| 摘要 |
PROBLEM TO BE SOLVED: To provide a radiographic instrument in which a plurality of phototimer photocell parts are automatically selected simply when a subject touches an imaging table while taking an imaging position. SOLUTION: When a subject 3 touches a touch panel 4 while taking an imaging position, its signal urges the CPU of a touch panel controller 17 to compute X-Y coordinates to recognize a contact surface and to select an optimum phototimer photocell part from a plurality of phototimer photocell parts while automatically switching a selector switch 18 to start imaging. X-rays from an X-ray tube 1 are constricted by a collimator 2, are transmitted through the subject 3 as scattered rays are eliminated by a grid 6, and converted into an optical image by a fluoroscopic plate 7. Only a specific portion of light emitted through lead glass is captured by the phototimer photocell part 5 and its electric signals are integrated by an integrating capacitor 12, with its voltage and the reference voltage of a density setter 14 both inputted to a comparator 13; when both of the voltages are the same, a high-voltage shutoff signal is fed to a switch 15 to shut off the high voltage of an X-ray high voltage generator 16 to stop X-ray radiation, thus making it possible to take radiograph at the optimum density.
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