Driving unit for sampling devices

Claim 1

Driving unit for a device for taking tissue samples, said device in addition to the driving unit (1) comprising a guide sleeve to which is mounted a needle unit consisting of two sequentially arranged needle holders (4a, 4b) carrying respectively an outer (7a) needle and, slidably disposed therein, an inner needle (7b) having a cavity near its tip, said needle holders being shiftable in relation to each other longitudinally, and adapted to be pre-tensioned in the same direction for propelling said needles (7a, 7b) by means of one spring (5a, 5b) each, said driving unit (1) comprising a drive (4b, 5b, 7b, 24) for propelling said inner needle (7b) and a drive (4a 5a 7a 23) for propelling said outer needle (7a) each of said drives being provided with a spring mechanism adapted to be pretensioned, and a tensioning device (31a 31b) for pretensioning the spring mechanism, the drive for the inner needle further being provided with a triggering device (6) to be actuated from outside of the unit for releasing said drives in such a way that the inner needle is first extended out of the outer needle followed by the outer needle resecting and covering a tissue sample in said cavity, the needle holders (4a, 4b) being provided with releasable locking means (33a, 33b) performing the locking function in cooperation with elements (23,24) provided in said guide sleeve (3) the triggering device (6) being adapted to be manually operated for releasing the needle holder (4b) of the inner needle (7b) which in turn is adapted to release during the final phase of its propulsion the needle holder (4a) of the outer needle (7a), the needle holders (4a, 4b) being pre-tensioned against the action of the springs to a position in which the locking means (33a, 33b) in question is locked by cooperation with the respective elements (23, 24), characterized in that a tensioning sleeve (2) rotatably surrounds said guide sleeve (3), and that the inside of the tensioning sleeve (2) is provided with cam profiles (11, 12) cooperating with the needle holders (4a, 4b) in such a way that during rotation of the sleeves (2, 3) in relation to each other, said pre-tensioning of the needle holders (4a, 4b) takes place.