| 摘要 |
1501610 Radiographic apparatus PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 21 Feb 1975 [26 Feb 1974] 7358/75 Heading H5R The control system of an X-ray image unit with sheet film changer moves the film and diaphragms to expose the whole film, or right or left half, or quarters; double exposure is inhibited by a register of exposed sections comprising four bi-stable circuits 1, 2, 3, 4. Initially all four have zero output, allowing all sections to be exposed; after exposure the corresponding output is set by the attached circuit to voltage L. The bi-stable circuits are all supplied with a voltage L from line 5 immediately after any exposure; they will change their output to L if their 'condition' inputs, immediately above the respective line 5 inputs, are simultaneously at L; for 1 the condition is permanently L. Gates 21, 31, 41 are OR, while 7, 34, 43, 44 are AND; 33 is a negating device. When outputs 32 AND 42 are both L, gate 7 initiates automatic film change, after which a clearing signal on line 8 resets all outputs to 0. If all four quarters are to be exposed simultaneously (survey exposure), line 6 is set at L; for a left or right pair (oesophagus exposure), line 9 is set at L; for quarter field exposure (stomach) neither 6 nor 9 is energized. With all outputs at 0 and line 6 energized, initiation of exposure exposes all four quarters; the subsequent signal on line 5 sets 12 to L which via OR gate 21 sets 22 to L; this via OR gate 31 sets 32 to L and the combined outputs from 22 and 32 via AND gate 44 and OR gate 41 set 42 to L; 32 and 42 then via AND gate 7 initiate film change and clearing. If line 9 is energized but not 6, with all outputs at 0 initiation of exposure causes fields F I and F3 to be exposed simultaneously; the output of negating device 33 and line 9 being both at L, so that bi-stable circuits 1 and 3 change their outputs to L immediately on receipt of the line 5 signal after exposure. On the next exposure fields F2 and F4 are exposed together, and the following signal on line 5 sets to L output 22 via OR gate 21 and output 42 via AND gate 43 and OR gate 41. All outputs are now L and 32 and 42 combine to initiate film change and clearing. Similar logic applies when two quarters are exposed together before or after two single quarters or all four quarters are exposed separately. |
