Abstract: 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.

Abstract: A grid for an electron tube with an axial beam which includes an apertured part through which the electrons of the beam are intended to pass. The grid is in the form of a bell and is made of a single material. The apertured part is located at the top of the bell but is placed in the bottom of a hollow so that the electrons passing through the grid around its periphery are focused onto the axis. Such a grid may find particular application to IOT-type tubes.

Abstract: An image detector using arrays of photodiodes, and in particular to a radiological image detector. In the image detector, all the photodiodes of one and the same array are linked to adapter amplifiers embodied in the form of at least one integrated circuit. In each integrated circuit, an adapter amplifier, to which no photodiode is linked, delivers a voltage serving as a reference to define a bias voltage to be applied to the photodiodes. This arrangement makes it possible in particular to associate photosensitive arrays with amplifiers exhibiting different voltage thresholds.

Abstract: A control process for addressing an AC plasma panel. The panel includes line electrodes crossed with column electrodes where the intersections of these electrodes define cells. Sustain signals are applied to all of the line electrodes by way of at least one control circuit. The cells are addressed by superimposing supplementary voltage porches onto the sustain signals and then subsequently superimposing addresses pulses onto the supplementary porches. This method makes it possible to reduce the amplitude of the addressing pulses, thus resulting in a lesser demand on the control circuits resulting in a reduction of capacitive consumption.

Abstract: A microwave modulable field-effect cathode which includes at least one array of emissive tips. A microwave modulation signal is produced by a device including a microwave-controllable semiconductor modulation element which is close to the tip array, and a short microline for conveying the modulation signal to the tip array. The microline provides impedance matching between the tip array and the semiconductor modulation element. Such a device can find application as a compact field-effect cathode, as one example.

Abstract: A device for measuring the exposure of a solid-state image detector. The image detector includes a first face exposed to ionising radiation representative of the image. The device also lets unabsorbed ionising radiation exit through a second face opposite the first face. The measuring device is configured to be placed close to the second face and to be exposed to the unabsorbed ionising radiation. The device includes at least one optical fiber which emits visible or near visible radiation, obtained by conversion in the optical fiber, towards at least one detection device, the visible or near-visible radiation being representative of the unabsorbed ionising radiation. The detection device produces a signal representative of the exposure of the image detector. Such a device may find particular application to radiology image detectors.

Abstract: A multibeam electron tube with several approximately parallel electron beams passing through a body. Among the beams, at least some define an interbeam volume, each beam defining the interbeam volume being subjected to a perturbing azimuthal magnetic field induced by all the other beams. The tube includes an element allowing, in at least one conducting element located in the interbeam volume, flow of a reverse current in the opposite direction to that of the current of the beams, this reverse current generating, in the beams defining the interbeam space, a magnetic correction field whose purpose is to oppose the perturbing magnetic field. Exemplary embodiments of the present invention especially apply to the multibeam klystrons or traveling wave tubes.

Abstract: A traveling wave tube designed to operate as an amplifier within plural frequency bands, which includes a microwave line through which electrons travel and in which a signal is amplified. The microwave line includes, in succession, an input section separated from a succession of gapped output sections, each output section working within one of the operating frequency bands of the traveling wave tube. The input section, connected at one end to an input for injecting the signal to be amplified, works within a frequency band encompassing the operating frequency bands of the traveling wave tube and is intended to preamplify the signal to be amplified. The succession of output sections receives the preamplified signal, each of the output sections being intended to amplify it if the signal is at a frequency lying within its working frequency band and to let it pass through virtually without any interaction if it is at a frequency outside its working frequency band.

Abstract: A process for leaktight sealing of a solid-state X-radiation detector. The detector includes an amorphous silicon detecting slab and a layer of scintillating substance. The slab has peripheral connection zones formed by the flexing of an anisotropic conducting film on the ends of conductive tracks arranged on the slab and external conductors. The flexing zone and at least the periphery of the scintillating layer are covered with an uninterrupted layer of impermeable material, for example by screen printing.

Abstract: In order to solve an analogue/digital conversion dynamic swing problem encountered with detectors, especially solid-state detectors, of a tomodensitometer, there is provision to operate converters at a greater frequency, that is to say more often. In doing this, the converters used need not have as large a conversion dynamic swing. It is shown that instead of a 20-bit conversion, one can make do with a 14-bit conversion. The various conversions are added together to construct the signal. The measurement is thereafter switched, by way of improvement, as a function of the level of the signal received. This measurement is performed according to one mode of use or another, in which modes this acceleration of the rate of analogue/digital conversion is or is not effected.

Abstract: A process for producing a radiation detector. A plurality of unitary elementary slabs are assembled on a positioning support. The slabs are adhesively bonded onto the common support. The bonding is carried out in two successive steps: a first step for sealing the inter-slab spaces without filling them entirely, and a second step intended to spread a film of adhesive over the entire surface of the assembled slabs. A subsequent step includes fitting the common support.

Abstract: To solve a control complexity problem encountered with very numerous detectors of a tomodensitometer, there is provision to group the detectors into groups and to subject all the detectors of a group to the same processing. By way of improvement, the determination of the mode of processing is performed during a view, and the processing is applied to the signals detected during a subsequent view.

Abstract: The disclosure relates to a radiofrequency generator including an Inductive Output Tube with an electron gun followed by an anode, the gun being raised to a high voltage in use, means producing an input radiofrequency signal and means of transmitting it to said IOT such that it provides an output signal whose power is amplified compared to said input signal, wherein said means producing said input radiofrequency signal, said means transmitting it to said IOT and said gun are confined in an electrostatically screened enclosure that is electrically isolated from the potential of the anode and can be raised to a high voltage, said gun receiving its high voltage from said screened enclosure. The invention is applicable to very high power radiofrequency generators.

Abstract: 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.

Abstract: To reduce phenomena of distortion in an image intensifier tube, it is planned to provide its input with a permanent test pattern. The image of the test pattern is then read in real time and a deduction is made therefrom of the correction to be made to an image transmitted and converted by this intensifier tube. To create a permanent test pattern, references are made on the intensifier tube, on its input window. As a variant, the references are produced by an auxiliary laser source that illuminates the cathode of the tube by the rear.

Abstract: In a method for adjusting the overall luminosity of at least a part of a matrix screen, each row of the part is processed several times non-periodically to display half-tones. Each processing consists of a semi-selective operation followed by a selective operation. A delay is planned between the selective operation and the semi-selective operation, this delay being proportional to a weighting factor that is adjustable as a function of the desired overall luminosity and proportional to the time interval between the beginning of the treatment in progress and the beginning of the next treatment.

Abstract: A frequency tuning device for a microwave tube. The tube has one or more resonant cavities which are tuned with the aid of a movable tuning element for each cavity. Each tuning element has an actuating device and a sensor which detects the position of the tuning element. An electronic control is provided for comparing the position of the tuning element supplied by the sensor with a set position and for delivering a control signal to the actuating device which moves the tuning element to the set position.

Abstract: Disclosed is an improvement in image converter tubes that convert the X-ray image given by their input screen into a visible image. Stray glimmer develops on the insulators inside these tubes and the disclosure makes it possible to eliminate this glimmer by the deposition, on the insulators, of a thin layer of a product such as diamond-like carbon having a low secondary electron emission rate. Metal oxides are also suitable for this purpose. Application to image intensifiers.

Abstract: The disclosure relates to electron guns comprising several electrodes, including a plurality of cathodes designed for the production, from an emissive face, of an electron beam each. Each of the cathodes is surrounded by a pole piece. This pole piece is designed to convey a magnetic flux close to the emissive face of the cathode. Application to longitudinal-interaction multibeam electron tubes.

Abstract: A color two substrate alternating plasma display panel. The panel includes two tiles joined together so as to be opposite each other and defining a space therebetween. The space is filled with gas. One of the tiles has column electrodes which are approximately parallel, separated by a spacing and covered with at least one phosphor region. The other tile has at least one row electrode. The phosphor regions are provided with at least one recess placed at the intersection of a column electrode with the row electrode. A color pixel is formed by neighboring recesses lying within the same row electrode in adjacent phosphor regions. In order to obtain better light efficiency, the distance separating two adjacent recesses lying within adjacent phosphor regions and belonging to the same pixel is greater than the spacing so that space has a thickness greater than that required when two recesses are separated by approximately the spacing.