JPS57202700A - Device for automatic exposure to x-rays - Google Patents

Abstract

PURPOSE:To execute optimal exposure to X-rays, by providing a multiple light intake section at the side of the output of an image intensifier to detect the shortage and excess of the exposure to X-rays and by removing outputs based on the detected shortage and excess, to determine an optimal light intake field of vision to maintain said field throughout the stoppage of seeing-through and throughout photographing. CONSTITUTION:An examined body 2 is exposed to X-rays from an X-ray tube 1. The shortage and excess of the exposure are detected through a multiple light intake section 11 provided at the side of the output of an image intensifier 4 and are latched at 23. For seeing-through, a changeover unit 31 is connected to a comparator 32 to automatically adjust the seeing-through conditions and another changeover unit 36 is put in its positon of X-ray exposure. When a seeing-through switch 38 is turned on, a gate 34 is opened to apply the output of a changeover signal generator 33 to a selector 12 to remove light intake fields of vision based on the channels of the shortage and excess. A switch 37 is then turned on through a delay circuit 35 to perform the seeing-through. When the seeing-through switch 38 is turned off, the gate 34 is closed to maintain the last conditions of the seeing-through and the irradiation of the X-rays is stopped through the delay circuit 35. After that, the changeover units 31, 36 are shifted to their positions of photographing and the switches 37, 39 are turned on, so that optimal exposure is effected through a phototimer 6.