Television – Camera – system and detail – Optics
Reexamination Certificate
1997-11-25
2001-02-06
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Optics
C348S280000, C348S296000, C348S312000, C348S347000, C396S096000
Reexamination Certificate
active
06184933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to image pickup apparatus and, more particularly, to an apparatus which is suitably used in a so-called multi-element image pickup device which picks up an object image using a plurality of image pickup elements.
2. Related Background Art
A conventional video camera reproduces a picked-up image on a television screen. For this reason, the recording rate of the video camera is determined to be a predetermined value. For example, in the case of the NTSC system, 60 fields (frames) of images are recorded per second. More specifically, an exposure is performed in 1/60 sec, and an image signal is read out and recorded in the next 1/60 sec.
On the other hand, upon detection of the state of incident light for auto-focus (to be abbreviated as AF hereinafter) control, auto-exposure (to be abbreviated as AE hereinafter) control, and the like, a signal for a photographing operation is read out, and thereafter, required data is fed back from this signal to control the iris and the lens driving operation.
For example, photometry for the AE control is performed based on a signal obtained by averaging, by an integrator, a plurality of frames of (three to four frames) of signals, which are output from an image pickup element and are amplified by an amplifier. On the other hand, in the AF control, a high-frequency component of a signal of each field is extracted, and the lens is controlled to maximize the extracted component.
Japanese Laid-Open Patent Application No. 4-212577 discloses a technique for performing two or more AF scans per field period by setting the read-out range in the vertical direction to be a portion of a photographing screen including a distance measurement frame.
As described above, the video camera can control the iris and lens only after a signal exposed in one field period (1/60 sec) is read out for one field period. For this reason, since the video camera cannot quickly respond to an abrupt movement of an object or an abrupt change in brightness, the photographed image often becomes too dark or bright.
For the same reason as above, the focal point cannot often be adjusted to an object which moves abruptly. When a photographing light beam is split by, e.g., a prism, and is received by AE and AF sensors different from the image pickup element, the amount of light guided to the image pickup element for a photographing operation decreases, resulting in deterioration of image quality and an increase in cost.
In the technique proposed by Japanese Laid-Open Patent Application No. 4-212577, since a signal read out from the image pickup element corresponds to a portion of the screen, the signal cannot be used in a photographing operation. Therefore, in this case, since a photographing operation is started after the end of the AF operation, an image to be photographed cannot be confirmed during the AF operation, and the time required until the photographing operation is started is long, resulting in a large time lag.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide an image pickup device which can simultaneously perform an image pickup operation of an object image and detection of the state of incident light.
It is another object of the present invention to provide an image pickup device which can prevent an image in a finder from being interrupted during a photographing operation.
An image pickup device according to an embodiment of the present invention has a plurality of image pickup elements. An object image signal is generated on the basis of a signal output from at least one of these image pickup elements, and the state of incident light is detected on the basis of a signal from another image pickup element having substantially the same photographing region as that of the image pickup element used for generating the object image.
As another feature of the present invention, the image pickup element for generating the object image has an exposure amount different from the image pickup element used for detecting the state of incident light.
As still another feature of the present invention, the read-out time or read-out interval (or cycle) per frame of the image pickup element for generating the object image is different from that of the image pickup element used for detecting the state of incident light.
As still another feature of the present invention, the effective read-out range of the image pickup element for generating the object image is different from that of the image pickup element used for detecting the state of incident light.
As still another feature of the present invention, the image pickup device has a plurality of image pickup elements, and has a first mode for detecting the state of incident light on the basis of a signal from at least one of these image pickup elements, and a second mode for photographing an object image using at least two of the plurality of image pickup elements.
As still another feature of the present invention, the first and second modes are selected by single operation means.
Since the embodiment of the present invention has the above-mentioned technical means, generation of an object image and detection of the state of incident light can be simultaneously performed. Therefore, the state of incident light can be detected at the position and time of an image to be photographed which are independent from the read-out state of the image to be photographed such as the read-out range, read-out time or read out interval (or cycle) recording rate, and the like of the image to be photographed while photographing an image or while confirming an object as a finder image.
According to other features of the present invention, since the device has the first mode for detecting the state of incident light on the basis of a signal from at least one image pickup element and the second mode for photographing an object image using at least two image pickup elements, a case wherein the AE control, AF control, and the like are performed at high speed, a case wherein the recording capacity is to be reduced, and a case wherein an image is to be photographed with higher image quality can be desirably selected. In addition, the time lag upon switching from the first mode to the second mode can be reduced.
The above and other features and objects of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4599640 (1986-07-01), Dischert
patent: 4599653 (1986-07-01), Kimura
patent: 4843474 (1989-06-01), Suzuki
patent: 5081535 (1992-01-01), Kondo et al.
patent: 5307158 (1994-04-01), Tsuruta et al.
patent: 5363137 (1994-11-01), Suga et al.
patent: 5379069 (1995-01-01), Tani
patent: 5418564 (1995-05-01), Aoki et al.
patent: 5436660 (1995-07-01), Sakamoto
patent: 5515132 (1996-05-01), Iwasaki
patent: 5526048 (1996-06-01), Yamamoto
patent: 5589880 (1996-12-01), Tsukui
patent: 5619260 (1997-04-01), Miyadera
patent: 5914755 (1999-06-01), Ito et al.
patent: 4-3670 (1992-01-01), None
patent: 4-212577 (1992-08-01), None
Yoshihiro Fujita, et al., “An HDTV 2/3-inch CCD Hand-held Camera Employing Dual-green Spacially Offset Image Pickup Method,” J. Telev. Soc., vol. 47, No. 2, 1993 (with English Abstract).
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Garber Wendy
Vu Ngoc-Yen
LandOfFree
Image pickup apparatus wherein plural elements... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image pickup apparatus wherein plural elements..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image pickup apparatus wherein plural elements... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2558366