U.S. patent number RE32,492 [Application Number 06/878,631] was granted by the patent office on 1987-09-01 for solid-state color television camera device.
This patent grant is currently assigned to Tokyo Shibaura Denki Kabushiki Kaisha. Invention is credited to Yasuo Takemura.
United States Patent |
RE32,492 |
Takemura |
September 1, 1987 |
Solid-state color television camera device
Abstract
According to the invention, a photosensor array having a
plurality of photosensors are formed in horizontal and vertical
rows on a semiconductor substrate. Vertical charge transfer
electrodes are provided along the vertical rows of photosensors for
transferring the charges generated in the photosensors along the
vertical direction. Charge mixing means are provided, within the
substrate, for mixing the charges generated by the photosensors in
successive two horizontal rows of photosensors.
Inventors: |
Takemura; Yasuo (Tokyo,
JP) |
Assignee: |
Tokyo Shibaura Denki Kabushiki
Kaisha (Kawasaki, JP)
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Family
ID: |
13937545 |
Appl.
No.: |
06/878,631 |
Filed: |
June 26, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
380145 |
May 20, 1982 |
04460919 |
Jul 17, 1984 |
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Foreign Application Priority Data
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Jun 10, 1981 [JP] |
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56-88248 |
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Current U.S.
Class: |
348/277;
348/319 |
Current CPC
Class: |
H04N
9/04557 (20180801); H01L 27/14868 (20130101); H04N
9/0451 (20180801); H01L 27/14818 (20130101) |
Current International
Class: |
H04N
9/04 (20060101); H04N 009/07 () |
Field of
Search: |
;358/41,43,44,47,213 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Masinick; Michael A.
Attorney, Agent or Firm: Banner, Birch, McKie &
Beckett
Claims
I claim:
1. A solid-state color television camera device comprising:
a semiconductor substrate;
a photosensor array, formed on the substrate, having a plurality of
photosensors arranged in horizontal and vertical rows, each
photosensor generating a charge upon receipt of an image;
a vertical transfer means, positioned adjacent each vertical row of
photosensors and responsive to vertical transfer signals, for
receiving the charges generated by the adjacent photosensors and
transferring the charges to a horizontal transfer means;
a charge mixing means, coupled to said vertical transfer means, for
mixing the charges generated by the photosensors in two adjacent
horizontal rows;
a horizontal transfer means, positioned adjacent one end of each
vertical row of photosensors for receiving the charges transferred
by the vertical transfer means, and transferring them as an output
signal to an output terminal formed on the substrate;
a color filter array having a plurality of separate filter elements
arranged in horizontal and vertical rows, each of said elements
corresponding to a respective photosensor;
said color filter array comprising a plurality of unit filter
arrays, each unit consisting of 2.times.4 filter elements of yellow
(Ye), green (G), cyan (Cy) and white (W) colors.
2. A color television camera device according to claim 1, wherein
the white filter elements pass the red, green and blue colors, the
green filter elements pass the light of only the green color, the
yellow filter elements pass the light of only the red and green
colors, and the cyan filter element pass the light of only the
green and blue colors.
3. A television camera device of claim 2 wherein the output signal
of said horizontal transfer means comprises a first modulated color
signal representing the signal along one horizontal row of
photosensors and a second modulated color signal representing the
signal along an adjacent horizontal row,
said first modulated color signal comprising a signal modulated by
a first and second primary colors having different phases,
said second modulated color signal comprising a signal modulated by
a first and second primary colors having the same phases.
4. A television camera device according to claim 3 wherein said
first and second primary colors are red and blue, respectively.
5. A color television camera device according to claim 1 wherein
each vertical transfer means comprises a plurality of vertical
electrodes whereby two electrodes are provided for each
photosensor, and said charge mixing means includes a charge gating
electrode positioned between each photosensor and its corresponding
two vertical transfer electrodes and responsive to gate control
signals for gating and transferring the charge of from each
photosensor to one of its corresponding electrodes;
a gate pulse generating means, coupled to each charge gating
electrode, for producing said gate control signals for controlling
the transfer of charges from each photosensors to its corresponding
vertical transfer electrode before said vertical transfer signals
are applied to the vertical transfer electrodes during every field
scanning period of the television display system.
6. A television camera device according to claim 5 wherein said
charge gating electrode is integrally formed with said one
corresponding vertical transfer electrode.
7. A color television camera device according to claim 5 wherein
said vertical transfer signals are four phase clock signals and
said gate control signals are superimposed on said vertical
transfer signals at the beginning of each vertical transfer
period.
8. A color television camera device according to claim 5 wherein
each of said one corresponding vertical transfer electrodes is
connected to said gate pulse generating means, and said field
scanning period includes an odd scanning period and an even
scanning period;
wherein during said odd scanning period, said gate control signals
drive, during a first gating sequence, the charge gating electrodes
in odd horizontal rows together with each of said corresponding
vertical transfer electrodes to transfer the charge into said
corresponding vertical transfer electrode and then sequentially
into the transfer electrodes of the succeeding horizontal rows and,
during a second gating sequence, said gate control signals drive
the charge gating electrodes in the next adjacent horizontal rows
to transfer the charge from the next adjacent photosensor to one of
its corresponding vertical transfer electrodes at the same time the
charge from the preceding row has entered the corresponding
vertical transfer electrode of the next adjacent photosensor;
and
wherein during said even scanning period, said gate control signals
drive, during a first gating sequence, the charge gating electrodes
in even horizontal row together with each of said corresponding
vertical transfer electrodes to transfer the charge into said
corresponding vertical transfer electrodes and then sequentially
into the transfer electrodes of the succeeding horizontal rows and,
during a second gating sequence, said gate control signals drive
the charge gating electrodes in the next adjacent horizontal rows
to transfer the charge from the next adjacent photosensor to one of
its corresponding vertical transfer electrodes at the same time the
charge from the preceding row has entered the corresponding
vertical transfer electrode of the next adjacent photosensor.
9. A color television camera device according to claim 1 wherein
each vertical transfer means comprises a plurality of vertical
electrodes whereby two electrodes are provided for each photosensor
and each filter element,
whereby said charge mixing means mixes the charges in two adjacent
vertical electrodes, each of which is positioned under a different
filter element, by forming a potential well common to said two
adjacent electrodes.
10. A color television camera device according to claims 1, 5 or 9,
further comprising:
a first filter means coupled to said color image output signal for
extracting a luminance signal (Y);
a second filter means coupled to said color image output signal for
extracting low frequency components of the luminance signal
(Y);
a band pass filtering means coupled to said color image output
signal for extracting a modulated color signal;
a 1 H delay circuit coupled to said bandpass filtering means for
producing a 1 H delayed output signal;
a summing means for summing said modulated output signals with said
1 H delayed output signal to produce a modulated red color
signal;
a subtracting circuit for subtracting said modulated output signal
with said 1 H delayed output signal to produce a blue modulated
color signal;
a red signal demodulating means for demodulating said red modulated
color signal to obtain a red color signal;
a blue signal demodulating means for demodulating said blue
modulated color signal to obtain a blue color signal;
a color matrix means coupled to said blue and red signal
demodulating means for producing a green color signal; and, a color
encoder means for producing standard color television signals.
11. A color television camera device according to claim 9 wherein
said first filter means passes frequencies below approximately 3
MHz, said second filter means passes frequencies below
approximately 0.5 MHz and the band pass filter means passes
frequencies from approximately 3 MHz to 4 MHz. .Iadd.12. A
solid-state color television camera device comprising:
a semiconductor substrate;
a photosensor array, formed on the substrate, having a plurality of
photosensors arranged in horizontal and vertical rows, each
photosensor generating a charge upon receipt of an image;
a vertical transfer means, positioned adjacent each vertical row of
photosensors and responsive to vertical transfer signals, for
receiving the charges generated by the adjacent photosensors and
transferring the charges to a horizontal transfer means;
a charge mixing means, coupled to said vertical transfer means, for
mixing the charges generated by the photosensors in two adjacent
horizontal rows;
a horizontal transfer means, positioned adjacent one end of each
vertical row of photosensors for receiving the charges transferred
by the vertical transfer means, and transferring them as an output
signal to an output terminal formed on the substrate;
a color filter array having a plurality of separate filter elements
arranged in horizontal and vertical rows, each of said elements
corresponding to a respective photosensor;
said color filter array, comprising a plurality of unit filter
arrays, each unit consisting of 2.times.4 filter elements of yellow
(Ye), green (G), cyan (Cy) or white (W) colors and including at
least one element of the
yellow (Ye) and cyan (Cy) colors. .Iaddend. .Iadd.13. The color
television camera device of claim 12 wherein each of said unit
filter arrays consists of 2.times.4 filter elements of yellow (Ye),
cyan (Cy) and green (G). .Iaddend. .Iadd.14. The color television
camera device of claim 12 wherein each of said unit filter arrays
consists of 2.times.4 filter elements of yellow (Ye), cyan (Cy) and
white (W). .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a color television camera device which
uses a solid-state image pickup device. In particular, it relates
to a device using a solid-state pickup device whereby signals in
two successive horizontal lines are simultaneously read out during
every horizontal scanning period.
In conventional solid-state color image pickup devices, a color
filter array is provided on the surface of a photosensor array
formed in a semiconductor substrate. With the increasing need for
utilizing semiconductor image pickup devices, there existed a
problem of registration between the filter array and photosensor
array. The prior art has proposed to overcome this problem by
simultaneously reading out two successive lines of signals during
every horizontal scanning period; these lines of signals are then
processed to obtain the color signals (see Japan Patent Publication
No. 56-37756). The proposed device, however, has a complex
integrated structure for simultaneously reading out the two
successive lines of signals and is difficult and costly to
manufacture such a device.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved color image
pickup device utilizing simplified circuitry, whereby image signals
in successive two lines are simultaneously read out during every
horizontal scanning period.
It is another object of the invention to provide a novel color
filter array suitable for simultaneous reading out the image
signals in successive two lines with interlaced scanning.
According to the invention, a photosensor array having a plurality
of photosensors are formed in horizontal and vertical rows on a
semiconductor substrate. Vertical charge transfer electrodes are
provided along the vertical rows of photosensors for transferring
the charges generated in the photosensors along the vertical
direction. Charge mixing means are provided, within the substrate,
for mixing the charges generated by the photosensors in successive
two horizontal rows of photosensors.
In one embodiment utilizing the so-called interline transfer type
CCD, a charge gating electrode is provided between each photosensor
and the vertical transfer electrodes. This gating electrode gates,
transfers and permits mixing of, the charges generated in two
adjacent horizontal rows of photosensors at the beginning of the
vertical transfer period. A first gating electrode transfers the
charges along the first row of each row pair to the vertical
transfer electrode. As the charge of each first row is transferred
down the vertical transfer rows and reaches the second row of the
row pair, a second gating electrode transfers the charge of the
second row to the transfer means. This results in a mixing of the
charges of the first and second row.
A horizontal transfer means is provided for receiving the charges
transferred by the vertical transfer means and for horizontally
transferring the image signals to a signal processor which converts
these signals to standard color television signals. A color filter
array is provided on the surface of the solid-state image pickup
device. The color filter array has a plurality of filter elements,
each corresponding to a photosensor. Each filter element consists
of the following four different colors: yellow (Ye), green (G),
cyan (Cy) and white (W). In the color filter array, a unit array of
2.times.4 elements is repeated, horizontally and vertically. This
unit array is formed such that an output image signal obtained from
one horizontal photosensor row includes signals modulated by at
least a first and second primary colors with different phases and
having the same repetition cycle, while the output image signal
obtained from an adjacent horizontal photosensor row includes
signals modulated by at least the first and second primary colors
having the same phases and repetition cycle (see, e.g., FIG. 5:
L.sub.1, L.sub.2). The first and second colors are preferably R and
B, respectfully.
According to another embodiment of the invention, the so-called
frame transfer type CCD image pickup device is utilized. With this
device, during a storage time, mixing signals are applied to the
vertical transfer electrodes prior to .[.transfering.].
.Iadd.transferring .Iaddend.the charges to the storage area. More
specifically, the mixing signals drive two pairs of adjacent
vertical electrodes, corresponding to two adjacent filter elements.
One pair corresponds to one filter element and the other pair
corresponds to a different adjacent filter element. A potential
well is formed which is common to the two middle electrodes for
mixing the charges generated by the colors passing through the
different adjacent filter elements.
BRIEF DESCRIPTION OF THE DRAWINGS
A complete understanding of the present invention and of the above
and other objects thereof may be gained from a consideration of the
following detailed description of the specific illustrative
embodiments thereof presented hereinafter in connection with the
accompanying drawings, in which:
FIG. 1 schematically shows an embodiment of a CCD image pickup
device according to the invention;
FIG. 2 schematically shows a cross-sectional view of the CCD device
taken along a line 2--2 in FIG. 1;
FIG. 3 shows a portion of a color filter array incorporated in the
embodiments of the present invention;
FIG. 4 is a diagram for explaining the operation of the embodiment
of the invention shown in FIG. 1;
FIGS. 5(a)-5(d) are diagrams for explaining the processing of
signals in the embodiment of the invention shown in FIG. 1;
FIGS. .[.6a-6b.]. .Iadd.6(a)-6(b) .Iaddend.are diagrams of
waveforms of the vertical transfer drive signals utilized in the
embodiment of the present invention shown in FIG. 1;
FIGS. .[.7a-7b.]. .Iadd.7(a)-7(b) .Iaddend.schematically show the
gating and mixing process carried out in the embodiment of the
invention shown in FIG. 1;
FIG. 8 .[.shows.]. .Iadd.show .Iaddend.a block diagram of the
signal processing circuitry incorporated in the embodiments of the
invention;
FIGS. 9-14 .[.shows.]. .Iadd.show .Iaddend.different embodiments of
color filter arrays according to the invention;
FIG. 15 is a plan view of a further embodiment of the invention
shown in FIG. 1;
FIG. 16 schematically shows a cross sectional view taken along a
line 16--16 in FIG. 15;
FIG. 17 shows a plan view of CCD device according to another
embodiment of the invention;
FIG. 18 schematically shows a cross sectional view taken along a
line 18--18 in FIG. 17; and
FIG. 19 is a diagram of waveforms of the vertical drive signals
utilized in the embodiment shown in FIG. 17.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a plan view of a CCD color image pickup device made in
accordance with the present invention. A p-type silicon
semiconductor substrate 11 is provided on which a number of
photodiodes or photosensors 12 are formed on the surface thereof.
The photosensors 12 are arranged in a matrix pattern having 492
horizontal rows and 380 vertical rows. This provides, for example,
a photosensitive area of 6.6.times.8.8 mm.sup.2. Vertical transfer
channels 13 and overlfow drains 14 are placed between each vertical
rows of photosensors 12. A horizontal transfer channel 15 is placed
at the common end of the vertical transfer channels 13. An output
terminal 16 is provided at the end of the horizontal transfer
channel 15.
A partial cross sectional view of the CCD device taken along the
line 2--2 in FIG. 1 is schematically shown in FIG. 2 together with
a color filter array provided on the surface of the CCD device.
Photodiodes 12 are formed by a N.sup.+ -type diffused region at the
surface of the P-type substrate 11. Vertical transfer channels 13
are also N.sup.+ -type diffused areas extending along the vertical
rows of photosensors 12. Positioned over vertical transfer channels
13 are transfer electrodes 17 made of polysilicon buried in a
SiO.sub.2 layer 18 on the surface of substrate 11. Two vertical
transfer electrodes 17, partly overlapping each other, are provided
for each photosensor 12. Between photosensor region 12 and vertical
transfer channel regions 13, a charge gating electrode 19 is
provided which gates and transfers charges produced in photosensor
regions 12 to the vertical channel region. Gate electrodes 19 are
activated when transfer signals are applied, as explained later.
Aluminum light shield layers 20 are provided on the SiO.sub.2 layer
18. Except for the photosensor areas 12, light shield layers 20
covers the entire surface area. Light shield layers 20 are
electrically biased so that any excess charges generated in
photosensor area 12 will flow into overflow drains 14, instead of
flowing into vertical transfer channels 13. Overflow .[.chains.].
.Iadd.drains .Iaddend.14 are formed of N.sup.++ diffused regions.
Light shield layers 20 and SiO.sub.2 layers 18 are coated by PSG
glass layer 21. Positioned over PSG glass layer 21, a color filter
array 22 is laminated by a binding layer 23. Color filter array 22
has filter elements 24 arrayed on the lower surface of a glass
substrate 25. The P.sup.+ regions 26 shown in FIG. 2 are channel
stopping regions which isolate vertical transfer channels 13 from
overflow drains 14.
Four transfer drive signals .PHI..sub.1 -.PHI..sub.4 are supplied
to vertical transfer electrodes 13 through drive lines 27-30. Each
respective drive line is connected to a corresponding vertical
transfer electrode 17, as shown in FIG. 1. For example, as shown in
FIG. .[.7(A).]. .Iadd.7(a).Iaddend., .PHI..sub.1 is connected to
electrode 17-1, .PHI..sub.2 is connected to electrode 17-2,
.PHI..sub.3 is connected to electrode 17-3, and .PHI..sub.4 is
connected to electrode 17-4. Likewise, .PHI..sub.1 would also be
connected to electrode 17-5, et cetera. Each horizontal drive line
is connected in common with all the vertical transfer electrodes 17
arranged along the same horizontal lines (not shown in FIG. 1).
Drive lines 27 and 29 are also connected to charge gating
electrodes 19. For example, as shown in FIG. .[.7a.].
.Iadd.7(a).Iaddend., line 27 is connected to gate 19-1 while line
29 is connected to gate 19-2. Horizontal transfer electrodes 31 are
arrayed along the surface of horizontal transfer channel 15. These
electrodes are provided so that each electrode corresponds to a
respective vertical array of vertical transfer electrodes 17 and
photosensor array 12. Two phase drive signals .phi..sub.1, and
.phi..sub.2 are supplied, through drive lines 32 and 33, to
horizontal transfer electrodes 31. Drive lines 32 and 33 are
alternately connected to transfer channel 15.
FIG. 3 schematically shows a filter array 22 of FIG. 2. Each filter
element corresponds to a respective photosensor. Only a portion of
the filter array having 492.times.380 elements, each having an area
of 13.times.32 mm.sup.2, is shown in FIG. 3. This filter array
comprises the following three different color filter elements:
green (G), yellow (Ye) and cyan (Cy). The green elements pass only
green light. The yellow elements pass only red (R) and green (G)
light. The cyan elements pass only green (G) and blue light. In the
first horizontal row .[.1.sub.1 .]. .Iadd.l1 .Iaddend.(FIG. 3), the
Ye and G elements are alternately arranged. In the second row
.[.12.]. .Iadd.l2.Iaddend., the Cy and G elements are alternately
arranged in the same manner as the first row. The third row
.[.13.]. .Iadd.l3 .Iaddend.is identical to the first row. In the
fourth row .[.14.]. .Iadd.l4.Iaddend., G and Cy are alternately
arranged in the same manner as the first row. Therefore, the filter
array comprises a number of array units, each unit comprising
2.times.4 element array, as shown by dotted line U; this unit array
is repeated horizontally and vertically.
Operation of the solid-state image pickup device according to the
invention will now be explained. Incident image light, shown by
arrow 34 in FIG. 2, is divided into component colors while passing
through filter array 22. Each component color light is converted
into an electrical charge by photosensor 12 and temporarily stored
therein. The charge is read out, under the control of charge gating
electrodes 19, into vertical transfer channel 13.
In scanning the odd fields, a set of gating signals
.PHI.1(G)-.PHI.4(G) (FIG. 6(a)) are applied to vertical transfer
electrodes 13 through drive lines 27-30. The coupling signals are
superimposed on 4-phase drive signals .PHI.1-.PHI.4 at the end of
vertical blanking period of the television display system before
the vertical transfer period begins. The enlarged view of FIG. 7(a)
explains the mixing of the charge. The gating signals
.PHI.1(G)-.PHI.4(G) are applied to input terminals 35-1-35-4,
respectively. When gate signal .PHI.1(G) is applied to vertical
transfer electrode 17-1 through input terminal 35-1, gate electrode
19-1 is biased to form a deep potential well in the region under
electrode 19-1. During a first gating sequence, the charge stored
in photosensor 12-1 is then transferred to the vertical transfer
channel 13 by passing under vertical transfer electrode 17-1, as
shown by arrow 36. When gate signal .PHI.2(G) is applied, the
charge under electrode 17-1 transferred to the channel region under
electrode 17-2. During a second gating sequence, the gate signal
.PHI.3(G) is applied and gate electrode 19-2 is likewise biased to
form a deep potential well under electrode 19-2. The charge stored
in photosensor 12-2 is thus transferred via electrode 19-2 into the
channel region under electrode 17-3, as shown by dotted arrow 37.
Simultaneously, the charge under electrode 17-2 is transferred to
the region under electrode 17-3. In this channel region the charge
generated in sensors 12-1 and 12-2 are mixed together. By applying
gate signal .PHI.4(G), the mixed charge is transferred along
vertical channel 13 to the adjacent region under electrode
17-4.
Since gating signals .PHI.1(G)-.PHI.4(G) are provided just prior to
the beginning of every field scanning period, the photosensor
charges are read out and transferred to, and mixed in, the vertical
transfer channel. They are then transferred toward the horizontal
transfer channel during the field scanning period during which time
the vertical transfer signals .PHI.1-.PHI.4 are cyclically applied
to the vertical transfer electrodes 17. In this way, the charge
generated by each photosensor in an odd horizontal row is mixed
with the charge generated by a photosensor in an adjacent
horizontal row. Image signals for odd horizontal lines thus formed
are transferred, in horizontal transfer channel 15, toward output
terminal 16 in response to horizontal drive signal .phi..sub.1 and
.phi..sub.2. Output terminal 16 then supplies the color image
signals to a signal processor.
In scanning the even fields, photosensors in even rows are first
read out and the charge generated in each photosensor is mixed with
the charge generated by photosensors in next adjacent horizontal
rows, as shown by FIGS. 6(b) and 7(b). From these figures, it is
noticed that the order of 4-phase transfer signals .PHI.1, .PHI.2,
.PHI.3, .PHI.4 is changed to the order .PHI.3, .PHI.4, .PHI.1,
.PHI.2. This change in the order of the transfer signals can be
accomplished by switching a 4-phase clock pulse generator included
in pulse generator 45 (FIG. 8) with field index pulses, generated
at the beginning of every odd field. Thus, during a first gating
sequence the charge in photosensor 12-2 is transferred to vertical
transfer channel 13 by applying gating signal .PHI.1(G) to gate
electrode 19-2 as shown by arrow 27. By applying gating signal
.PHI.2(G) to transfer electrode 17-4, the charge under electrode
17-3 is transferred to the region under electrode 17-4. During a
second gating sequence, the gating signal .PHI.3(G) is applied to
transfer electrode 17-5. The charge in photosensor 12-3 is thus
transferred into vertical transfer channel, as shown by dotted
arrow 39, under the control of gate electrode 19-3 which is also
driven by gating signal .PHI.3(G). Simultaneously, the charge under
electrode 17-4 is transferred to the region under electrode 17-5
where this charge is mixed with the charge from photosensor 12-3.
Gating signal .PHI.4(G) transfers the mixed charge to the region
under electrode 17-6. Subsequently, drive signals .PHI.1-.PHI.4
continue to transfer the charges toward horizontal transfer channel
15. Thus, even lines of image signals are obtained at output
terminal 16. In this way interlace scanning is carried out.
Color signal processing will now be explained. FIG. 8 shows a
schematic diagram of a so-called single-plate type color television
camera system incorporating the CCD device mentioned above.
Incident image light passing through a lens 41 and a color filter
array 42 (e.g., the one shown in FIG. 3), projects an image on the
surface of a CCD image pickup device 43 (e.g., FIG. 1). CCD device
43 is driven by pulse signals fed to it from a drive circuit 44.
Drive circuit 44 generates various kinds of pulse signals which are
required for the CCD device 43 to generate its output image signal.
Drive circuit 44 is coupled to pulse generator 45 which generates
timing pulses for controlling the camera system shown in FIG. 8.
Color signal components obtained by each horizontal scanning of the
CCD device are shown in FIG. 4. The signal in the first odd
horizontal line L1 is a sum of the signals generated by light
components passed through the filter elements in the first and
second horizontal row .[.L.sub.1 .]. .Iadd.l1 .Iaddend.and
.[.L.sub.2 .]. .Iadd.l2 .Iaddend.of FIG. 3. If this relationship is
expressed as .[.L1=L.sub.1 +L.sub.2 .]. .Iadd.L1=l1+l2.Iaddend.,
then L2 and L3 are respectively expressed as .[.L2=L.sub.3
+L.sub.4, L3=L.sub.5 +L.sub.6 .]. .Iadd.L2=l3+l4,
L3=l5+l6.Iaddend.. Horizontal scanning lines L1, L2, L3 . . . are
those that occur during the odd field scanning period of interlaced
scanning.
On the other hand, during even field scanning, the signal in the
first horizontal line L1' represents the sum of the signals
generated by light components passed through the color filter
elements in the second and third row .[.L.sub.2, L.sub.3 .].
.Iadd.l2, l3 .Iaddend.of FIG. 3. Thus, the relationship between L1'
and .[.L.sub.2, L.sub.3 .]. .Iadd.l2, l3 .Iaddend.is again
expressed as: .[.L1'=L.sub.2 +L.sub.3 .]. .Iadd.L1'=l2+l3.Iaddend..
Similarly, L2', L3' are respectively expressed as: .[.L2'=L.sub.4
+L.sub.5, L3'=L.sub.6 =L.sub.7 .]. .Iadd.L2'=l4+l5,
L3'=l6+l7.Iaddend.. In the first horizontal line L1, color signal
Ye+Cy and 2G alternately appear. Signal Ye+Cy can be expressed as
R+2G+B, since signal Ye and Cy are respectively expressed as R+G
and G+B. Accordingly, in horizontal line L1, R+2G+B and 2G signals
are alternately repeated as shown in FIG. 5(a). Similarly, signals
R+2G and B+2G are alternately repeated along horizontal line L2 as
shown in FIG. 5(b). The cycle of these signals is selected as 3.58
MHz which is the color subcarrier signal frequency for NTSC color
television signals. It should be noted that the color filter array,
according to the invention, is so designed that the color signals
obtained during every horizontal scanning of odd fields are the
same as those obtained during even field scanning.
Returning to FIG. 8, the output signal from CCD device 43 is
supplied to a wide band amplifier 46. Amplifier 46 may be an
amplifier having a sample and hold function controlled by output
pulses from pulse generator 45. The output signal from amplifier 46
passes through a first low pass filter (LPF) 47 which passes
frequencies below 3 MHz to provide a luminance signal Y at its
output. Luminance signal Y is then fed to a color encoder 48. The
output signal of amplifier 46 is supplied to a second LPF 49 which
passes frequencies below 0.5 MHz to provide a low frequency color
signal at its output. This low frequency color signal is fed to a
color matrix circuit 50. The output signal of amplifier 46 further
passes through a band pass filter (BPF) 51 which passes frequencies
from 3 MHz to 4 MHz, centered approximately at 3.58 MHz. A color
subcarrier signal having 3.85 MHz frequency modulated by R and B
color component lights is extracted at the output of BPF 51.
The output signal of BPF 51 is fed to an adder circuit 52, a 1 H
delay circuit 53 and a .[.substractor.]. .Iadd.subtractor
.Iaddend.circuit 54. Delay circuit 53 provides a delay time of one
horizontal scanning period. The output signal from 1H delay circuit
53 is supplied to adder circuit 52 and to subtractor circuit
.[.84.]. .Iadd.54.Iaddend.. When the subcarrier modulated by color
signals R and B in the second horizontal line L2 (shown in FIG.
5(b)) is supplied to the input of addition circuit 52, the
subcarrier modulated by R and B signals in the first line L1 (shown
in FIG. 5(a)) is supplied to another input of addition circuit 52
via 1H delay circuit 53. With regard to the color modulated
components in two adjacent horizontal lines, the R components are
in phase and B components are out of phase by 180.degree. (See
FIGS. 5(a) and (b)). Consequently, a subcarrier modulated by only R
components is obtained at the output of addition circuit 52.
Similarly, a subcarrier modulated by only B components is obtained
at the output of subtraction circuit 54. These color modulated
subcarrier signals are then demodulated by a first and second
demodulation circuit 55 and 56 to obtain R and B low frequency
signals, respectively, as shown in FIGS. 5(c) and (d). On the other
hand, the signal which has passed through the second LPF 49 is
converted to an unmodulated low frequency signal with an amplitude
of R/2+2G+B/2 and is supplied to color matrix circuit 50 together
with the R and B low frequency signals obtained from first and
second demodulation circuits 55 and 56. Matrix circuit 50 generates
a low frequency G signal by processing these three input color
signals. Luminance signal Y from first LPF 47 and the three color
signals R, G and B thus obtained are supplied to a color encoder
57, which generates NTSC color television signals.
It should be noted that there are various modifications within the
scope of the invention. Especially, color filter array can be
modified as shown in FIGS. 9-14. Shown in these figures, for
simplicity, are the filter pattern of only .[.6.times.6.].
.Iadd.6.times.5 .Iaddend.elements. The use of the color filter
arrays according to the invention simplifies the process for
manufacturing the filter arrays since overlapped portions of Ye and
Cy form G filter elements. Practically, only two different kinds of
processes (i.e., forming Ye and Cy elements) need be used to
produce the required four different color elements: Ye, G, Cy and
W. Thus, the manufacturing steps are reduced to half or one third
of those required for conventional processes.
Though the charge gating electrodes 19 shown in FIGS. 1, 2 and 7
are separately provided between vertical transfer electrodes 13 and
photodiodes 12, they can also be formed by extending vertical
transfer electrodes 13 towards photodiodes 12, as shown in FIGS. 15
and 16.
Although an interline transfer type CCD device is disclosed in the
embodiments mentioned above, the invention can also be applied to a
frame transfer type CCD device. FIGS. 17-19 .[.shows.]. .Iadd.show
.Iaddend.such an embodiment of the invention. FIG. 17 schematically
shows a sensor area of a frame transfer type CCD device and a
filter array. The filter array 71 is formed by repeating the
2.times.4 filter element unit as shown in the right-hand portion of
the filter array in FIG. 17.
Two vertical transfer electrodes 72 are provided for each filter
element 73. Transfer electrodes 72 are preferably made transparent
for passing the image light. Incident image light passing through
filter element 73 and vertical transfer electrodes 72 into the
semiconductor substrate 75 generates charge 74 corresponding to the
intensity of the incident light, as shown in FIG. 18. During the
storage period, the charges generated in the areas corresponding to
two filter elements which are arrayed in adjacent pair of
horizontal rows are mixed together. This is done by applying mixing
signals .PHI..sub.1 -.PHI..sub.4, to the vertical electrodes, as
shown in FIG. 19. These signals have a waveform consisting of two
different voltage levels VH and VL (e.g., VH equals 10 V, VL equals
1 V). Each of these signals, however, has a fixed level during the
storage period. During the odd scanning field, the mixing signals
shown in FIG. 19(a) are applied to transfer electrodes 72. That is,
VH is applied to electrodes 72-2, 72-3 and V.sub.2 is applied to
electrodes 72-1, 72-4 (see FIGS. 17 and 19(a)). This causes a
potential well to be formed under electrodes 72-2 and 72-3 and the
charges generated in the areas under electrode 72-1, 72-2 gather
into these wells, as shown in FIG. 18(a) which is a sectional view
taken along line 18--18 of FIG. 17. It is understood from FIGS. 17
and 18(a) that the charges generated by the photosensors, arranged
in every two pairs 80 of adjacent electrodes (e.g., 72-1, 72-2,
72-3 and 72-4), are mixed together, during the odd field scanning.
After the storage period is over, the 4-phase transfer signals
.PHI..sub.1 -.PHI..sub.4 are applied to drive transfer electrodes
72 for transferring the mixed charges along the vertical direction
towards the storage area (not shown).
During the even scanning field, the mixing signals shown in FIG.
19(b) are applied to transfer electrodes 72. During the storage
period, VH (i.e., 10 V) is applied to electrodes 72-4, 72-5 and VL
(i.e., 1 V) is applied to electrodes 72-3, 72-6, as shown in FIG.
17. This causes a potential well to be formed under electrodes
72-4, 72-5; in this well the charges are mixed, as shown in FIG.
18(b). It is clear that the charges generated by the photosensors,
arranged in every two pairs 81 of adjacent electrodes (e.g., 72-3,
72-4, and 72-5, 72-6), are mixed together during the even
.[.canning.]. .Iadd.scanning .Iaddend.fields. After the storage
period is over, the 4-phase transfer signals .PHI..sub.1
-.PHI..sub.4 are used to drive transfer electrodes 72 for
transferring the mixed charge along the vertical direction towards
the storage area. In this embodiment, it is clear from FIG. 19 that
the 4-phase transfer signals which are used in the odd and even
fields have the same waveform except for their order.
* * * * *