Patent ID: 8680428

Claim:
A slit width adjusting device comprising: a pair of slit members which is parallel to each other, and which is moved so as to approach each other or to be separated from each other in order to adjust a slit width of the pair of slit members; a driving section to move the pair of slit members in a direction so as to approach each other or in a direction so as to be separated from each other; an absolute position original point detection section to detect an arbitrary absolute position of at least one of the pair of slit members as an original point, the absolute position original point detection section including: a main body section disposed in a fixed position with respect to the driving section, the main body section including a fixed scale disposed in the main body section, and a moving unit connected to one end of a spindle, a longitudinal axis of the spindle being oriented in a direction of movement of the slit members, the other end of the spindle moving integrally with movement of the at least one of the pair of slit members driven by the driving section, the arbitrary absolute position of the at least one of the pair of slit members being detected as the original point by comparing a position of the moving unit with respect to the fixed scale; and an adjustment section to adjust the slit width by controlling a driving of the driving section, wherein the adjustment section comprises: a storage unit to store a slit width table in which a displacement amount of the slit width from the original point, and a drive instruction value of the driving section corresponding to the displacement amount of the slit width from the original point, are corresponding to each other; and a drive control unit to instruct the storage unit to extract the drive instruction value of the driving section corresponding to a specified slit width, so as to drive the driving section according to the extracted drive instruction value.