Self-contained warming pad

DETAILED DESCRIPTION The present invention overcomes each of the aforementioned problems or shortcomings by providing a self-contained warming pad which is light in weight, small in size, conveniently activated, safe during use and capable of producing sustained surface temperatures and delivering substantial amounts of beneficial heat for topical use.
The warming pad disclosed in the present invention includes a heating element, preferably an electrochemical heating element, a dose of activating liquid beside the element and within a frangible container, and a substantially liquid-impervious cover for the element and container which defines at least one tortuous air passage therethrough to allow proper activation and sustained production of heat while at the same time preventing liquid in the pad from exiting the pad.
The cover for the heating element and container of activating liquid preferably includes a layer of thermal insulation.
Such a cover would not only prevent permeation by the liquids inside but would serve to protect the skin of a user from the intense heat of the heating element.
The tortuous air passage through the cover is preferably in the form of a peripheral annular breathing passage about the edge of the pad.
Such passage may be formed by two sheets of heat sealable material which form the cover.
The sheets are sealed together by inner and outer annular peripheral seals, the inner seal extending about the element and the container to form a central enclosure for them, and the outer seal extending about and spaced from the inner seal to form a peripheral air passage between the seals.
Two peripherally spaced openings in the peripheral air passage complete a preferred tortuous air passage through the cover.
One of the openings is defined by the inner seal to allow fluid communication between the central enclosure and the peripheral passage, and the other opening is defined by the cover to allow fluid communication between the atmosphere and the peripheral passage.
A porous resilient mass may be placed within the pad to provide a breathing capacity