Shooting lens having vibration reducing function and camera system for same

• US 7,932,926 B2
• Filed: 10/14/2009
• Issued: 04/26/2011
• Est. Priority Date: 07/25/2003
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tomita, Hiroyuki, Matsumoto, Tsuyoshi, Usui, Kazutoshi
• Primary Examiner(s): Tran; Nhan T
• Application Number:
  US12/588,400
• Publication Number:
  US 20100033583A1
• Time in Patent Office: 559 Days
• Field of Search: 348/208.1, 348/208.2, 348/208.4, 348/208.5, 348/208.7, 348/208.8, 348/208.11, 396/52, 396/55
• US Class Current: 348/208.4
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position

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.

Claims

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 which reduces 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 extracts low frequency components from the vibration detection signal and estimates a reference signal of the vibration detection part in accordance with the extracted low frequency components, the estimated reference signal varying due to an external disturbance and 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;

a position detecting part which detects a position of the vibration reduction mechanism; and

a driving part which controls the vibration reduction mechanism to follow the target position in accordance with a difference between the position detected by the position detecting part and the target position, wherein

the reference signal generating part acquires information on a motion signal obtained by analyzing an image shot with the camera, converts a scale of the motion signal into a scale of the estimated reference signal and subtracts the converted motion signal from the reference signal to correct the estimated reference signal.

2. The shooting lens as set forth in claim 1, wherein

the reference signal generating part corrects the estimated reference signal to contain a drift output of the vibration detecting part by feeding back the motion signal to the estimated 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 estimated reference signal in accordance with a focal distance and a magnification of the shooting lens and corrects the estimated 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 estimated 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 estimated 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 estimated reference signal according to the phase-compensated motion signal.

6. 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.

7. A method for controlling a shooting lens for forming an image of a subject on an imaging plane of a camera, the method comprising:

detecting a vibration of the camera and outputting a vibration detection signal;

extracting low frequency components from the vibration detection signal;

estimating a reference signal in accordance with the extracted low frequency components, the estimated reference signal varying due to an external disturbance and representing the vibration detection signal while the camera is in a stationary state and free of vibration;

obtaining a vibration component from a difference between the vibration detection signal and the estimated reference signal, and obtaining, in accordance with the vibration detecting signal, a target position to which a vibration reduction mechanism is driven, the vibration of the camera causing a vibration of the image;

detecting a position of the vibration reduction mechanism; and

controlling the vibration reduction mechanism to follow the target position in accordance with a difference between the detected position of the vibration reduction mechanism and the target position in order to control the shooting lens to reduce a vibration of the image of the subject;

acquiring information on a motion signal obtained by analyzing an image shot with the camera;

converting a scale of the motion signal into a scale of the estimated reference signal, and

subtracting the converted motion signal from the reference signal, to correct the estimated reference signal.

8. The method as set forth in claim 7, wherein:

the estimated reference signal is corrected by feeding back the motion signal to the reference signal.

9. The method as set forth in claim 7, wherein:

a scale of the motion signal is converted into a scale of the estimated reference signal in accordance with a focal distance and a magnification of the shooting lens and the estimated reference signal is corrected in accordance with the motion signal of the converted scale.

10. The method as set forth in claim 7, wherein:

the estimated reference signal is updated to a corrected reference signal;

the target position is updated; and

a cycle in which the estimated reference signal is updated is longer than a cycle in which the target position is updated.

11. The method as set forth in claim 7, further comprising:

performing lead compensation for a phase of the motion signal, wherein

the estimated reference signal is corrected according to the lead compensation for the phase of the motion signal.