US 4,229,813 A · Elapsed time indicator

Abstract

A time indicator which is substantially unaffected by variations in temperature. The indicator utilizes a silicone oil which is slowly absorbed onto and moves up a porous strip at a rate which is a function of time. One side of the strip is printed with an oil soluble ink, while the other side is unprinted. The printed side of the strip is laminated with polyethylene film to an unprinted strip. As the silicone oil moves up the strip, the oil contacts the ink causing a dye in the ink to migrate from the printed side to the unprinted side, thus providing a measurable color front moving up the strip. The oil is contained in a frangible ampul and a sponge with a small hole at the bottom is situated between the ampul and the strip. The indicator is substantially unaffected by normal variations in temperature and humidity.

Claims17

Dependent claims

A time indicator device comprising:

a reservoir, said reservoir containing dimethylpolysiloxane;
a porous indicator member, one side of said porous member being impregnated with a dye, said dye being at least slightly dispersible in said dimethylpolysiloxane;
said reservoir and said porous member being in a close relationship with one another;
said dimethylpolysiloxane adapted to escape from said reservoir upon activation of said reservoir wherein said dimethylpolysiloxane will spread onto said porous member, said dimethylpolysiloxane wetting said porous member thus permitting said dye to flow from said one side of said porous member to the other whereby the movement of said dimethylpolysiloxane on said porous member provides an indication of the passage of time, said dimethypolysiloxane being substantially independent of temperature and relative humidity.

1 more element

Dependencies are inferred from the claim text.

Elapsed time indicator

Life of this patent

Elapsed time indicator

Life of this patent

Abstract

Claims17