Temperature indicator

• US 4,156,365 A
• Filed: 05/15/1978
• Issued: 05/29/1979
• Est. Priority Date: 08/02/1976
• Status: Expired due to Term

• Current Assignee: Ferdinand Heinmets, Julian T. Heinmets
• Original Assignee: Ferdinand Heinmets, Julian T. Heinmets
• Inventors: Heinmets, Ferdinand, Heinmets, Julian T.
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US05/905,730
• Time in Patent Office: 379 Days
• Field of Search: 73/343 R, 73/343 B, 73/356, 73/358, 116/114 V
• US Class Current: 374/162
• CPC Class Codes: A47G 19/2227 with means for amusing or giving information to the user A47G23/16 takes precedence
• CPC Class Codes: A47G 2019/225 vessels with thermometers
• CPC Class Codes: G01F 23/22 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water involving the use of floats G01F23/30
• CPC Class Codes: G01K 11/12 using changes in colour, translucency or reflectance

Abstract

Food temperature vessel or other utensil comprising a thermochromic layer at a surface thereof indicating temperature of the food content of the vessel within a safe range above 60° and below 70° C. corresponding to achievement of safety conditions by raising the food content above the minimum temperature of the range to produce reversible protein denaturation in certain microorganisms to limit sporulation, and below a limit corresponding to irreversible protein denaturation and tissue injury of the tongue, lips or throat tissues of the user on the upper end of the range. The thermochromic layer goes through a transition from red to black across the range.

Claims

1. Safe food temperature sensing utensil comprising,

means defining a nonmetallic, food holding vessel,

means defining a thermochromic paint layer on the vessel positioned to be visible to a user and constructed and selected to change color twice in a selected temperature range comprising 60°

-70°

C. to provide indications of the levels of temperature at which denaturation of the food, microbial, growth in the food and tissue injury to the consumer of food carried by the untensil would be likely and to reverse said color changes when recooled.

2. Safe food temperature sensing utensil in accordance with claim 1 wherein the thermochromic paint layer is a thin coating on an outer surface of the utensil.

3. Safe food temperature sensing utensil in accordance with claim 1 wherein the thermochromic paint layer has a definite design form which is set against a different background design form and is distinctly visible thereagainst when below a preselected temperature level and blends therein at or above said level.

4. Safe food temperature sensing utensil in accordance with claim 1 wherein said means defining a thermochromic layer comprises a series of dots of thermochromic material and further comprising,

a corresponding series of dots of different reference colors in juxtaposition with said series of dots of thermochromic material to enable a user to identify the temperature of the utensil by noting correspondence in color between a dot of thermochromic material and a dot of reference color,

and indicia indiating the temperature represented by each reference color beside a respective reference dot.