Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
1998-11-10
2001-07-10
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C358S406000, C358S482000, C358S483000, C250S208100
Reexamination Certificate
active
06259087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a calibration apparatus used for a multi-element sensor. More specifically, the present invention is directed to such a calibration apparatus capable of calibrating a high-resolution multi-element sensor used to sense an optical image of a facsimile, or an earth-monitoring multi-element sensor installed on a satellite.
2. Description of the Related Art
Conventionally, a multi-element sensor installed in a facsimile, or a satellite may sense an image signal, and further is electrically calibrated so as to periodically confirm operation conditions of electronic circuitry employed in an entire system.
One typical multi-element sensor introduces the following electric calibration method. That is, while using two levels of signals, namely, a zero level signal and an electric calibration signal as a reference, the sensor signal is electrically calibrated.
FIG. 7
is a timing chart for the various signals related to the typical multi-element sensor with respect to the time sequential operation.
As shown in FIG.
7
(
a
), an image signal is outputted from the multi-element sensor during a time period of “t1”, either a zero level signal or an offset signal is outputted during a time period of “t2”, and an electric calibration signal is outputted during a time period of “t3”. The time period of “t2” succeeds the first-mentioned time period of “t1”, and the time period of “t3” succeeds this time period of “t2”.
Conventionally, the image signal outputted during the time period of “t1” is calibrated based upon both the zero level signal outputted during the time period of “t2” and the electric calibration signal outputted during the time period of “t3”.
FIG.
7
(
b
) is a timing chart for indicating an image signal which has been calibrated by employing the zero level signal and the electric calibration signal with respect to the time sequential operation.
This conventional calibration method is described in, for example, Japanese Patent Laid-open Publication Nos. Hei5-183143 and Hei9-37022.
On the other hand, in a multi-element sensor, a minus-offset may be set to a zero level signal in order to widen a dynamic range of this multi-element sensor. Also, a zero level of this multi-element sensor may be set and this set level exceeds a preselected sensitivity, since this sensor may detect a light amount higher than a preselected light level.
In this conventional sensor calibration technique, since the image signal is calibrated based upon the two levels of the zero level signal and the electric calibration signal, both the offset and the gain of this sensor can be hardly corrected.
Also, the conventional multi-element sensor calibration apparatus presents the following problem. That is, within the image signals outputted from the multi-element sensor whose elements are arranged in a linear manner, the image signal outputted from the even-numbered multi-element sensor and also the image signal outputted from the odd-numbered multi-element sensor pass through the different registers and the different amplifiers. Since the offset amounts of the respective registers and also the gains of the respective amplifiers are different from each other, there is a slight difference between the electrical characteristics of the image signal derived from the even-numbered multi-element sensor, and the electrical characteristics of the image signal derived from the odd-numbered multi-element sensor.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-described problems, and therefore, has an object to provide a multi-element sensor calibration apparatus capable of continuously calibrating the multi-element sensor irrespective of solid-state characteristic differences produced in registers and also amplifiers, through which image signals of this multi-element sensor pass.
To achieve the above-described object, a calibration apparatus used for a multi-element sensor, according to an aspect of the present invention, is featured by comprising:
a light reception unit for receiving incident light to convert the received incident light into an electric signal;
calibration signal output means for outputting a calibration signal used to calibrate the electric signal;
transfer means for transferring the electric signal and the calibration signal;
gate means for executing a gating operation of the electric signal in such a manner that when the gate means is set to an ON state, the electric signal derived from the light reception unit is outputted to the transfer means whereas when the gate means is set to an OFF state, outputting of the electric signal to the transfer means is interrupted; and
calibration signal output control means for performing an output control of the calibration signal in such a way that when the gate means is set to an ON state, the calibration signal is not outputted to the transfer means, whereas when the gate means is set to an OFF state, the calibration signal is outputted to the transfer means.
Also, according to another aspect of the present invention, adjustment means for adjusting a level of the calibration signal is provided between the transfer means and the calibration signal output control means.
Also, according to another aspect of the present invention, amplification means for amplifying the electric signal and the calibration signal, which are transferred by the transfer means, is provided at a post stage of the transfer means.
Also, according to another aspect of the present invention, the light reception unit includes a plurality of optical sensors;
the multi-element sensor calibration apparatus includes at least two sets of each of the calibration signal output means, the transfer means, the gate means, and the calibration signal output control means; and
the two sets of gate means are arranged in correspondence with a respective portion of the plurality of optical sensors.
Further, according to another aspect of the present invention, the multi-element sensor calibration apparatus is featured by further comprising:
at least two sets of adjustment means for adjusting a level of the calibration signal and positioned between the respective calibration signal output control means and the respective transfer means.
Further, according to another aspect of the present invention, the multi-element sensor calibration apparatus is featured by further comprising:
at least two sets of amplification means for amplifying the electric signals and the calibration signals, which are transferred by the at least two sets of transfer means, positioned at post stages of the respective transfer means, respectively.
Also, according to another aspect of the present invention, the calibration signal derived from the calibration signal output means has at least two uniform levels.
Also, according to another aspect of the present invention, the gate means and the calibration signal output control means are controlled to substantially simultaneously output the electric signal and the calibration signal.
Also, according to another aspect of the present invention, the electric signal contains at least an image signal and a zero level signal.
Also, according to another aspect of the present invention, the electric signal contains at least an image signal and an offset signal.
REFERENCES:
patent: 5317423 (1994-05-01), Harada
patent: 5963338 (1999-10-01), Harada
patent: 5-183143 (1993-07-01), None
patent: 9-37022 (1997-02-01), None
Le Que T.
Luu Thanh X.
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
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