| 主权项 |
1. A head circumference adjustment device of a helmet, comprising:
a main body formed with a substantially enclosed cavity, the cavity being bounded by a peripheral wall and a bottom section, multiple toothed sections being formed on an inner circumference of the peripheral wall about the cavity, the main body defining first and second slots communicating with the cavity; a strap having a transversely narrowed first end portion and a transversely narrowed second end portion each configured for insert through one of the first and second slots into the cavity, each of the first and second ends portions being formed with a rack section extending from a shoulder section to terminate at a thumb section, wherein the thumb section is located at a distal end of each of the first and second portions and extends with a greater transverse width than the rack section, the rack section being formed with a toothed outer edge, each shoulder section being configured to retentively engage a stop section formed on the main body for limiting entry into the cavity of one of the first and second end portions of the strap, each thumb section being configured to retentively engage a restriction section formed on the main body for preventing escape of one of the first and second end portions of the strap from the cavity; and a controller displaceably mounted in the cavity for selectively engaging the toothed sections of the cavity, the controller having at least one cantilever and a gear engaged with the rack sections of the strap, wherein responsive to rotating the controller, the rack sections are driven to move the first and second end portions of the strap. |
