Television – Camera – system and detail – Optics
Reexamination Certificate
1999-11-03
2004-03-23
Moe, Aung (Department: 2612)
Television
Camera, system and detail
Optics
C348S221100
Reexamination Certificate
active
06710808
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image sensing apparatus for sensing a still image and/or moving image.
2. Description of the Related Art
Conventionally, image sensing apparatuses such as electronic cameras and the like, which record/play back still images and moving images sensed by a solid-state image sensing element such as a CCD or the like using memory cards having solid-state memory elements as recording media, have already been commercially available.
Since these electronic cameras have an auto-focusing (AF) function and auto-exposure (AE) function, the electronic camera user can easily take a picture.
Especially, in servo AF operation that keeps focusing on an object by following its movement, an in-focus is maintained by following the object movement, and exposure measurement (AE) is also done by following the object movement, thus updating the aperture value (Av value) and shutter speed (Tv value) as needed.
When the electronic camera further has an AE lock function, if the exposure measurement value of the object is fixed and inhibited from being updated, auto-focusing (AF) and auto-exposure (AE) can be independently controlled.
On the other hand, when an image is sensed using a solid-state image sensing element such as a CCD or the like, a dark noise correction process can be done by computations using dark image data which is read out after charge accumulation in the same manner as in actual image sensing while the image sensing element is not exposed, and actually sensed image data which is read out after charge accumulation while the image sensing element is exposed.
With this process, sensed image data can be corrected for image quality deterioration such as pixel omission or the like caused by dark current noise produced by the image sensing element and small scratches unique to the image sensing element, thus obtaining a high-quality sensed image.
Especially, since dark current noise increases with increasing charge accumulation time and temperature rise of the image sensing element, if exposure for a long period of time (seconds) or at high temperature is done, a great image quality improvement effect can be obtained, and the dark noise correction process is a function useful for the electronic camera users.
The charge accumulation time must be determined in correspondence with the shutter speed (Tv value) obtained by exposure measurement.
In the servo AF operation that keeps focusing on an object by following its movement, since the exposure measurement value must be updated every time the object luminance has changed, the shutter speed is determined after the exposure value is settled upon depression of the shutter switch, and the CCD charge accumulation time is determined accordingly. For this reason, after the shutter switch is pressed, actual image sensing and sensing of a dark image are done.
For this reason, when dark image data is sensed after actual image sensing, the interval between the first and second frames is prolonged by the dark image sensing time, and constant image sensing frame intervals cannot be set.
On the other hand, when actual image sensing is done after dark image data is sensed, the shutter release time lag becomes large since actual image sensing cannot be started until the dark image data capture process is completed, thus missing a shutter chance.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide an apparatus, which comprises an image sensing device, an image sensing time fixing instruction device for instructing to fix an image sensing time so as to inhibit the image sensing time of the image sensing device from changing in each image sensing, and a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device having a first mode for making the image sensing device perform the first image sensing operation and then the second image sensing operation, and a second mode for making the image sensing device perform the second image sensing operation and then the first image sensing operation, and the image processing device operating in the second mode if the image sensing time fixing instruction device instructs to fix the image sensing time, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.
Another aspect of the present invention is to provide an apparatus, which comprises an image sensing device, an image sensing time fixing instruction device for instructing to fix an image sensing time so as to inhibit the image sensing time of the image sensing device from changing in each image sensing, an exposure instruction device for issuing an exposure preparation instruction at a first stroke position of a shutter release member, and issuing an exposure start instruction at a second stroke position of the shutter release member, and a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation, the signal processing device performing the second image sensing operation in response to the exposure preparation instruction issued by the exposure instruction device if the image sensing time fixing instruction device instructs to fix the image sensing time, thereby preventing a shutter chance from being missed, and setting constant image sensing frame intervals.
REFERENCES:
patent: 5327193 (1994-07-01), Date et al.
patent: 6084634 (2000-07-01), Inagaki et al.
patent: 2002/0008766 (2002-01-01), Tariki
patent: 2002/0186313 (2002-12-01), Kidono et al.
Moe Aung
Morgan & Finnegan , LLP
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