Television – Camera – system and detail – With single image scanning device supplying plural color...
Utility Patent
1997-06-17
2001-01-02
Ho, Tuan (Department: 2712)
Television
Camera, system and detail
With single image scanning device supplying plural color...
C358S514000
Utility Patent
active
06169576
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a solid state image sensing device, a color linear image sensor, and a method for controlling storage of signal charges in a color linear image sensor.
Hitherto, as a picture input element of a color scanner and a color copy machine, three-line CCD linear image sensors have been widely used. An example of such a linear image sensor will now be described with reference to FIG.
8
.
FIG. 8
is a model view showing outline of the structure of a three-line CCD linear image sensor. Photosensitive pixel trains
1
1
,
1
2
,
1
3
arranged in parallel to each other produce a group of signal charges corresponding to one scanning which correspond to light quantity of picture image projected through optical system (not shown). Above the respective photosensitive pixel trains, different color filters are formed. For example, red (R) filter is formed above the photosensitive pixel train
1
1
, green (G) filter is formed above the photosensitive pixel train
1
2
, and blue (B) filter is formed above the photosensitive pixel train
1
3
. As a result, the red component, the green component and the blue component of image are respectively taken out from the photosensitive pixel trains
1
1
,
1
2
,
1
3
. As stated above, the respective photosensitive pixel trains produce outputs of any colors of R, G, B with respect to the image corresponding to
1
line of scanning.
Moreover, CCD registers
3
1
-
3
3
for transferring signal charges produced are respectively disposed in parallel to corresponding photosensitive pixel trains
1
1
-
1
3
, and shift sections
2
1
-
2
3
for carrying out shift operation of signal charges from the photosensitive pixel trains to the CCD registers are respectively provided between the photosensitive pixel trains and the CCD registers corresponding to each other.
At the front end portions in the transfer direction of the respective CCD registers
3
1
-
3
3
, there are provided amplifiers
4
1
-
4
3
for converting output charges of the CCD registers
3
1
-
3
3
into electric signals to output them as picture signals of R, G, B.
In such a configuration, when two-dimensional image is projected onto photosensitive pixel trains
1
1
-
1
3
by scanning of optical system (not shown) or movement of object to be read such as manuscript, etc., signal charges are stored into photosensitive pixels of the respective photosensitive pixel trains. After a predetermined storage time, the signal charges stored in the respective photosensitive pixels of the photosensitive pixel trains are transferred to the CCD registers
3
1
-
3
3
by the shift sections
2
1
-
2
3
, and are sequentially transferred within the CCD registers
3
1
-
3
3
. The signals thus transferred are outputted from the amplifiers
4
1
-
4
3
. Such a series of shift, transfer and output operations are carried out in synchronism with a clock signal delivered from control section (not shown) and transfer pulse generated on the basis of this clock signal. A fixed operation is repeated every predetermined time corresponding to
1
line of scanning.
In the three-line sensor having RGB output constituted as described above, since these three lines respectively include the photosensitive pixel trains, the shift sections and the CCD registers, size between pixel trains in the subscanning direction (the direction perpendicular to the photosensitive pixel train) is large, and times until respective line sensors reach the same position of image are different. For this reason, it is necessary to adjust read timings from respective lines.
Namely, since three signals of R picture signal, G picture signal and B picture signal of color image to be obtained are required to take the same position on the time axis, an approach is employed for allowing positions on the time axis of respective picture signals to be in correspondence with each other to sequentially store respective picture signals into image memories to adjust read-out timings from the respective image memories to thereby allow line information of RGB picture signals to be in correspondence with each other.
As stated above, in the three-line CCD sensor constituted as shown in
FIG. 8
, in order to correct positional differences between photosensitive pixel trains, memories are required at the system side for carrying out image processing. In addition, in order to carry out correction of broad range, the memory capacities thereof were required to be extremely large.
In recent years, there has been proposed a configuration of the line proximity type in which the distances between respective photosensitive pixel trains are caused to be narrow in order to reduce the memory capacity.
FIG. 9
is a model view showing such an example.
In
FIG. 9
, the same reference numerals are respectively given to the portions corresponding to those of
FIG. 8
, and explanation of such portions will be omitted. In this configuration, photosensitive pixel trains
1
1
-
1
3
are disposed in a manner adjacent to each other and shift section
2
2
is disposed between the second photosensitive pixel train
1
2
and the third photosensitive pixel train
1
3
. On these photosensitive pixel trains
1
1
,
1
2
,
1
3
, color filters of red, green and blue, etc. are respectively formed. In this example, drive voltage pulses, etc. are suitably applied to the respective shift sections and the respective CCD registers from control section (not shown).
The read operation of the device shown in
FIG. 9
will now be described with reference to the signal timing diagram of FIG.
10
.
Initially, at time T
1
, drive voltage pulse V
21
is applied to the shift section
2
1
. As a result, signal charges corresponding to one line produced at the photosensitive pixel train
1
1
, are transferred to the CCD register
3
1
through the shift section
2
1
. At time T
2
, drive voltage pulse V
23
is applied to the shift section
2
3
. As a result, signal charges corresponding to one line produced at the photosensitive pixel train
1
3
are transferred to the CCD register
3
2
through the shift section
2
3
. At time T
3
, drive voltage pulse V
24
is applied to the shift section
2
4
. As a result, signal charges of the CCD register
3
2
are transferred to the CCD register
3
3
through the shift section
2
4
. At time T
4
, drive voltage pulse V
22
is applied to the shift section
2
2
. As a result, signal charges corresponding to one line of the photosensitive pixel train
1
2
are transferred to the photosensitive pixel train
1
3
through the shift section
2
2
. At time T
5
, drive voltage pulse V
23
is applied to the shift section
2
3
. As a result, the signal charges corresponding to one line which have been transferred to the photosensitive pixel train
1
3
are transferred to the CCD register
3
2
through the shift section
2
3
.
The signal charges corresponding one line respectively held at the CCD registers
3
1
-
3
3
are transferred to amplifiers (output sections)
4
1
,
4
2
and
4
3
at the same time or suitably. Thus, respective picture signals of R, G and B are outputted.
In accordance with the configuration shown in
FIG. 9
, as compared to the conventional configuration in which CCD registers are disposed between respective photosensitive pixel trains, because it is sufficient to provide only the shift section
2
2
between three photosensitive pixel trains, the distances between respective photosensitive pixel trains can be reduced. Accordingly, the memory capacity used for adjustment of positions on the time axis of respective picture signals of R, G and B produced resulting from the fact that positions of the photosensitive pixel trains of R, G and B are spaced to each other can be reduced.
Meanwhile, there are proposed image sensors adapted to have ability of carrying out enlargement/contraction or change in reading accuracy of image to be read. In such image sensors, there are instances where the resolution in the sub-scanning direction is switched in correspondence with such a change.
However, in typical three-line sensors, the dist
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Ho Tuan
Kabushiki Kaisha Toshiba
Nguyen Luong
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