Portable light-emitting devices that can be worn by the user have been in existence for decades. Although there are many configurations for a user-worn lamp, the fundamental design is the same. These devices consist of an electrical illuminating element, a battery pack (either rechargeable or primary), a housing, and a method for attaching the device to the user's body.
These devices are used in a wide variety of situations that benefit from hands-free operation including but not limited to: mining, cave exploration, subterranean excavation, construction, hiking, climbing, and mountaineering. Users of these devices often put them to use in remote or dangerous situations where an insufficient light source could represent a very serious safety hazard.
One of the main disadvantages of traditional user-worn lamps is that the light projected by the device quickly becomes inadequate for their intended purposes as the battery voltage decays. Because of this problem, users often carry spare batteries that can easily double the effective weight and volume of the device. Many users of these devices are highly concerned about the size and weight of their equipment and find the necessity of backup batteries to be a hindrance. The use of backup batteries also presents an ecological and economic burden.
There have been several attempts at solving the problem of battery voltage decay in such devices through the addition of a user-operated electric generator. These proposed solutions have consisted of either strapping a hand-crank powered electric generator to a standard user-worn lamp or adding a strap to a dynamo-powered flashlight. By adding more components to an existing design these concepts result in a bulky device that add more size and weight than carrying a spare set of batteries.
As with most hand-powered flashlights, attempts at adding an electric generator to a user-worn lamp have made use of a hand-crank with a telescoping handle. In order to keep the size of this device to a minimum the crank must be kept small. This results in a small lever-arm that prohibits users from making use of their full range of motion and leads to inefficient transfer of human energy to the electric-generator.
What is therefore needed is a more compact source of hands-free light that does not require backup-batteries and is efficient to operate.