Miniature flashlight

DETAILED DESCRIPTION The present invention is directed to a flashlight having improved characteristics.
A high quality flashlight having a closed internal volume includes a one-way valve associated with a passage extending to atmosphere from the closed internal volume.
Such an arrangement provides for the release of internal pressures within the flashlight and yet does not accommodate flow into the flashlight when the internal volume is closed.
In this way, substantial overpressure is accommodated without breaching the integrity of the unit.
With vacuum being limited in magnitude by its very nature, no provision is made for the release of such vacuum.
In this way, introduction of harmful elements is avoided.
Membrane mechanisms not capable of resisting substantial overpressure are also avoided.
In another aspect of the present invention, a circumferential resilient one-way valve is contemplated which defines an extended valving area.
Blockage through the valve is avoided in this way.
Multiple passages through threads and splines between flashlight components also can contribute to an avoidance of such problems.
In a further aspect of the present invention, the flashlight may include variable focus through movement of the flashlight head toward and away from the flashlight barrel.
The range of internal pressures can be maintained within limits ranging from a theoretical absolute vacuum to a maximum of ambient pressure experienced during assembly of the unit.
In more detailed aspects of the present invention, improved optical characteristics, including variable light dispersion as well as an ambient unfocused light source, are contemplated.
An electrical switching function as well as variable focus through relative movement of the head and the barrel may also be provided.
These features may also be achieved in a miniature hand-held flashlight of high quality construction.
Thus, it is an object of the present invention to provide an improved flashlight.
Other and further objects and advantages will appear hereinafter