is a block diagram which shows the single-lens reflex camera in the Example of this invention. It is a flowchart in the Example of this invention.

DESCRIPTION OF SYMBOLS 1 Camera body 3 Lens barrel 5 Lens structure 7 Correction lens 9 Position sensor 11 Acceleration sensor 13 Angular velocity sensor 15 Image blur correction lens drive device 17 Image blur correction CPU
19 Aperture Device 21 Aperture Motor Drive Circuit 23 Focusing Lens 25 Lens CPU
29 mount 31 pentaprism 33 finder eyepiece 35 photometry element 37 photometry circuit 39 mirror 41 mirror drive motor 43 mirror drive circuit 45 distance measurement element 47 focus detection circuit 49 shutter 51 shutter drive circuit 53 imaging surface 55 display 57 release button 59 mode Dial 61 Power supply 63 Camera CPU
65 Electrical contacts

Claims (6)

An image shake correction mechanism provided in an optical apparatus,
A correction lens for image blur correction;
Correction lens position detection means for detecting the position of the correction lens;
Shift shake detection means for detecting shift shake;
Angular shake detection means for detecting angular shake;
Correction lens moving means for moving the correction lens;
A photographic image magnification calculating means for calculating a photographic image magnification of the optical device;
Image blur correction for calculating the amount of movement from the shake signal detected by the shift shake detection means or the angular shake detection means and the current position of the correction lens position detection to the target position, and controlling the correction lens movement means Control means,
The image shake correction control means drives the correction lens moving means using one of the shift shake detection means and the angle shake detection means based on the photographed image magnification calculated by the photographed image magnification calculation means. An image blur correction mechanism characterized in that The image shake correction control unit is configured to detect the shift shake detection unit when the photographic image magnification calculated by the photographic image magnification calculation unit is large, and to detect when the photographic image magnification calculated by the photographic image magnification calculation unit is small. 2. The image blur correction mechanism according to claim 1, wherein the correction lens moving unit is driven using the angular shake detection unit. 3. The image blur correction mechanism according to claim 1, wherein the shift shake detection unit is an acceleration sensor. The image shake correction mechanism according to claim 1, wherein the angular shake detection unit is an angular velocity sensor. A lens barrel provided with the image blur correction mechanism according to any one of claims 1 to 4. An imaging apparatus comprising the image blur correction mechanism according to claim 1.

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