Trixell S.a.s.

Thomson Tubes Electroniques

Trixell

Thales

Thierry Ducourant

Christophe Chaussat

Bruno Bosset

Marc Arques

Christophe Barnichon

Robert Neyret

Bruno Commere

Clément Atoyan

Paul Apard

Aysegul Van Oost

Clement Atoyan

A digital detector includes a conversion block intended to convert incident radiation into electric charge; an electronic card that converts the electric charge into a digital image, the conversion block comprising N conversion stages superposed on one another, N being an integer between 2 and M, each of the N conversion stages comprising: a monolithic substrate; a first converter assembly in the form of a polygonal matrix array, M being the number of sides of the polygonal matrix array, M preferably being equal to 4, and configured so as to generate the electric charge on the basis of the incident radiation; an addressing and driving module for addressing and driving the matrix array, the addressing and driving module being arranged on the monolithic substrate along one side of the polygonal matrix array; each of the N conversion stages being oriented by at least 1/M of a turn with respect to the other N−1 conversion stages of the conversion block, and with an orientation distinct from the other N−1 conversion stages of the conversion block.

Digital detector with superposed conversion stages

The present invention relates to a photosensitive device comprising a matrix of photosensitive pixels, in particular of the type produced by techniques for depositing semiconductor materials. The invention relates more particularly (but not exclusively) to the driving of such devices used for detecting radiological images. It also relates to a method of driving the photosensitive device. The photosensitive device includes means for adjusting the amplitude of the bias, allowing separate adjustment of the amplitude of the bias of the photosensitive pixels (Pto PPto P). The method of driving the photosensitive device consists, in the calibration phase, in adjusting the amplitude of the bias of each of the photodetector elements (Dp) separately from one another, so as to bring the output saturation levels of the two photosensitive pixels into maximum coincidence.

Photosensitive device and method for controlling same

A process for controlling a photosensitive device including at least one photosensitive point with a photodiode connected to a switching element. The process submits the photosensitive point to successive imaging cycles. Between a first imaging cycle and a second imaging cycle, the process produces a holding phase terminating at the start of the second imaging cycle. During this holding phase, whose duration is equal to several equal time intervals that are as short as possible, the photosensitive point is exposed to an optical flash at the start of each time interval. Between successive optical flashes, the photodiode is reverse biased. The junction region between the photodiode and the switching element has substantially the same potential at the end of each time interval.

Process for controlling a photosensitive device including a photosensitive point produced by techniques for depositing semiconductor materials

A process for correcting noise level of an image detector including photosensitive points arranged in rows and in columns. Within each row, the points are distributed into detector points and into corrector points. The detector points deliver a measurement value dependent on a luminous cue to which they are exposed. The corrector points deliver a dark value serving in the correction of the measurement values. Within at least one row, the detector points are distributed into at least two groups and the measurement values are corrected with a first or a second correction value depending on the group from which they originate. Such a process may find application to digitized-image detectors.

Method for correcting noise level in a digitized image detector

A method for temperature compensation of sensitivity of an image including photosensitive spots each with a photodiode connected to read circuits. The photosensitive spots are divided into detecting photosensitive spots, detecting an image when exposed to information carrying the image and sensitive to this information, and into blind spots protected from the information. When the photosensitive spots are taken to a reference temperature, an average leakage current in the photodiodes of the blind photosensitive spots is calculated and a first average is generated from signals from the blind photosensitive spots during a read operation. When the photosensitive spots are taken to an ambient temperature to be determined, another average is generated from signals from the blind photosensitive spots during another read operation. The ambient temperature is calculated from the average leakage current and from the distance between the two averages. A gain image or a quasi gain image matched to the ambient temperature is generated. An image recorded at the ambient temperature with the gain image or the quasi gain image is then corrected. Such a method may find application to radiological image detectors in particular.

Method for temperature compensation of an image sensor sensitivity

A method and device for temperature compensation of an image detector including photosensitive spots sensitive to ambient temperature, each connected to a row conductor and a column conductor. The photosensitive spots are connected by their conductors to a read circuit. The photosensitive spots are divided into detecting photosensitive spots to be exposed to light information corresponding to the image to be detected, the read circuits associated with these photosensitive spots each delivering a measurement voltage representative of the image to be detected, and into blind photosensitive spots protected from the light information, the read circuits associated with these blind photosensitive spots each delivering a dark voltage serving for temperature compensation. During detection of an image the dark voltages are picked up, then an average correction value from the dark voltages coming from one or more detected images is generated, and the average correction value is used to generate a correction voltage to be applied, during detection of a subsequent image, to the read circuits associated with the detecting photosensitive spots so that they deliver a measurement voltage made substantially independent of temperature. Such a method and device may find application in particular to radiological image detectors.

Method for temperature compensation of an image detector

A drive process for an array of photosensitive points produced on a semiconductor material. Each of the points has a photodiode connected in series with a switch element. The photodiode is reverse-biased and produces charges when it is exposed to a light signal during an imaging phase. Before the imaging phase, the photosensitive points are illuminated with an additional light flux whose intensity causes the photodiode to conduct in the forward direction and then in applying a biasing pulse to the photosensitive points in order to return the photodiode to reverse bias. Thus, a current is produced which has the effect of reducing a remanence effect in the semiconductor material.

Method for controlling a photosensitive device with low image retention, and photosensitive device implementing same

A circuit for reading charges injected at an input of the circuit including a read MOS transistor having first and second electrodes corresponding to a drain-source pair and for reading charges having a first polarity that are injected at the input of the circuit. The read MOS transistor is controlled by a control voltage that varies in a manner substantially inversely proportional to an input voltage of the circuit. Also included is an integration capacitor mounted between the first electrode of the read MOS transistor and a reference potential in which the input of the circuit is at the second electrode of the read MOS transistor, a charge detector for detecting charges having a second polarity that is opposite to the first polarity that are injected at the input of the circuit, and an imposing mechanism for imposing on the input voltage of the circuit, after the charge detector detects the charges having the second polarity, an equilibrium value equal to or close to a basic value that it takes between two successive operations of integrating charges with the first polarity so as to prevent a prolonged blocking of the read MOS transistor when charges having the first polarity arrive at the input of the circuit.

Charge-reading circuit protected against overloads coming from charges with undesirable polarity

A photosensitive device comprises: photosensitive cells located at the intersection of at least one addressing conductor and one read conductor, a cell comprising a photosensitive diode connected to a read conductor and to at least one diode having a switching function connected to an addressing conductor, these diodes having a common point; addressing means connected to at least one addressing conductor; charge-reading means connected to at least one read conductor. The device furthermore comprises first measurement means capable of the measurement, in real time, of an information element representing a current flowing in at least one addressing conductor, this conductor being taken to an idle potential during the illumination so as to be capable of quantifying the illumination received by the cells located on the conductor concerned by the measurement; and second measurement means capable of the measurement of an information element representing a current flowing, during the illumination, in at least one read conductor, this read conductor being taken, during the illumination, to a specific potential so as to be capable of quantifying the illumination received by the cells located on the conductor concerned by the measurement. Application especially to the detection of radiological images.

Photosensitive device equipped with an illumination measurement device

An integrator circuit for photogenerated charges which limits linearity defects. The circuit includes an integration capacitor with a first blade connected to a reference potential and a second blade having a variable potential which receives photogenerated charges. The circuit also includes a resetting MOS transistor of a first type connected to the variable potential at one terminal and to a supply potential on another. The MOS transistor represents a straight capacitance in parallel with the integration capacitor. One or more MOS transistors of a second type are connected to the variable potential and each have a stray capacitance in parallel with the integration capacitor. A variation in the voltage across the terminals of the integration capacitor causes a variation in the value of the straight capacitances of the MOS transistors of the second type which tends to compensate for the variation in the stray capacitance of the MOS transistor of the first type.

Circuit for integrating light-induced charges with improved linearity

A device for copying a voltage (Ve) comprises a pair of series-connected MOS transistors, their sources forming a common point. The voltage (Ve) to be copied is applied between the gate of the first MOS transistor of the pair and a reference. Means are provided to inject a flux of electrons at a common point. A storage capacitor has a first terminal connected to the drain of the second MOS transistor and a second terminal designed to be biased. Means dictate a potential at the drain of the second MOS transistor and then let it vary so that the flux of electrons is stored in the storage capacitor while at the same time decreasing in the second MOS transistor to the benefit of the first one. The copied voltage Vs is available, after stabilization, between the first terminal of the storage capacitor and the reference. Application in particular to circuits for the reading of charges generated in a photosensitive matrix or photosensitive linear array.

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Voiron, France

Thierry Ducourant