Patent attributes
A seal belt includes inner and outer belt sections. The inner belt section revolves according to the movable member movement. The outer belt section includes, between the inner belt section and an opening, a first portion in which a first end is retained at a movable member inside section portion, the portion being closer to the opening lower end, and the remaining portion extends along the opening and is retained at a third space position, and a second portion in which a first end is retained at an inside section portion, the portion being closer to the lower end, and the remaining portion extends to a fourth space position along the opening and is retained at the fourth space position. The first portion and second portions lengths are changed in a complementary manner according to the movable member movement. The drive mechanism is surrounded by the inner belt section.
