Supercooled liquid thermal generator and improved triggering device

DETAILED DESCRIPTION OF THE INVENTION Now referring to FIG.
1, a portable heat generating pad generally designated 10 is shown as including an outer flexible plastic cover 11, heat sealed at its edge 12 to provide a flexible pack, in the example given, approximately four inches by four inches by one-half inch in size.
Other sizes of such pads are possible in varying configurations for various uses as an encircling portion of the body to apply localized heat or any of a large variety of other shapes.
For purposes of description of this invention, a simple rectangular pad 10 is sufficient.
A portion of the cover 11 is broken away to show the interior which is a material 13 such as sodium acetate which exhibits the property of being supercooled at room temperature and the property of conversion upon being triggered from a liquid to a polycrystaline state with heat energy given off during crystalization.
The cover 11 is preferably of almost any flexible plastic material such as polyethylene provided it is liquid impermeable and undamaged by heating temperatures in the 220 degree F.
range.
Note that three additional heat seal segments 14 are used to partially segregate one corner of the pad 10 from the rest but allowing free movement of the medium 13 between the corner and the remainder of the pad 10.
In FIG.
1 and better shown in FIG.
2 is a triggering device 15 located in the segregated corner 16.
The triggering device 15 is actually visible through the cover 11, if it is transparent and when the material 13 is in its liquid state.
Whether visible or not, the triggering device 15 may be felt in the corner 16 by placing the thumb and fore finger on top and below the corner 16.
The triggering device 15 is a closely wound (turns in contact) hollow helical spring.
Typical dimensions for a stainless steel spring are 1/8 inch outside diameter, length 1/2 inch, wire size 0.
031 with approximately 32 turns per inch.
The spring needs to have sufficient stiffness to maintain its shape and sufficiently resilient to allow binding by the application of pressure by the fingers through the cover 11