Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
1999-05-03
2004-09-14
Garber, Wendy R. (Department: 2712)
Television
Camera, system and detail
Solid-state image sensor
C348S265000, C348S324000, C438S060000, C438S075000, C257S229000, C257S232000
Reexamination Certificate
active
06791614
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color linear image sensor device with a shutter function for charges generated by a photodetector, and a method of manufacturing such a color linear image sensor device.
2. Description of the Related Art
Color linear image sensors are semiconductor devices having a plurality of parallel CCD linear image sensors disposed on a semiconductor substrate and having a charge transfer function. CCD linear image sensors comprise arrays of photodetectors with color filters of different colors (e.g., three color filters of the colors GREEN, BLUE, RED) mounted thereon.
Color linear image sensors have functions of converting incident light into charges and of successively outputting the charges, and are being widely used as a vital device in color scanners and color copying machines.
In actual color scanners and color copying machines, the color linear image sensor is mechanically scanned in a direction (feed direction) perpendicular to the direction (main scanning direction) of the arrays of photodetectors of the color linear image sensor for generating color information of an image in given positions on a subject. Color information of the image in given positions on the subject is produced for each of the colors using line outputs
1
,
2
,
3
, . . . .
FIG. 1
is a view showing an overall arrangement of a conventional color linear image sensor. The color linear image sensor shown in
FIG. 1
has no charge control function (shutter function).
As shown in
FIG. 1
, the conventional color linear image sensor comprises photodetector circuits
1001
a
-
1001
c
have R, G, B color filters (not shown) mounted thereon for photoelectrically converting received light into charges, charge read circuits
1002
a
-
1002
c
for reading the charges generated and stored by the photodetector circuits
1001
a
-
1001
c
, and charge transfer circuits
1003
a
-
1003
c
for transferring the charges read by the charge read circuits
1002
a
-
1002
c.
The charge transfer circuits
1003
a
-
1003
c
usually comprise CCD shift registers that are driven by two-phase drive clocks ø
1
, ø
2
. The two-phase drive clocks ø
1
, ø
2
are supplied from pulse lines L
1001
a
-L
1001
c
, L
1002
a
L
1002
c
that are disposed closely to the charge transfer circuits
1003
a
-
1003
c
. The charges transferred by the charge transfer circuits
1003
a
-
1003
c
, which are actually formed by floating diffused regions, are outputted from output circuits
1004
a
-
1004
c
each comprising a charge detector for converting charges into voltages and an analog circuit including a source follower, an inverter, etc.
FIG. 2
is a view showing a detailed structure of the conventional color linear image sensor shown in FIG.
1
. In
FIG. 2
, a lower figure section is an enlarged view of an area X
4
indicated by the dotted lines in an upper figure section.
In
FIG. 2
, the color linear image sensor comprises polycrystalline silicon electrodes
1014
a
,
1014
b
indicated by the dot-and-dash lines and dotted lines, device separating areas
1017
indicated by the thin dotted lines, contacts
1006
,
1007
,
1009
indicated as small squares, and aluminum interconnections
1005
,
1008
,
1010
indicated by the solid lines.
FIG. 3A
is a timing chart representing a taiming of timing the conventional color linear image sensor shown in FIG.
1
.
In
FIG. 3A
, charges from the photodetector circuits
1001
a
-
1001
c
are stored while pulses øTGa, øTGb, øTGc are in low level (storage times tTGa, tTGb, tTGc), and read into the charge transfer circuits
1003
a
-
1003
c
while the pulses øTGa, øTGb, øTGc are in high level. The outputs are line outputs, respectively, representing successions of outputs from all pixels ranging from the first pixel to the last pixel in the photodetector circuits
1001
a
-
1001
c
. The storage times for the photodetector circuits
1001
a
-
1001
c
are equal to each other (tTGa=tTGb=tTGc).
If average voltages of all the pixels of the respective line outputs, from a reference level (no incident light applied), are represented by Vsiga, Vsigb, Vsigc, then depending on the sensitivity of the photodetector circuits
1001
a
-
1001
c
, the relation of these average voltages are represented as Vsiga>Vsigb>Vsigc.
FIG. 3B
is a timing chart representing a timing of driving the conventional color linear image sensor shown in
FIG. 1
by changing the storage times for charges with respect to the respective colors, rather than changing the amount of exposure according to the amount of incident light.
As shown in
FIG. 3B
, the storage times tTGa, tTGb, tTGc for the respective colors are adjusted to yield saturated amounts of exposure SEG, SER, SEB, providing the same saturated output voltages Vsiga, Vsigb, Vsigc.
Another conventional color linear image sensor is disclosed in U.S. Pat. No. 5,105,264. The disclosed color linear image sensor is shown in FIG.
4
. In the disclosed color linear image sensor, each of photodetector circuits has a shutter function.
The color linear image sensor shown in
FIG. 4
comprises shutter gates
1015
a
-
1015
c
, shutter drains
1016
a
-
1016
c
, photodetector circuits
1001
a
-
1001
c
for photoelectrically converting received light into charges, charge read circuits
1002
a
-
1002
c
for reading the stored charges, charge transfer circuits
1003
a
-
1003
c
for transferring the charges read by the charge read circuits
1002
a
-
1002
c
, and output circuits
1004
a
-
1004
c
for outputting the charges transferred by the charge transfer circuits
1003
a
-
1003
c.
Two-phase drive clocks ø
1
, ø
2
for driving the charge transfer circuits
1003
a
-
1003
c
are supplied from pulse lines L
1001
a
-L
1001
c
, L
1002
a
-L
1002
c
that are disposed closely to the charge transfer circuits
1003
a
1003
c.
The shutter gates
1015
a
-
1015
c
and the shutter drains
1016
a
-
1016
c
are disposed on the opposite side of the photodetector circuits
1001
a
-
1001
c
, which appropriately changes the pulse width supplied to the shutter gates
1015
a
-
1015
c
while pulses øTGa, øTGb, øTGc applied to the charge read circuits
1002
a
-
1002
c
are in low level, enabling a production of the appropriate amounts of exposure with respect to the three colors R, G, B.
The shutter gates
1015
a
-
1015
c
and shutter drains
1016
a
-
1016
c
are also provided in the conventional color linear image sensor shown in FIG.
4
.
FIG. 5
is a timing chart representing a timing of driving the conventional color linear image sensor is shown in FIG.
4
.
As shown in
FIG. 5
, the storage times tTGa, tTGb, tTGc for the respective colors are equal to each other (tTGa=tTGb=tTGc), so that the line outputs from the respective three colors can be outputted in synchronism with each other. Even if the photodetector circuits
1001
a
-
1001
c
have different sensitivity, adjustment of the width of pulses øSta, øSTb, øSTc supplied to shutter gates
1015
a
-
1015
c
affords the same voltage (Vsiga=Vsigb=Vsigc) for the respective three colors.
The same voltage can be produced for the respective three colors for the following reasons: Since pulses øTGa-øTGc applied to the charge read circuits
1002
a
-
1002
c
are low level While pulses øSTa-øSTc supplied to the shutter gates
1015
a
-
1015
c
are high level, and charges stored in the photodetector circuits
1001
a
-
1001
c
are drained into the shutter drains
1016
a
-
1016
c
, and hence are reduced charges in the photodetector circuits
1001
a
-
1001
c
to zero level. When the pulses øSTa-øSTc supplied to the shutter gates
1015
a
-
1015
c
then become low level, an accumulation of charges starts again.
The substantial charge storage times for the signal outputs of the colors R, G, B are thus represented by tSTa, tSTb, tSTc, respectively. Based on these storage times tSTa, tSTb, tSTc, it is possible to establish appropriate amounts of exposure for the signal outputs of the colors R, G, B, and to cause the same saturated output voltage for the three colors to be out
Garber Wendy R.
Misleh Justin
NEC Electronics Corporation
Young & Thompson
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