Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1999-07-23
2004-08-24
Christensen, Andrew (Department: 2615)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S607000, C358S463000
Reexamination Certificate
active
06781624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a signal processing apparatus having a noise removing circuit, a signal processing apparatus for outputting individual signals of a plurality of signal sources and at least the maximum and minimum signals from a plurality of signal sources, and an image pickup apparatus using the signal processing apparatus.
2. Related Background Art
FIG. 1
is a signal processing apparatus for sequentially outputting signals.
Referring to
FIG. 1
, signals S
1
, S
2
, . . . , Sn are sequentially output to an output line
102
through a non-inverting output circuit (voltage follower circuit)
103
by controlling a MOS transistor
101
by a shift register
100
.
FIG. 2
shows a photoelectric conversion apparatus having a noise removing circuit.
An amplified photoelectric conversion apparatus is disadvantageous because of large noise generated in pixels and therefore requires a noise removing circuit. Examples of amplified photoelectric conversion apparatus are a BASIS and CMOS sensor. Although
FIG. 2
shows a CMOS sensor having a two-dimensional array of photoelectric conversion elements
70
, even if the sensor is a linear sensor or a BASIS sensor, a same noise removing circuit is used in those sensors.
Referring to
FIG. 2
, the photoelectric conversion apparatus includes horizontal driving lines
71
for controlling lines, vertical output lines
72
for outputting pixel outputs to a noise removing circuit
74
, amplified MOS transistors
73
of the pixels
70
, load MOS transistors, and a constant current source. The noise removing circuit
74
is generally called an S-N noise removing circuit and comprises capacitances C
TN
77
for storing N charges, capacitances C
TS
78
for storing S charges, switch MOS transistors
75
and
76
for the capacitances, and horizontal driving MOS transistors
79
and
80
driven by a horizontal scanning circuit
85
. An S signal and N signal are input to a differential amplifier
84
through voltage follower circuits
82
and
83
, respectively, to remove noise and are output from the noise removing circuit. Let V
P
be the optical output from the pixel
70
, V
N
be noise, C
T
be the storage capacitance value, and C
H
be the parasitic capacitance of the horizontal output line. Then, a final output V
OUT
is given by
V
out
=
C
T
C
T
+
C
H
{
(
V
P
+
V
N
)
-
V
N
}
=
C
T
C
T
+
C
H
V
P
However, the prior arts have the following problems.
In the prior art shown in
FIG. 1
, since a signal is output through the non-inverting output circuit, the noise signal (e.g., offset signal) from the non-inverting output circuit is added and output together with the signal.
The prior art shown in
FIG. 2
has the following problems:
(1) Since two large MOS capacitances are formed, the chip area increases. Especially, as the device shrinks in feature size, most area is occupied by the MOS capacitances, resulting in a serious problem.
(2) When the S capacitance value shifts from the N capacitance value, the noise correction effect degrades (variation in C
T
)
(3) The sensitivity decreases to C
T
/(C
T
+C
H
) because of the capacitance division ratio of the storage capacitance to the parasitic capacitance.
SUMMARY OF THE INVENTION
It is the first object of the present invention to read out an accurate signal free from noise.
It is the second object of the present invention to reduce the chip area.
In order to achieve the above object, according to an aspect of the present invention, there is provided a signal processing apparatus comprising a signal source, a non-inverting output circuit for outputting a signal from the signal source, and noise signal removal means for, when the signal from the signal source is output from the non-inverting output circuit, removing a noise signal in the non-inverting output circuit and causing the non-inverting output circuit to output the signal from the signal source.
According to another aspect, there is provided a signal processing apparatus comprising a signal source, arithmetic means for performing an arithmetic operation, and a non-inverting output circuit for outputting a signal from the arithmetic means, wherein the arithmetic means including at least transfer means for transferring a signal from the signal source to the non-inverting output circuit, and difference signal formation means for forming a difference signal obtained by subtracting a signal from the non-inverting output circuit from the signal from the signal source.
According to still another aspect, there is provided a signal processing apparatus comprising a plurality of signal sources, a non-inverting output circuit for outputting signals from the plurality of signal sources, specific value signal output means for causing the non-inverting output circuit to output a maximum or minimum signal of at least two of the plurality of signal sources, and noise signal removal means for, when the signal from the signal source is output from the non-inverting output circuit, removing noise signal in the non-inverting output circuit and causing the non-inverting output circuit to output the signal from the signal sources.
According to still another aspect, there is provided a signal processing apparatus comprising a plurality of signal sources, specific value detection means for outputting a maximum or minimum signal of the plurality of signal sources, the specific value detection means having a function of sequentially outputting individual signals from the plurality of signal sources, and driving means for switching the function of the specific value detection means.
According to still another aspect, there is provided a signal processing apparatus comprising a plurality of signal sources, maximum detection means for outputting a maximum signal of the plurality of signal sources, minimum detection means for outputting a minimum signal of the plurality of signal sources, the maximum or minimum detection means having a function of sequentially outputting individual signals from the plurality of signal sources, and driving means for switching the function of the maximum or minimum detection means having the function of sequentially outputting the individual signals.
REFERENCES:
patent: 5065443 (1991-11-01), Farchmin
patent: 5942920 (1999-08-01), Ueno
patent: 2072450 (1981-09-01), None
Canon Kabushiki Kaisha
Christensen Andrew
Fitzpatrick ,Cella, Harper & Scinto
Wu Dorothy
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