Patent ID: 7174575

Claim:
A ratchet mechanism for a headband that has overlapping rear end portions, each rear end portion defining an elongated slot and associated rack gear, comprising: a housing including an outer substantially arc-shaped housing section joined to a inner substantially arc-shaped housing section, thus defining an internal cavity for receiving the overlapping rear end portions of said headband; and an adjustment mechanism substantially contained within the internal cavity defined by said housing sections and adapted to cause lateral movement of the overlapping rear end portions of said headband with respect to one another, said adjustment mechanism including an insert received and retained in one of said housing sections and having an inner circumferential surface that defines a ring gear, a rotational element contained within the internal cavity defined by said housing sections, said rotational element including a pinion which is adapted to mate with and engage the respective rack gears of the overlapping rear end portions of said headband, an adjustment knob secured to or integral with said rotational element such that rotation of the adjustment knob results in rotation of the rotational element, the pinion of the rotational element engaging the respective rack gears of the overlapping rear end portions of said headband and causing lateral movement of the overlapping rear end portions of said headband with respect to one another, and a spring assembly comprised of a substantially flat plate with a central opening defined therethrough having a geometry adapted to fit over and mate with the pinion of said rotational element, said spring assembly being adapted to engage the ring gear defined by said insert to resist rotation of the rotational element relative to said housing sections.