US 4,906,855 AGranted

Photosensitive matrix with two diodes per dot without specific resetting conductor

AssigneeThomson-CSF

InventorsJean-Luc Berger, Marc Arques

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Abstract

The disclosure concerns matrices of photosensitive elements. To prevent the need for a resetting light source in matrices using, as a photosensitive dot, a photodiode in series with a capacitor between a row conductor and a column conductor, a photosensitive dot is proposed, formed by a photodiode in series with a reading diode between a row conductor and a column conductor, it being possible to put the reading diode into forward or reverse conduction. To read the photoelectrical charges generated, a reading pulse, which makes the reading diode forward conductive, is applied. To then reset the potential of the floating node A, at which the photoelectrical charges accumulate, at a constant starting level, a reverse resetting pulse is applied, thus making the reading diode conductive (but this time in reverse conduction).

Claims10

Dependent claims

A matrix of photorensitive dots comprising a network of photosensitive dots arranged in rows (at least one row) and columns (at least one column), each photosensitive dot being located at the intersection of a row and a column, wherein each photosensitive dot comprises a photosensitive element in series with a reading diode between a row conductor and a column conductor, the reading diode having a first forward turn-on voltage threshold (Vsd) and a second reverse turn-on voltage threshold (Vsi), the matrix further comprising, for the reading of the charges that have collected at the junction point of the photosensitive element and the reading diode, a means to apply the following to the row conductor:

firstly, a steady raference voltage (Vp) level to the row conductor during a charge integration stage;
then a voltage pulse, with a first sign, called a reading pulse;
finally, a voltage pulse, of the opposite sign, called the resettnng pulse, the amplitude (VL1-VL2) of the difference between the voltage levels of the reading pulse and the resetting pulse being greater, in absolute value, than the difference between the forward turn-on voltage and reverse turn-on voltage thresholds for the reading diode.

Dependencies are inferred from the claim text.