Teledyne E2v Semiconductors Sas

Teledyne E2v Semiconductor Sas

Caroline Papaix

Pierre Fereyre

Florian Julien

Stéphane Gesset

Nathalie Pascal

Christine Charrat

Stéphane Crespin

Raphaël Neri

The subject matter of the invention is an active pixel dental radiological image sensor, with integrated X-ray occurrence detection, which uses the pixels of the matrix to detect the start of an X-ray flash, by detecting the current produced by all the photodiodes in the matrix. A switching circuit MUXthus allows, in a first phase of detecting the start of an X-ray flash, a common connection node NC to be connected that corresponds to the drain of a photodiode initialisation transistor Mat the input of a current-voltage conversion detection circuit DTX, which provides as output a signal for detecting the start of an X-ray flash when the current produced by all the photodiodes of the matrix exceeds a predetermined threshold. The switching circuit MUXis then controlled to connect the common connection node NC of the pixels to a photodiode re-initialisation voltage source, VRS. In an alternative embodiment, some pixels of the matrix can be used to detect the end of an X-ray flash using the same principle, by injecting the current produced by the photodiodes of these pixels that is collected on a different common connection node, electrically isolated from the first, with the end of flash signal corresponding to a variation in this current, which falls below a predetermined threshold. The active pixels can be of the three or more transistor type, in particular with five and more transistors.

Active pixel intraoral radiological image sensor and associated image capture method

A circuit () for detecting the appearance of x-rays with a view to triggering a radiological image capture, comprising a set () of photodiodes that is connected to a ground (G), an amplifying circuit () and a capacitor (C), the amplifying circuit () comprising an amplifier (AMP) and a voltage source (GEN) and being connected, via a first input, to the output of the set () of photodiodes, the capacitor (C) being connected between the ground (G) and a second input of the amplifier (AMP), the detecting circuit () being characterized in that the amplifying circuit () is configured to carry out in succession the steps of:

X-ray detection circuit for a dental radiology sensor

The invention relates to medical imaging and, more specifically, to intraoral dental radiology. The sensor according to the invention includes a series (SPHx) of detection photodiodes for detecting the arrival of an X-ray flash. The series of photodiodes occupies the location of a central column of the matrix of pixels. The signal of the missing pixel in each row can be reconstructed by interpolating the signals provided by the adjacent pixels of the row. The detection photodiodes are identical to the photodiodes of the active CMOS pixels. They are all electrically connected on one side to a reference potential and on the other side to a detection conductor (CD) extending along the series of photodiodes. This detection conductor is connected to a detection circuit (DX) delivering a signal for triggering the capture of an image when the detected current or the variation in this current exceeds a threshold showing that an X-ray flash has been initiated.

Radiation sensor with X-ray detection

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Quaix-en-Chartreuse, France

Caroline Papaix