| 摘要 |
This installation makes it possible to output a tube voltage V, a filament current I and a signal with duration of exposure t, the filament current and the duration of exposure being controlled conjointly as a function of a displayed tube voltage VTHT, a displayed filament current (I displayed) and a displayed duration of exposure (t displayed). According to the invention, it comprises: - means 21 for producing a numerical combination T, F representing the type of tube employed and, if appropriate, the focus of this tube which is used, - first digital means of determination 60 giving, as a function of this numerical combination and of the displayed tube voltage, a numerical value of maximum admissible filament current suited to the tube used and to the chosen focus, - means 70 for comparing this maximum filament current with the displayed filament current and for selecting a value of root-mean-square filament current equal to the smaller of these two values of filament current, - second digital means of determination 90 giving, as a function of this root-mean-square filament current, of the displayed tube voltage and of the numerical combination representing the tube used and the chosen focus, the maximum admissible duration of exposure suited to the tube used and to the chosen focus, and - second comparator means 100 for comparing this maximum duration of exposure to the displayed duration of exposure and for selecting a value of root-mean-square duration of exposure equal to the smaller of these two values of duration of exposure. <IMAGE>
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