Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1999-05-24
2004-12-14
Christensen, Andrew (Department: 2615)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S241000, C348S302000, C348S308000, C348S312000, C348S317000
Reexamination Certificate
active
06831685
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solid-state image pickup element for outputting a signal of incident video light and an image pickup apparatus using the same.
2. Related Background Art
A solid-state image pickup element according to a first example of prior art will be described.
FIG. 1
is a circuit diagram of the solid-state image pickup element of the first example of prior art. Referring to
FIG. 1
, the solid-state image pickup element comprises a photodiode
101
as a photodetecting element for generating charges corresponding to incident light, a floating diffusion region
102
, a transfer transistor
103
for transferring charges generated by the photodiode
101
to the floating diffusion region
102
, a reset transistor
104
for removing charges stored in the floating diffusion region
102
, amplification transistors
105
,
106
, and
107
, a capacitor
108
for storing a voltage generated in the floating diffusion region upon resetting, a capacitor
109
for storing a voltage generated in the floating diffusion region in an operative state, a switching transistor
110
for connecting an amplifier to the capacitor
108
, a switching transistor
111
for connecting an amplifier to the capacitor
109
, a capacitor discharging transistor
112
for discharging the capacitors
108
and
109
, buffers
113
and
114
, switching transistors
115
and
116
for switching the capacitors
108
and
109
to capacitors of another line and supplying the voltages of the capacitors
108
and
109
to the buffers
113
and
114
, respectively, reset transistors
117
and
118
for resetting input voltages to the buffers
113
and
114
, respectively, horizontal output lines
119
and
120
, a vertical scanning circuit
121
, and a horizontal scanning circuit
122
. The amplifier formed from the transistors
105
,
106
, and
107
serves as a source-follower-type amplifier only when the transistors
106
and
107
are ON. The photodiode
101
, floating diffusion region
102
, and transistors
103
,
104
,
105
, and
106
form one pixel.
FIG. 2
is a timing chart showing the operation timing of the solid-state image pickup element shown in FIG.
1
. The operation of the solid-state image pickup element shown in
FIG. 1
will be described with reference to
FIGS. 1 and 2
.
At time T801, a vertical scanning start pulse is input to a terminal
2
,: a vertical scanning pulse is input to a terminal
3
to select the first line, and a signal
20
a
goes high (not shown). A pulse of high level is input to a terminal
8
to reset the floating diffusion region
102
. Terminals
11
,
12
, and
13
are simultaneously set at high level, and the capacitors
108
and
109
are reset. At time T802, the reset pulse at the terminal
8
goes low to set the floating diffusion region
102
in an electrically floating state. At time T803, a pulse of high level is applied to a terminal
10
, and simultaneously, a pulse of high level is applied to the terminal
12
, so the voltage (reset voltage) immediately after resetting the floating diffusion region
102
is read out to the capacitor
108
. At time T804, a pulse of high level is applied to a terminal
9
to transfer charges generated by the photodiode
101
to the floating diffusion region
102
. At time T805, pulses of high level are applied to the terminals
10
and
13
to read out the voltage (signal voltage+reset voltage) of the floating diffusion region
102
to the capacitor
109
. At time T806, the voltage at a terminal
14
changes from high level to low level to reset the horizontal output lines
119
and
120
. At the same time, a horizontal scanning start pulse is input to a terminal
5
, and a horizontal scanning pulse is input to a terminal
6
to start the signal read from line memories formed from capacitors of the respective columns. The input signal to the terminal
14
is in an opposite phase to that of the horizontal scanning pulse to prevent interference between the capacitors of the respective columns. Reset voltages of the respective columns are sequentially output from a terminal
16
. Sums of signal voltages and reset voltages of the respective columns are sequentially output from a terminal
17
. When the difference between two outputs is calculated by a subtracting means connected to the output side, a signal voltage containing no reset voltage that varies between pixels can be obtained. Hence, an output with a high S/N ratio, which contains no noise component due to a variation in reset voltage, can be obtained.
The photodiode
101
is reset at time T804 when charges are transferred from the photodiode
101
to the floating diffusion region
102
. Resetting is completed when the signal at the terminal
9
goes low to end transfer. After this, storage of charges corresponding to incident light is restarted. This storage operation continues until T804 of the next frame cycle.
From time T801B, the signals input to the terminals
3
,
8
,
9
,
10
,
11
,
12
,
13
,
5
,
6
, and
14
repeat their patterns from time T801 to time T801B. Referring to
FIG. 3
, by operation of the vertical scanning circuit
121
, the signal
20
a
goes high during only the first line period. Sequentially, a signal
20
b
goes high during only the second line period, and then, a signal
20
c
goes high during only the third line period. Because of the presence of a gate group
123
, signals supplied to the terminals
8
,
9
, and
10
become valid for only the first line during the first line period, for only the second line during the second line period, and for only the third line during the third line period, and this also applies to the following lines.
Hence, signals output from the terminals
16
and
17
are signals stored in the photodiodes at timings that sequentially shift in units of lines. This scheme is called a rolling shutter scheme.
The floating diffusion region
102
holds the transferred charges after charge transfer from the photodiode
101
until resetting and therefore functions as a memory.
A second example of prior art will be described next.
FIG. 4
is a circuit diagram of a solid-state image pickup element of the second example of prior art. The same reference numerals as in the first example of prior art shown in
FIG. 1
denote the same parts in
FIG. 4
, and a detailed description thereof will be omitted. A gate group
123
has the same arrangement as in the first example of prior art although it is represented by different symbols. In the second example of prior art, an OR gate
124
is inserted between the output terminal of the elements of the gate group
123
for receiving a signal from a terminal
9
and the gate of a transfer transistor
103
.
FIG. 5
is a timing chart showing the operation timings of the solid-state image pickup element shown in FIG.
4
. The operation of the solid-state image pickup element shown in
FIG. 4
will be described with reference to
FIGS. 4 and 5
.
At time T901, pulses of high level are applied to terminals
8
and
19
to reset floating diffusion regions
102
of all pixels and reset photodiodes
101
of all pixels. When resetting is ended, storage of charges corresponding to incident light by the photodiodes
101
of all pixels is started. At time T902, a pulse of high level is applied to the terminal
19
again to transfer charges stored in the photodiodes
101
of all pixels to the floating diffusion regions
102
. After this pulse of high level goes low, the charges transferred to the floating diffusion regions
102
are held. At time T903, a vertical scanning start pulse is input to a terminal
2
, and a vertical scanning pulse is input to a terminal
3
to select the first line, and a signal
20
a
goes high (not shown). At time T903, pulses of high level are applied to terminals
11
,
12
, and
13
to reset capacitors
108
and
109
. At time T904, pulses of high level are applied to terminals
10
and
12
to read out (signal voltage+reset voltage) from the photodiode of the floating diffusion region
102
Hiyama Hiroki
Kochi Tetsunobu
Koizumi Toru
Ogawa Katsuhisa
Sakurai Katsuhito
Christensen Andrew
Genco Brian
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