Television – Camera – system and detail – Camera image stabilization
Reexamination Certificate
1998-12-09
2004-05-11
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Camera image stabilization
C348S208500, C396S055000
Reexamination Certificate
active
06734902
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration correcting device for optically correcting vibration generated in a picked-up image for example by hand shaking, and an image pickup device, an image pickup system, a camera unit and a lens unit provided with such vibration correcting device.
2. Related Background Art
In an image pickup apparatus such as a video camera, automation and multiplication are made in all the functions such as by auto exposure (AE) or auto focusing (AF) in order to enable satisfactory image pickup operation in an easy manner.
Also in consideration of a fact that, with the compactization of the image pickup apparatus and with the increase in the magnification of the optical system, the vibration of the apparatus is a major factor deteriorating the quality of the picked-up image, there have recently been proposed various vibration correcting functions for correcting the vibration generated in the picked-up image by the vibration of such apparatus (namely vibration in the supporting hand). A further satisfactory image pickup operation can be easily achieved by providing the image pickup apparatus with such vibration correcting function.
As the vibration correcting function adapted for use in an image pickup apparatus for obtaining a picked-up image by focusing the light from the object on the image pickup face of an image pickup element, there is known a configuration as shown in FIG.
11
.
In such vibration correcting function
600
, an angular velocity detection sensor
601
is composed of an angular velocity sensor such as a vibration gyro, and, being mounted on the main body of the image pickup apparatus, detects the vibration thereof as an angular velocity.
A DC cut-off filter
602
cuts off the DC component of an angular velocity signal outputted from the angular velocity detection sensor
601
and only transmits the AC component, that is, the vibration component.
An amplifier
603
amplifies the angular velocity signal from the DC cut-off filter
602
to an appropriate sensitivity level.
An analog/digital (A/D) converter
604
digitizes the angular velocity signal outputted from the amplifier
603
.
A high-pass filter (HPF)
605
, an integrator
606
and a pan/tilt discrimination circuit
607
are composed for example of a microcomputer COM.
The high-pass filter
605
can variably change characteristics thereof with an arbitrary frequency range, and outputs the digital angular velocity signal (angular velocity data) from the A/D converter
604
after cutting off the low frequency component contained therein.
The integrator
606
can variably change characteristics thereof with an arbitrary frequency range, and, integrating the angular velocity data from the high-pass filter
605
, outputs the result of integration as angular displacement data.
The pan/tilt discrimination circuit
607
executes panning control by discriminating panning/tilting based on the angular velocity data from the A/D converter
604
and the angular displacement data from the integrator
606
.
More specifically, if the angular velocity data is at least equal to a predetermined threshold value, or if it is less than the predetermined threshold value but the angular displacement data (result of integration) is at least equal to a predetermined threshold value, a panning or tilting state is identified and the panning control is executed. In such panning control, the low range cut-off frequency of the high-pass filter
605
is shifted to a higher frequency, whereby a vibration correcting system in an image correction device
610
does not respond to lower frequencies. Also the time constant employed in the integrating operation of the integrator
605
is shifted to a shorter time, whereby the vibration correcting position of the image correcting circuit
610
is gradually shifted toward the center of a movable range and the angular displacement data outputted from the integrator
606
gradually approached a reference value (a value to be assumed in the absence of vibration).
In other situations, the panning or tilting is identified to have been completed, and the low range cut-off frequency of the high-pass filter
605
is shifted to a lower frequency and the time constant employed in the integrating operation of the integrator
606
is shifted to a longer time. Thus the low range cut-off frequency of the high-pass filter
605
and the time constant employed in the integrating operation of the integrator
606
are returned to the original state, and the panning control is terminated.
A digital/analog (D/A) converter
608
converts the angular displacement data from the integrator
606
into an analog value.
A driving circuit
609
drives the image correction device
610
based on the analog angular displacement data outputted from the D/A converter
608
.
The image correction device
610
is provided with an optical vibration correcting unit employing, for example a variable angle prism, and varies the vertical angle of the variable angle prism according to the drive by the drive circuit
609
, thereby optically correcting the vibration generated in the picked-up image.
As explained in the foregoing, the vibration correcting function
600
is adapted to detect the vibration in the apparatus by the angular velocity detection sensor
601
employing for example the vibration gyro, and to optically correct the vibration in the picked-up image based on the result of such detection.
However, the conventional vibration correcting functions such as that
600
have been associated with the following drawbacks:
(1) In a configuration for correcting the vibration in the picked-up image, utilizing the output signal of the vibration gyro or the like detecting the angular velocity, the error in the correction of the picked-up image increases with an increase in the magnification of the image pickup lens, namely when the image pickup lens is operated at a telephoto side.
The error in the correction of the picked-up image indicates insufficient or excessive correction in the vibration correction system with respect to the vibration amount in the main body of the apparatus. The amount of correction error on the image pickup plane increases with an increase in the focal length of the optical system of the image pickup apparatus, which results in an increase in the image magnification.
(2) On the other hand, there is proposed a video camera with an interchangeable lens system similar to the conventional still camera, in order to widen the image pickup applications of the video camera.
In such a video camera, the interchangeable lens system allows one to easily attach a lens of high magnification, since such a high-magnification lens or an extender can be detachably mounted.
Consequently, the above-described correction error becomes larger in the image pickup apparatus of the interchangeable lens system such as the video camera, in comparison with the image pickup apparatus with the fixed lens.
(3) In particular, in the angular velocity detecting sensor utilizing the vibration gyro, the detection characteristics thereof deteriorate in a low frequency region less than 1 Hz. Consequently, in such low frequency region, the above-described correction error increases evidently, showing an insufficient correction in the low frequency region and leading to deterioration of the image quality.
In order to solve these drawbacks, there is proposed a vibration correcting function with improved correcting performance, by providing a circuit for detecting the remnant or insufficient vibration in the picked-up image, in addition to the angular velocity detection sensor employing for example the vibration gyro.
For example, as shown in
FIG. 12
, such vibration correction function
700
is provided, in addition to the components
601
-
610
of the vibration correction function
600
shown in
FIG. 11
, with a camera signal processing circuit
701
for generating a video signal for example of the NTSC format from the image information obtained from the image pickup e
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Garber Wendy R.
Villecco John M
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