Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1999-08-18
2001-06-19
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S224100, C348S249000, C348S273000, C348S279000
Reexamination Certificate
active
06249314
ABSTRACT:
The entire disclosure of U.S. patent application Ser. No. 08/779,333, filed Jan. 6, 1997 is expressly incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solid-state imaging apparatus having a solid-state imaging device and a signal processing circuit, used in a video camera and the like and a method for driving the solid-state imaging device.
2. Description of the Related Art
Recently, solid-state imaging devices and signal processing circuits used for such solid-state imaging devices has been improved in performance and are in use in a video camera for consumer use.
A conventional solid-state imaging device and a signal processing circuit used for such a solid-state imaging device described in Japanese Laid-Open Patent Publication No. 2-87685 will be described with reference to FIG.
18
.
Such a conventional solid-state imaging device includes photoelectric converting sections arranged two dimensionally and a vertical charge transfer section for vertically transferring charges which are output by the photoelectric converting sections. A plurality of reading operations are performed within a period in which images corresponding to one image plane are formed, and the charges which are output are mixed in the vertical charge transfer section. The vertical charge transfer section outputs the result.
For example, the two reading operations are performed within the above-described period. A charge Q
1
read in the first reading operation is accumulated in time duration t
1
, and a charge Q
2
read in the second reading operation is accumulated in time duration t
2
, which is different from time duration t
1
.
FIG. 18
illustrates the photoelectric converting characteristic of the conventional solid-state imaging device. In
FIG. 18
, the vertical axis represents the intensity of light, and the horizontal axis represents the level of the voltage obtained by converting the quantity of the output charge. The solid line indicates such a characteristic of the charge Q
1
, and the dashed line indicates such a characteristic of the charge Q
2
. The chain line represents such a characteristic of a charge Q
3
obtained as a result of the mixture of the charges Q
1
and Q
2
. As is illustrated in
FIG. 18
, the voltage based on the charge Q
1
which is output in the first reading operation reaches a saturation level of the photoelectric converting section when the intensity of light becomes B. The voltage based on the charge Q
2
which is output in the second reading operation reaches a saturation level of the photoelectric converting section when the intensity of light becomes D. The charge Q
2
provides a wide dynamic range, but provides a low S/N ratio when the intensity of light is low due to the low signal level thereof. The charge Q
1
provides a narrow dynamic range, but provides a high S/N ratio due to the high signal level thereof. Thus, the charge Q
3
provides a wide dynamic range and a high S/N ratio even if the intensity of light is low.
A solid-state imaging apparatus having the above-described structure has drawbacks. Specifically, the saturation levels of the photoelectric converting sections corresponding to different pixels are not uniform. Thus, the knee point of the charge Q
3
at which the curve representing the photoelectric converting characteristic turns drastically is different among different pixels. Such non-uniformity is represented as noise having a fixed pattern in an area of a video image having a high luminance, which significantly deteriorates the quality of the image.
Moreover, in the case where a plurality of color filters having different spectroscopic characteristics are provided in order to display a color image by a single solid-state imaging apparatus, color separation cannot be done due to the photoelectric converting characteristic having a knee point.
SUMMARY OF THE INVENTION
A method for driving a solid-state imaging device is provided. The solid-state imaging device includes a plurality of photoelectric converting sections arranged two dimensionally and respectively corresponding to a plurality of pixels, and a vertical charge transfer section for vertically transferring a charge read from each of the photoelectric converting sections. The method of the invention includes the steps of: performing a plurality of reading operations within a time duration for scanning an image for one image plane, thereby reading charges accumulated in the photoelectric converting sections to the vertical charge transfer section; and transferring the charges read from the photoelectric converting sections through the vertical charge transfer section separately for each of the reading operations.
According to another aspect of the invention, a solid-state imaging apparatus is provided. The solid-state imaging apparatus includes a solid-state imaging device and a signal processing circuit. The solid-state imaging device includes: a plurality of photoelectric converting sections provided with color filters having different spectroscopic characteristics, and each converting light incident thereon into a charge and accumulating the charge, and a plurality of vertical charge transfer sections for vertically transferring the charge read from each of the photoelectric converting sections. A plurality of reading operations to read the charges accumulated in the photoelectric converting sections to the plurality of the vertical charge transfer sections are performed within a time duration for scanning an image for one image plane, and the charges read from the photoelectric converting sections are transferred through the vertical charge transfer section separately for each of the reading operations. The signal processing circuit including: a plurality of color separation circuits each for performing color separation of signals based on the charges read by the plurality of reading operations and transferred separately; and a synthesis circuit for synthesizing the signals sent by the color separation circuits and outputting the resultant signal.
In one embodiment of the invention, the charges from fewer than all the photoelectric converting sections are read in at least one of the plurality of reading operations.
In another embodiment of the invention, the charges from all the photoelectric converting sections are read in each of the plurality of the reading operations.
In still another embodiment of the invention, the charges from at least two adjacent photoelectric converting sections in each of the plurality of reading operations are mixed together in the vertical charge transfer section.
In still another embodiment of the invention, the charges from at least two adjacent photoelectric converting sections in at least one of the plurality of reading operations are mixed together in the vertical charge transfer section, and the charges read in the remaining reading operations are vertically transferred with no mixture.
In still another embodiment of the invention, the photoelectric converting sections are provided with color filters having different spectroscopic characteristics from one another.
In still another embodiment of the invention, the image for one image plane is scanned within one field in a television scanning system.
In still another embodiment of the invention, the solid-state imaging device is irradiated by light for different time durations for the plurality of reading operations.
In still another embodiment of the invention, the plurality of reading operations are performed within a vertical blanking period in a television scanning system.
According to still another aspect of the invention, a solid-state imaging apparatus is provided. The solid-state imaging apparatus includes a solid-state imaging device and a signal processing circuit. The solid-state imaging device includes: a plurality of photoelectric converting sections provided with color filters having different spectroscopic characteristics, and each converting light incident thereon into a charge and accumulating the charge, an
Fujii Toshiya
Komobuchi Hiroyoshi
Matsuda Yuji
Yamamoto Yasutoshi
Yoneyama Masayuki
Garber Wendy R.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
Vu Ngoc-Yen
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