×

Time-temperature indicator

  • US 4,057,029 A
  • Filed: 03/08/1976
  • Issued: 11/08/1977
  • Est. Priority Date: 03/08/1976
  • Status: Expired due to Term
First Claim
Patent Images

1. A time-temperature indicating device comprising:

  • a diffusion layer of a material having a first impermeable, crystalline-like state and a second permeable, liquid-crystalline state, said material being capable of transition between said first and said second states at a clearly defined temperature;

    an indicator disposed on one side of said diffusion layer; and

    a reactant material for said indicator normally maintained out of contact with said indicator by said diffusion layer, said reactant material having a predetermined rate of diffusion through said diffusion layer to contact and react with said indicator when said diffusion layer is in the permeable, liquid-crystalline state.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×