E2v Technologies (uk) Limited

Ev2 Technologies (uk) Limited

E2v Technologies Limited

Ian Moody

Raymond Thomas Bell

Kevin Hadfield

Martin Fryer

An imaging apparatus for x-rays includes a scintillator, overlying an array of imaging pixels on a substrate, and at least one trigger pixel array externally peripheral to the array of imaging pixels on the substrate such that the trigger pixel array is not substantially overshadowed by the scintillator from incident x-ray radiation. A layer substantially impervious to light but transparent to x-rays overlays the trigger pixel array, such that the trigger pixels are unresponsive to light but triggered by direct hits from incident x-ray photons.

Imaging apparatus

A photoelectric sensor array is labelled by accumulating charge, preferably charge from a dark current, in at least a portion of the sensor array and reading out the accumulated charge to form an image to determine locations of atypical pixels in the portion of the sensor array. A signature of the sensor array is generated from the locations of atypical pixels and stored. The array is subsequently identified by re-accumulating charge in the portion of the array to form a signature based on the atypical pixels for comparison with the stored signature.

Identification of a photoelectric sensor array

Effective sensitivity of a photodetector of an image sensor is controlled by partitioning signal charge from incident photons, thus producing a manageable yield and a consequently higher, photon shot noise limited, signal to noise ratio than in the prior art, when imaging high flux rates of energetic photons or particles, such as produced by x-ray generators. The invention may be applied, for example, to an image sensor with a photosensitive layer coupled to a charge collection/readout structure, e.g. photoconductor or scintillator on CMOS array, or to an intrinsically sensitive charge collection/readout structure, e.g. deep active layer CMOS. A radiation sensor pixel structurefor use in the invention includes a photodetector, a transfer gatefor controlling charge collection from the photodetector and a dump draincontrolled by a dump gate, arranged for selectively dumping charge to the dump drain means and collecting charge from the photodetector means, in a duty cycle, for varying effective sensitivity of the pixel structure. An image sensor containing such pixel structures may selectively be operated in an integration mode or a photon counting mode. Preferably the image sensor has imaging pixels and control circuitry arranged on a same semiconductor die, such as a CMOS semiconductor die.

Image sensor

An energy selective radiation sensor has a photodetector and a transfer gate for controlling transfer of charge from the photodetector to a first sense node. A first readout circuit is provided for reading out charge from the first node. In use a first charge accumulated in the photodetector from a first predetermined portion of an energy spectrum of a radiation source is transferred to the first sense node. A second charge is accumulated in the photodetector from a second predetermined portion of the energy spectrum. The first charge is readout from the first sense node with the readout circuit, the second charge transferred to the first sense node and likewise readout. In embodiments of the invention, a second sense node and second transfer gate are provided and the first charge is read out through a first sense node and the second charge through the second sense node. In further embodiments a dump drain controlled by a dump gate is also provided to permit duty cycle control of sensitivity of the photodetector by selectively dumping and storing of charge accumulated in the photodetector.

Radiation sensor

In a size determining system, a number of pixels in a dimension of a sensor array of photoelectric devices is determined. A readout register is arranged to receive charge accumulated in the dimension of the sensor array. A clock is connected to apply clock cycle pulses to the readout register to read out the charge from the readout register for a predetermined number of clock cycles known to exceed a supposed maximum number of pixels in the dimension of the sensor array. A discontinuity detector is operative to determine a first discontinuity in the readout charge, representing a last active pixel in the dimension of the sensor array. A counter is arranged to count clock cycles between a first active pixel and the first discontinuity to determine a number of active pixels in the dimension of the sensor array.

System for identifying a photoelectric sensor array size having a detector for determining discontinuity in the readout charge from a readout register

An x-ray sensorincludes a phosphorescent phosphorsusceptible to x-ray irradiationfor forming an image in the phosphor, the phosphor having a decay periodpersistent after an irradiation period. A photoelectric sensor arrayis arranged to receive phosphorescent emission from the phosphorescent phosphorcorresponding to the image. The photoelectric sensor array is gated off for a gated periodduring at least some of, or exceeding, the irradiation periodto dump output from the photoelectric sensor array means generated during at least some of the irradiation period to reduce the effect of direct x-ray irradiation of the photoelectric sensor array. A signal is at least primarily output from the sensor from persisting phosphorescence from the phosphor during the decay period.

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Chelmsford, United Kingdom

Ian Moody