Shooting lens having vibration reducing function and camera system for same

Abstract

The invention includes a vibration reduction mechanism, a vibration detecting part, a reference signal generating part, a target drive position calculating part, and a driving part. The vibration reduction mechanism reduces a vibration of a subject image. The vibration detecting part outputs a vibration detection signal. The reference signal generating part estimates a reference signal of the vibration detection part. The target drive position calculating part obtains a vibration component from a difference between the vibration detection signal and the estimated reference signal to obtain a target position to which the vibration reduction mechanism is driven. The driving part controls the vibration reduction mechanism to follow the target position. Particularly, the reference signal generating part corrects the reference signal according to a motion signal obtained from a captured image. An accurate reference signal can be obtained by the correction, thereby improving the performance of the vibration reduction.

1 . A shooting lens for forming an image of a subject on an imaging plane of a camera, the shooting lens comprising: 
 a vibration reduction mechanism for reducing a vibration of the image of the subject;    a vibration detecting part which detects a vibration of the camera and outputs a vibration detection signal;    a reference signal generating part which estimates a reference signal of the vibration detection part in accordance with the vibration detection signal, the reference signal representing an output of the vibration detecting part while the camera is in a stationary state and free of vibration;    a target drive position calculating part which obtains a vibration component from a difference between the vibration detection signal and the estimated reference signal, and obtains, in accordance with the vibration component, a target position to which the vibration reduction mechanism is driven, the vibration component causing the vibration of the image; and    a driving part which controls the vibration reduction mechanism to follow the target position, wherein    the reference signal generating part acquires information on a motion signal obtained by analyzing an image shot with the camera, to correct the reference signal in accordance with the motion signal.    
   
   
       2 . The shooting lens as set forth in  claim 1 , wherein 
 the reference signal generating part corrects the reference signal to contain a drift output of the vibration detecting by feeding back the motion signal to the reference signal.    
   
   
       3 . The shooting lens as set forth in  claim 1 , wherein 
 the reference signal generating part converts a scale of the motion signal into a scale of the reference signal in accordance with a focal distance and a magnification of the shooting lens and corrects the reference signal in accordance with the motion signal of the converted scale.    
   
   
       4 . The shooting lens as set forth in  claim 1 , wherein: 
 the reference signal generating part updates the reference signal to a corrected reference signal;    the target drive position calculating part updates the target position; and    a cycle in which the reference signal generating part updates the reference signal is longer than a cycle in which the target drive position calculating part updates the target position.    
   
   
       5 . The shooting lens as set forth in  claim 1 , further comprising: 
 a phase compensating part which performs lead compensation for a phase of the motion signal, wherein    the reference signal generating part corrects the reference signal according to the phase-compensated motion signal.    
   
   
       6 . The shooting lens as set forth in  claim 1 , wherein the reference signal generating part includes: 
 a feedback path for acquiring information on a motion signal obtained by analyzing an image shot with the camera and feeding back the reference signal to the motion signal, to correct the reference signal; and    a gain changing part which obtains, from the camera, information on a timing when the camera is to start a shooting preparation for a still image, and starts or increases feedback of the feedback path after a start of the shooting preparation.    
   
   
       7 . The shooting lens as set forth in  claim 1 , wherein the reference signal generating part includes: 
 a feedback path for acquiring information on a motion signal obtained by analyzing an image shot with the camera and feeding back the motion signal to the reference signal, to correct the reference signal; and    a gain changing part which obtains, from the camera, information on a timing when the camera is to focus the image of the subject and starts or increases feedback of the feedback path after the camera has focused the image of the subject.    
   
   
       8 . The shooting lens as set forth in  claim 1 , wherein the reference signal generating part includes: 
 a feedback path for acquiring information on a motion signal obtained by analyzing an image shot with the camera and feeding back the motion signal to the reference signal, to correct the reference signal; and    a gain changing part which detects panning of the camera according to the vibration detection signal and/or the motion signal and starts or increases feedback of the feedback path after a completion of the panning.    
   
   
       9 . The shooting lens as set forth in  claim 1 , wherein the reference signal generating part includes: 
 a feedback path for acquiring information on a motion signal obtained by analyzing an image shot with the camera and feeding back the motion signal to the reference signal, to correct the reference signal; and    a gain changing part which obtains, from the camera, information on a timing when the camera is to start a shooting preparation for a still picture, and, after a start of the shooting preparation, stops or decreases feedback of the feedback path when detecting panning of the camera according to the vibration detection signal and/or the motion signal.    
   
   
       10 . A shooting lens for forming an image of a subject on an imaging plane of a camera, the shooting lens comprising: 
 a vibration reduction mechanism for reducing a vibration of the image of the subject;    a vibration detecting part which detects a vibration of the camera and outputs a vibration detection signal;    an information obtaining part which acquires information on a motion signal obtained by analyzing an image shot with the camera; and    a controlling part which controls, using the vibration detection signal, the vibration reduction mechanism to perform feedforward operation and controls, using the motion signal, the vibration reduction mechanism to perform feedback operation, thereby reducing the image vibration; and    a center bias part which biases the vibration reduction mechanism to a center position by feeding back displacement of the vibration reduction mechanism from the center position to the control over the vibration reduction mechanism; and wherein    the controlling part decreases a feedback gain of the motion signal as a feedback gain of the center bias part increases, and increases the feedback gain of the motion signal as the feedback gain of the center bias part decreases.    
   
   
       11 . The shooting lens as set forth in  claim 10 , further comprising: 
 a sensor which senses information on at least one of states of the camera which are a state that the camera is fixed by a tripod and a state that the vibration reduction mechanism has moved to its limit, wherein;    the center bias part increases the feedback gain of the center bias part in accordance with the sensed information on the state of the camera; and    the controlling part decreases the feedback gain of the motion signal in accordance with the sensed information on the state of the camera.    
   
   
       12 . A shooting lens for forming an image of a subject on an imaging plane of a camera, the shooting lens comprising: 
 a vibration reduction mechanism for reducing a vibration of the image of the subject;    a vibration detecting part which detects a vibration of the camera and outputs a vibration detection signal;    an information obtaining part which acquires information on a motion signal obtained by analyzing an image shot with the camera; and    a controlling part which controls, using the vibration detection signal, the vibration reduction mechanism to perform feedforward operation and controls, using the motion signal, the vibration reduction mechanism to perform feedback operation, thereby reducing the image vibration, wherein    for stopping the vibration reduction by the vibration reduction mechanism, the controlling part controls the vibration reduction mechanism to stop the feedback operation before stopping the feedforward operation.    
   
   
       13 . The shooting lens as set forth in  claim 12 , further comprising: 
 a sensor which senses information on at least one of states of the camera which are a state that the camera is fixed by a tripod, a state that the camera is panning, and a state that the vibration reduction mechanism has moved to its limit, wherein    the controlling part stops the feedback operation first according to the sensed information on the state of the camera and then stops the feedforward operation.    
   
   
       14 . The shooting lens as set forth in  claim 10 , wherein the controlling part comprises: 
 a reference signal estimating part which estimates a reference signal of the vibration detection signal in accordance with the vibration detection signal, the reference signal representing an output of the vibration detecting part while the camera is in a stationary state and free of a vibration;    a reference signal correcting part which corrects the reference signal by feeding back the motion signal to the reference signal estimated by the reference signal estimating part;    a target drive position calculating part which obtains a vibration component from a difference between the vibration detection signal and the corrected reference signal, and obtains, in accordance with the vibration component, a target position to which the vibration reduction mechanism is driven, the vibration component causing the vibration of the image, the vibration mechanism reducing the image vibration according to the vibration component; and    a driving part which controls the vibration reduction mechanism to follow the target position.    
   
   
       15 . The shooting lens as set forth in  claim 12 , wherein the controlling part comprises: 
 a reference signal estimating part which estimates a reference signal of the vibration detection signal in accordance with the vibration detection signal, the reference signal representing an output of the vibration detecting part while the camera is in a stationary state and free of a vibration;    a reference signal correcting part which corrects the reference signal by feeding back the motion signal to the reference signal estimated by the reference signal estimating part;    a target drive position calculating part which obtains a vibration component from a difference between the vibration detection signal and the corrected reference signal, and obtains, in accordance with the vibration component, a target position to which the vibration reduction mechanism is driven, the vibration component causing the vibration of the image, the vibration mechanism reducing the image vibration according to the vibration component; and    a driving part which controls the vibration reduction mechanism to follow the target position.    
   
   
       16 . A camera system, comprising: 
 the shooting lens as set forth in  claim 1;     an imaging part which captures an image of a subject formed by the shooting lens on an imaging plane; and    a motion detecting part which obtains a captured image from the imaging part, finds variation with time in the captured image, and outputs a motion of the subject image on the imaging plane as a motion signal.    
   
   
       17 . A camera system, comprising: 
 the shooting lens as set forth in  claim 10;     an imaging part which captures an image of a subject formed by the shooting lens on an imaging plane; and    a motion detecting part which obtains a captured image from the imaging part, finds variation with time in the captured image, and outputs a motion of the subject image on the imaging plane as a motion signal.    
   
   
       18 . A camera system, comprising: 
 the shooting lens as set forth in  claim 12;     an imaging part which captures an image of a subject formed by the shooting lens on an imaging plane; and    a motion detecting part which obtains a captured image from the imaging part, finds variation with time in the captured image, and outputs a motion of the subject image on the imaging plane as a motion signal.