Thomson-csf

Thomson-lsf

Jean L Berger

Jean L Coutures

Marc Arques

Louis Brissot

Roger Benoit-Gonin

Pierrick Descure

Yvon Cazaux

Pierre Descure

Yves Thenoz

Guy Moiroud

Sylvain Fontanes

Daniel Woehrn

Michel Bourrat

Yves Cazaux

Bruno Virando

In a matrix array of photosensitive elements, each photosensitive point is provided with a photosensitive element (pin photodiode) in series with a capacitor between a row lead and a column lead. It is proposed to make use of a simplified photosensitive element in which an end semiconductor layer is suppressed such as, for example, the n-layer of a pin photodiode or the n-layer of a five-layer phototransistor of the nipin type. The dielectric of the capacitor then comes directly into contact with an intrinsic semiconductor layer in which electrons accumulate. These electrons reconstitute the equivalent of an n-type doped layer.

Matrix of photosensitive elements associating a photodiode or a

The disclosure concerns photosensitive matrices, and especially those using NIPIN or PINIP type phototransistors made of amorphous silicon. To prevent problems of remanence, due to the collecting of holes in the base after an illumination stage, it is proposed to follow the step for reading the illumination signal by a remanence erasure step in which the phototransistor is made conductive in forward or reverse bias, so as to inject, into the base, electrons which will eliminate the holes by recombination. Switching on by reverse bias proves to be more efficient than switiching on by forward bias. The invention is applicable notably to a matrix structure of rows and columns of photosensitive sites in which each site is formed by a NIPIN transistor made of amorphous silicon in series with a reading diode that may be put into reverse conduction.

Method of photoelectric detection with reduction of remanence of a

Disclosed is a matrix of photosensitive elements for imaging. This matrix comprises, in series between a row conductor and a column conductor, a capacitor in series with a NIPIN or PINIP type phototransistor. This phototransistor can be made conductive, for the reading of the charges stored in the memory, as easily as a photodiode, even in darkness. The phototransistor is preferably formed by a stacking of N type, intrinsic type, P type, intrinisic type and N type semiconducting layers.

Matrix of photosensitive elements combining a phototransistor with a

When the capacitance of the conductive columns of the line-transfer photosensitive device is higher than that of the photosensitive elements and of the read register, use is made of a reading circuit provided in the case of each conductive column with a plurality of charge storage capacitors separated by an MOS transistor. These MOS transistors operate in the saturating mode and pass signal charges derived from each conductive column from one capacitor to the next up to the read register. The storage capacitors have decreasing values as the distance from the read register becomes shorter. Transfer of the signal charges is accompanied by transfer of polarization charge quantities which decrease in value as the distance from the register becomes shorter. Once the transfer operations have been performed, these quantities of polarization charges are returned to their initial capacitors.

Circuit for reading a line-transfer photosensitive device, a

An improved line-transfer photosensitive device and particularly a device which operates with a double drive charge comprises on at least one semiconductor substrate a photosensitive region made up of M lines of N photosensitive points. The photosensitive points of the different lines are connected in parallel by means of conductive columns to a line memory which carries out at least the transfer of the signal charges integrated on any one line of the phtosensitive region to a read register consisting of a charge-coupled shift register of the volume transfer type. The line memory is formed on a semiconductor substrate region having an impurity implantation of opposite type with respect to the substrate in order to produce a volume charge transfer. The region in which the line memory is formed has a dopant concentration which is lower than or equal to that of the region in which the shift register is formed.

Line-transfer photosensitive device

The present invention pertains to a large-sized X-ray photography panel. This panel comprises several modules placed end to end. Each module comprises a network of photosensitive detectors with the same number of columns as the panels but with a smaller number of rows. Each module has its own addressing and reading means. The addressing means are located on an edge of the insulating substrate that bears the detectors. The reading means are located on the other side of the substrate from the detectors. A screen, which is opaque to the radiation to be detected, is interposed between the substrate and these means. These means are liked to the column connections coming from the opposite side of the substrate by connections along one of the side surfaces of the substrate.

Panel for X-ray photography and method of manufacture

The invention provides a matrix of photosensitive elements in which each photosensitive element is reduced to the association of a diode and a capacity. The method for manufacture thereof is therefore easy particularly from amorphous silicon. The method for reading same uses multiplexed reading of the columns: the n columns are distributed in groups of n/M successive columns controlled simultaneously by M horizontal shift registers, each associated with a reading integrator. To ensure correct reading of the useful signal, whatever their level, the level of the voltages at the terminals of the diodes of the photosensitive elements is reset so that the starting voltage at the beginning of each reading pulse applied to a line is such that only this pulse, and even with a maximum useful illumination signal, can bias the diode forwardly, and so that with a column addressing pulse, the diode is biased forwardly even in the absence of the useful signal.

Matrix of photosensitive elements and an associated reading method in

A method for reading a photosensitive element having a photodiode and a capacitor as applicable in particular to reading a low-level analog signals consists in introducing a biasing charge background, for example by means of calibrated uniform illumination prior to each read operation in order to cause forward biasing of the photodiode substantially beyond its knee voltage at the time of application of a control read pulse which reliably restores the voltage at the photodiode terminals to the knee voltage value, the current during the read operation being such that all the charges are then reliably transmitted via the capacitor to the integrating read amplifier.

Method for reading a light-sensitive element constituted by a photodiode

An analog image memory device using charge transfer and comprising:

Analog image memory device using charge transfer

A multilinear charge transfer array is provided formed by N lines of P photosensitie detectors. Each photosensitive detector is connected directly by a connection to a demultiplexing and reading system, the signals obtained at the output of the array being fed to a processing device external to the array. The demultiplexing system comprises a charge transfer shift register with N.times.P stages, the connections between each detector and the corresponding input of the register being provided so that the detectors of the same rank are connected to contiguous inputs.

Multilinear charge transfer array

An analog accumulator used in association with a solid state image analyzer for averaging and storing the fixed pattern noise (FPN) includes an N-stage transfer shift register with an input receiving a signal corresponding to the fixed pattern noise and with N outputs, N floating storage diodes each connected to an output of the transfer shift register, N reading parts each connected to a floating storage diode and each comprising a floating input diode connected to the floating storage diode through an injection gate, an injection device and a charge removal drain, and an N-stage transfer shift register with N inputs each connected to a reading part and with an output. The accumulator provides M integrations of N samples of an analog signal and delivers, at the end of the M integrations, the N accumulated samples several times.

Analog accumulator

A charge transfer analog comparator comprising two adjacent MIS capacities coupled together by a passage gate and connected respectively to the input and to the output of an amplifier as well as the means for initializing the comparison connected to the input of an amplifier and means for introducing under each capacity respectively the signal charge and the reference charge.

Charge transfer analog comparator and devices using such a comparator

Use is made of a row memory and a read register, in which charge transfer takes place in volume. The threshold voltage of the negative feedback amplifiers is adjusted so that the operating point of the assembly constituted by each amplifier, the diode and the gate of the memory to which it is connected is located in the high gain zone of the transfer characteristic of the amplifier. It is possible to adjust the threshold voltage by an enhancement in its own type of impurities of the zone of the substrate located beneath the gate of one of the MOS transistors constituting the amplifier.

Photosensitive row transfer device provided with negative feedback

A non recursive analog integrator providing M integrations of a sampled analog signal Vn,m. The integrator comprises a series parallel demultiplexer with N outputs, N capacitors each with an electrode connected to a floating potential with respect to a reference potential, and a parallel series multiplexer with N inputs, the respective capacitors being connected in parallel between the outputs of the demultiplexer and the inputs of the multiplexer. Each capacitor performs, at each integration, the summation in form of charges of the sample of corresponding rank of the sampled analog signal Vn,m. So, at the end of the M integrations, an analog signal- ##EQU1## is obtained at the output of the multiplexer. Charge transfer devices serve as the series parallel demultiplexer and as the parallel series multiplexer.

Non-recursive analog integrator

A charge transfer multi-linear strip comprising several lines of photosensitive detectors, each line receiving successively the radiation to be detected and comprising charge transfer shift registers which provide in phase summing of the information collected at the detectors occupying the same position in the different lines, and wherein:

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Paris, France

Jean L Berger