Slit radiography apparatus
AssigneeN.V. Optische Industrie "De Oude Delft"
InventorRonald J. Geluk
Life of this patent
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Abstract
A slit radiography apparatus is provided with an absorption device comprising electrically controllable piezoelectric tongues. Upper and/or lower deflections of the tongues are limited to a maximum by trips outside the X-ray fan beam. More than one strip can be present as seen in the length direction from the fixed ends of the tongues Thus deflections of the tongues are limited and great phase changes in the control signals without resultant oscillations can take place during the time the tongue are restricted in their movement by the strip.
Claims11
A slit radiography apparatus comprising an X-ray source (1), an X-ray detector (10) for sensing radiation passing through a body (4) to be radiographed, a slit diaphragm (2) positioned between said X-ray source (1) and said body (4) for forming a substantially planar X-ray beam (3), means for scanning (7) said body (4) with said planar X-ray beam (3) in a direction (5) transverse to a longitudinal direction of a slit (17) of said slit diaphragm (2), an absorption device comprising a plurality of electrically controllable piezoelectric tongues (9, 15) positioned along said longitudinal direction of said slit (17) forming a corresponding number of sections of said planar X-ray beam (3), each of said tongues (9,15) having a fixed end and a free end, a control device (11) for feeding electrical control signals to said tongues (9, 15) having a fixed end and a free end, a control device (11) for feeding electrical control signals to said tongues (9, 15) for continuous vibration thereof at a predetermined frequency characterized by at least one stop element (31, 32;
- 35, . . . , 40;
- 40a, 41;
- 50, 51, 56, 57) for limiting the maximum. deflections of at least a number of said tongues (9, 15), by said control signals being of such magnitude that said tongues (9, 15) are limited in their deflections by said at least one stop element (31, 32;
- 35, . . . , 40;
- 40a, 41;
- 50, 51, 56, 57) for at least part of the time of any vibration period and by means (11) for changing phases of said electrical control signals during said part of the time of said vibration periods.
Method for operating a slit radiography apparatus provided with an absorption device (8) which interacts with a slit diaphragm (2) and which comprises electrically controllable piezoelectric tongues (9, 15), each having a fixed end and a free end and a control device (11) which feeds electrical control signals to said tongues (9,15) during operation, said method comprising feeding control signals to said tongues (9, 15) for continuous vibration thereof at a predetermined frequency and changing phases of said control signals characterized in providing stop elements (31, 32;
- 35, . . . , 40;
- 40a, 41;
- 50, 51, 56, 57) for limiting maximum deflections of said tongues (9, 15), controlling said control signals to be of such magnitudes that said free ends are limited in their deflections by said stop elements (31, 32;
- 35, . . . , 40;
- 40a, 41;
- 50, 51, 56, 57) and in changing phases of said control signals during the time periods that said free ends are deflected against said stop elements (31, 32;
- 35, . . . , 40;
- 40a, 41;
- 50, 51, 56, 57).
Dependencies are inferred from the claim text.