| 摘要 |
The invention relates to an X-ray radiographic unit having at least one adjustable diaphragm plate (4, 5) near the film and limiting the radiation field (3), and a marking disc (14), which is rotatably mounted at a prescribed distance from the edge (16) of the diaphragm plate that limits the radiation field, and has data which are provided on its circumference and can be imaged by means of X-rays. In X-ray radiographic units, a slight enlargement of the film/object separation is enough to entail a marked reduction in the detectability of details. Consequently, the aim is to design the marking disc to be as flat as possible. The invention provides for this purpose that the diaphragm plate supports at a distance from its edge (16) limiting the radiation field, which edge is smaller than half the diameter of the marking disc (14), an axle (15) which is aligned parallel to its surface normal and on which the marking disc can be rotated via a cable drive. The cable (17) is wound over a cable drum which can be displaced by the diaphragm plate on a drive shaft (20) permanently installed in the housing (1) of the radiographic unit. An X-ray radiographic unit according to the invention is suitable, in particular, for use in X-ray examination units.
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