| 摘要 |
PROBLEM TO BE SOLVED: To drastically extend durability by switching the conductive contactor of a grounding unit to a contact/non-contact with a rotary member. SOLUTION: A grounding unit 54 consists of a grounding pad 52 as a contact, a support spring 53 as a support member, and an actuator 57 as a switching means. Then, an eccentricity cam 56 is provided at an output shaft 57a of the actuator 57 being provided between the grounding pad 52 and a fixing part 60. Then, when air is introduced to a suction hole 58, a suction hole 59 becomes an exhaust hole, the output shaft 57a rotates by 90 degrees in a specific direction for retaining the eccentricity cam 56 so that it does not touch the support spring 53. Then, when air is introduced into the suction hole 59, the suction hole 58 becomes an exhaust hole, the output shaft 57a rotates by 90 degrees in a direction opposite to the rotary direction for retaining so that the eccentricity cam 56 can be brought into contact with the support spring 53, thus reducing the generation of the wear powder of a contact and hence drastically extending durability.
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