Coded data generation or conversion – Analog to or from digital conversion – Analog to digital conversion
Reexamination Certificate
2001-09-07
2003-03-25
JeanPierre, Peguy (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Analog to digital conversion
Reexamination Certificate
active
06538591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a signal transfer apparatus, imaging apparatus and radiation image pick-up system using it. More particularly, it is suitable to photoelectric conversion apparatus applicable as image input units of X-ray detectors for medical or non-destructive internal inspection as well as business machines such as copying machines and facsimile machines.
2. Related Background Art
Currently, the mainstream of radiation image pick-up apparatus used for medical diagnosis is a so-called film-based type which involves exposing a human body to radiation, converting the rays that passed through the human body into visible light by means of a phosphor, and exposing a film to it.
However, there is a growing demand for “digitization of X-ray image information” because of improved diagnostic efficiency achieved by immediacy in acquisition of image information, which is not possible with the conventional film-based type that requires a developing process, as well as because of ease of image transmission necessary for recording, management, and remote medical diagnosis. Recently, X-ray image pickup apparatus have been proposed which employ CCD solid-state image sensing devices or amorphous silicon devices instead of films.
FIG. 29
shows an example of two-dimensional photoelectric conversion apparatus applicable to X-ray image pickup apparatus, described in Japanese Patent Application Laid-Open No. 9-307698.
In
FIG. 29
, reference numeral
101
denotes a photoelectric conversion circuit unit;
110
denotes a light-receiving area which converts incident light into signal charges;
111
denotes interelectrode capacitance for storing the signal charges resulting from photoelectric conversion carried out by the light-receiving area
110
; S
1-1
to S
3-3
denote photoelectric conversion elements, each comprising a light-receiving area
110
and interelectrode capacitance
111
; M
1
, M
2
, and M
3
denote matrix signal wirings; T
1-1
to T
3-3
denote switching elements for transferring the signal charges formed by the photoelectric conversion elements S
1-1
to S
3-3
to the matrix signal wirings M
1
, M
2
, and M
3
; G
1
, G
2
, and G
3
denote gate drive wirings for driving the switching elements T
1-1
to T
3-3
; and C
1
, C
2
, and C
3
denote load capacitances of the matrix signal wirings M
1
, M
2
, and M
3
, respectively. Reference numeral
102
denotes a shift register serving as a gate line drive circuit unit for applying drive signals to the gate drive wirings G
1
, G
2
, and G
3
. Reference numeral
107
denotes a bias supply for the photoelectric conversion elements.
Reference numeral
103
denotes a read circuit unit for converting parallel signals transferred from the matrix signal wirings M
1
to M
3
into series signals and outputting the resulting series signals; S
RES1
, S
RES2
, and S
RES3
denote reset switches of the load capacitances C
1
, C
2
, and C
3
, respectively; CRES denotes a control signal applied to S
RES1
, S
RES2
, and S
RES3
; A
1
to A
3
denote buffer amplifiers whose non-inverting input terminals are connected with the matrix signal wirings M
1
to M
3
and which convert the impedance of output signals received from the matrix signal wirings; Sn
1
to Sn
3
denote sampling switches for sampling the output signals outputted via the buffer amplifiers A
1
to A
3
; SMPL denotes a voltage pulse applied to the sampling switches Sn
1
to Sn
3
; C
L1
to C
L3
denote sampling capacitors; B
1
to B
3
denote buffer amplifiers whose non-inverting input terminals receive sampled output signals and which convert the impedance of the output signals; Sr
1
to Sr
3
denote read switches for reading the outputs of the buffer amplifiers B
1
to B
3
in sequence as series signals;
104
denotes a shift register serving as a switch drive circuit unit for reading; and
105
denotes an output buffer amplifier.
Reference numeral
106
denotes an A/D conversion circuit unit for converting analog signals into digital signals.
Incidentally, although a 9-pixel (3×3), two-dimensional photoelectric conversion apparatus is shown in
FIG. 29
for the sake of simplicity, actual photoelectric conversion apparatus consist of more pixels depending on their applications.
FIG. 30
is a timing chart illustrating the operation of the photoelectric conversion apparatus shown in FIG.
29
.
The signal charges resulting from photoelectric conversion by the photoelectric conversion elements S
1-1
to S
3-3
are stored in the interelectrode capacitances
111
in the photoelectric conversion elements for a certain period of time. Then, when a first voltage pulse for transfer is applied to the gate drive wiring G
1
by the shift register
102
for a time t
1
, the switching elements T
1-1
to T
1-3
are turned on and the signal charges stored in the photoelectric conversion elements S
1-1
to S
1-3
in the first row are transferred, respectively, to the load capacitances C
1
, C
2
, and C
3
of the matrix signal wirings M
1
, M
2
, and M
3
. The potentials V
1
, V
2
, and V
3
of the load capacitances C
1
, C
2
, and C
3
after the signal charges are transferred vary with the amount of signal charge.
FIG. 30
shows a case in which the signal charges differ in amount from one another. The operation described so far is referred to as a transfer operation.
The signal charges in the matrix signal wirings M
1
to M
3
have their impedance converted, respectively, by the buffer amplifiers A
1
to A
3
in the read circuit unit
103
. Then, the sampling switches Sn
1
to Sn
3
are turned on by the SMPL pulse shown in
FIG. 30
for a time t
2
and the signal charges are transferred to the sampling capacitors C
L1
to C
L3
. This operation is referred to as a sampling operation.
Next, the read switches Sr
1
to Sr
3
are turned on in sequence each for a time t
3
by read pulses Sp
1
to Sp
3
from the shift register
104
. Consequently, the parallel signal charges transferred to the sampling capacitors C
L1
to C
L3
have their impedance converted by buffer amplifiers B
1
to B
3
, respectively, are read out as series signals from the final output amplifier
105
, and digitized by the A/D conversion circuit unit
106
. This operation is referred to as a read operation.
Then, the load capacitances C
1
to C
3
are reset by the application of the control signal CRES to the reset switches S
RES1
to S
RES3
for a time t
4
to prepare for a read operation of the next row. This operation is referred to as a reset operation.
Similarly, the gate drive wirings G
2
and G
3
are driven in sequence by the shift register
102
to read out all the pixel data of the photoelectric conversion elements S
2-1
to S
3-3
.
The load capacitances C
1
to C
3
of the matrix signal wirings M
1
to M
3
shown in
FIG. 29
actually consist of interelectrode capacitances (Cgs) formed at the intersections of gate electrodes of the switching elements T
1-1
to T
3-3
and electrodes on the signal lines M
1
to M
3
. For example, the load capacitance C
1
is given as the sum of the interelectrode capacitances (Cgs) of the three switching elements T
1-1
, T
2-1
, and T
3-1
connected to the signal line M
1
. The same applies to the load capacitances C
2
and C
3
. Thus, if the pixel array of the two-dimensional photoelectric conversion circuit unit consists of m rows and n columns, the load capacitance Ci (i=1 to n) of the matrix signal wiring Mi (i=1 to n) is given by the following general formula:
Ci=Cgs×m
(1)
The signal charges stored in the interelectrode capacitances
111
in the photoelectric conversion elements are transferred to the load capacitances Ci (i=1 to n) of the matrix signal wirings Mi (i=1 to n) through the transfer operation described above. If the interelectrode capacitance in the photoelectric conversion element is Cs and the signal charge is Qi, the potential Vi of the load capacitance Ci is given by:
Vi=Qi
/(
Cs+Ci
)=
Qi
/(
Cs+mCgs
) (2)
Since the
Kaifu Noriyuki
Kikuchi Shin
Morishita Masakazu
Sato Toshiaki
Shirai Eiji
Canon Kabushiki Kaisha
Jean-Pierre Peguy
LandOfFree
Signal transfer apparatus, and imaging apparatus and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Signal transfer apparatus, and imaging apparatus and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Signal transfer apparatus, and imaging apparatus and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3001254