초록 ▼

A time temperature indicator in the physical form of a substantially planar label-like member that can be placed on perishable products to give a visual indication of deterioration or spoilage of the product due to its exposure to temperature. The indicator includes a galvanic cell which serves both

A time temperature indicator in the physical form of a substantially planar label-like member that can be placed on perishable products to give a visual indication of deterioration or spoilage of the product due to its exposure to temperature. The indicator includes a galvanic cell which serves both as power source and, by virtue of a partly consumable electrode, as an indicating coulometer, indicating charge transfer wherein the charge transferred is an electrical analog of the time integral of the deterioration rate of the product as a function of temperature; the analog of the deterioration rate is the current drawn from the cell when a device having a current drain which is an approximate exponential function of temperature is connected to the terminals of the cell. The visual indication is provided by the contrast of the prearranged pattern of a protected part of the consumable electrode against the electrolyte which becomes visible when the unprotected part of the electrode is consumed.

대표청구항 ▼

An apparatus for indicating the deterioration of a packaged perishable product that deteriorates at a rate approximately exponentially related to the temperature of the product, the apparatus being adapted to be attached to the package in which said product is contained and comprising: (a) a substan

An apparatus for indicating the deterioration of a packaged perishable product that deteriorates at a rate approximately exponentially related to the temperature of the product, the apparatus being adapted to be attached to the package in which said product is contained and comprising: (a) a substantially planar, label-like, galvanic cell having a consumable electrode, an electrolyte, and a patterned mask positioned between said electrode and the electrolyte and protecting a predetermined portion of said electrode against galvanic erosion to provide a predetermined visual indication when the time integral of the instantaneous currents passed through said cell amounts to a predetermined coulombic total, and (b) circuit means including a semiconductor device having a temperature dependent current characteristic connected to said cell for controlling the through-put current in a manner such that the instantaneous current amplitude at any given time is a direct and substantially exponential function of the temperature at such time, with said function substantially corresponding to the time rate of deterioration as a function of temperature characteristic of the perishable product to which the apparatus is to be attached, whereby said through-part current consumes that portion of the consumable electrode not protected by said patterned mask, exposing the electrolyte to view through said electrode and providing a visual indication corresponding to the pattern of said mask.