Patent ID: 8189743

Claim:
A blade device for use in forming a hollow cone-like radiation, the blade device comprising: a pair of first blade members opposed to each other symmetrically at a fixed inclination angle in a first direction perpendicular to an axis of the cone; a pair of second blade members opposed to each other symmetrically at a variable inclination angle in a second direction perpendicular to the axis of the cone, the second direction perpendicular to the first direction; a pair of lever members each fixed respectively at a first end thereof to a respective face of each the pair of second blade members on the side opposite to a mutually confronting side; and a lever actuating unit configured to pivot the pair of lever members about respective support shafts, wherein the lever actuating unit comprises: a pair of shaft members supported axially movably and unrotatably, the pair of shaft members having outer peripheries formed with thread grooves respectively and being engaged at front end portions thereof with a second end of each of the pair of lever members respectively; a pair of wheels supported axially unmovably and rotatably, the pair of wheels having inner peripheries formed with thread grooves respectively and being threadedly engaged with the pair of shafts respectively; a common entraining member engaged with the pair of wheels; and a driving wheel configured to drive the entraining member.