Television – Camera – system and detail – Solid-state image sensor
Utility Patent
1998-08-25
2001-01-02
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Solid-state image sensor
C348S321000, C348S315000, C348S280000, C348S283000, C348S272000
Utility Patent
active
06169577
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a color CCD solid-state image pickup device comprising pixels arrayed in a matrix, vertical shift registers provided in correspondence with vertical columns of pixels for transferring signal charges from the pixels in the vertical direction and a color filter array of a kind such that it is not possible to mix pixels adjacent in the column direction.
The realization of high-resolution in solid-state image pickup devices is made possible by increasing pixel numbers, and to this end efforts have been made to increase pixel numbers; however, pixel number increases made hitherto have been increases in horizontal direction pixel numbers, and efforts have not been made to raise vertical direction pixel numbers. The reason for this is that vertical direction pixel numbers have been prescribed by television broadcast systems and it has been considered that there is no benefit in increasing pixel numbers against this prescription. By the same token, it is possible to raise horizontal direction resolution by increasing horizontal direction pixel numbers irrespective of television systems. Thus, it has been considered that for reasons related to television systems there is no meaning in increasing vertical direction pixel numbers it has not been possible to raise vertical direction resolution. As a result the problem has arisen that vertical resolution has become relatively low compared to horizontal resolution, and this unbalance is marked.
As one measure for resolving this unbalance it has been proposed that vertical resolution be doubled. One such proposal has been made in “A ½-inch, 900,000-Pixel IT-CCD Image Pickup Device”, ITE '94: 1994 ITE Annual Convention pp 475-476.
In this color CCD solid-state image pickup device the vertical number of pixels is 1000, about twice what it has been hitherto, and the horizontal number of pixels is made 850 to make a ½-inch, 900,000-pixel device of vertical resolution 450 TV lines and horizontal resolution 530 TV lines wherein 8-phase CCD registers are used for the vertical transfer parts. The color filter array of this device is as shown in FIG.
10
.
However, in the color CCD solid-state image pickup device described above wherein the vertical number of pixels is approximately twice what it has been in the past, as shown in
FIG. 10
, green G color filters are disposed in a certain pixel row (for example the 2Kth row), red R/blue B color filters are disposed in the row adjacent thereto on one side thereof (for example the 2K+1th row) and blue B/red R color filters are disposed in the row adjacent thereto on the other side (for example the 2K−1th row). Therefore, the array of the color filters, when seen in the column direction, has a green G/red R/green G/Blue B cycle of four pixels.
To interlace this color CCD solid-state image pickup device and make it compatible with a television system, as shown in
FIG. 10
, an operation, wherein in a certain field (for example a first field) signals of the pixels of the green G filters of the 4Kth row and the red R/blue B pixels of the 4K+1th row are read out and in the next field (a second field) signals of pixels of the green G filters of the 4K+2th row and signals of the pixels of the blue B/red R color filters of the 4K+3th row are read out, is carried out. A signal corresponding to one scanning line of a television signal is then synthesized from signals of the green G/red R/blue B of the 2Kth row and the 2K+1th row.
Therefore, if the pixels of the green G color filters and the red R/blue B color filters are looked at separately, this is equivalent to carrying out so-called frame read-out of pixels of green G filters (or pixels of red R/blue B filters) of 500 rows.
However, it has been well known that in frame read-out there is the problem that when the accumulation time of the pixels is made one frame period after imaging occurs and when it is made one field period the sensitivity is halved, and there is this kind of problem in the kind of related art color CCD solid-state image pickup device shown in
FIG. 10
also.
In ordinary color CCD solid-state image pickup devices, this problem associated with frame read-out can be avoided by employing a field read-out method, and in practice that is what has been done.
However, in the color CCD solid-state image pickup device shown in
FIG. 10
, because it is not possible to employ a field read-out method, it is not possible to avoid the problems associated with the frame method. The reason for this is that because in the read-out, adjacent pixels (for example those of the Kth row and those of the K+1th row) are mixed, the problem arises that mixing of green G and red R signals and mixing of green G and blue B signals occurs.
SUMMARY OF THE INVENTION
Accordingly, the present inventors undertook to carry out amelioration of frame afterimaging or improvement of sensitivity also in a color CCD solid-state image pickup device having a color filter array of a kind with which it is not possible to mix pixels adjacent to each other in the column direction, i.e. in a color CCD solid-state image pickup device with which it is not possible to employ a related art ordinary field read-out method, and arrived at making the present invention as a result of carrying out extensive research toward the realization of this.
An object of the invention is to carry out amelioration of frame afterimaging or improvement of sensitivity in a color CCD solid-state image pickup device having a color filter array with which it is not possible to mix pixels adjacent to each other in the column direction.
A color CCD solid-state image pickup device according to one embodiment of this invention is a color CCD solid-state image pickup device wherein even rows and odd rows of pixels arrayed in a matrix respectively have the same color filter arrays and is characterized in that signal charges of light-receiving parts in pixels in a Kth row (K being a positive integer) and signal charges of light-receiving parts of pixels in either of the K±2th rows are mixed and vertically transferred in vertical shift registers.
With such a color CCD solid-state image pickup device according to the invention, because even rows and odd rows of pixels respectively are the same, color mixing does not occur when they are mixed and field read-out by mixing and transferring signal charges of pixels of the Kth row and the K+2th row or mixing and transferring signal charges of pixels of the Kth row and the K−2th row becomes possible. As a result, because it is possible to handle interlacing with the color CCD solid-state image pickup device itself, it is possible to avoid the problem associated with frame read-out methods that when the signal accumulation time is made one frame period frame afterimaging occurs and when it is made one field period sensitivity is halved.
Of course, when it is not necessary to conform to a television system, by read out pixels without performing the above-mentioned mixing it is possible to reproduce images having superior resolution in the vertical direction.
In an embodiment of the invention, a color CCD solid-state image pickup device comprises pixels arrayed in a matrix, vertical shift registers provided in correspondence with vertical columns of pixels for transferring signal charges from said pixels in the vertical direction and a color filter array of a kind such that it is not possible to mix pixels adjacent in the column direction, wherein even rows and odd rows of said pixels arrayed in a matrix respectively have the same color filter arrays; and signal charges of light-receiving parts in pixels of a Kth row (K being a positive integer) and signal charges of light-receiving parts in pixels of either of the K±2th rows are mixed and vertically transferred in said vertical shift registers.
In an embodiment of the invention, a color CCD solid-state image pickup device comprises pixels arrayed in a matrix, vertical shift registers provided in corres
Garber Wendy
Sonnenschein Nath & Rosenthal
Sony Corporation
Wilson Jacqueline
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