Microwaveable container having temperature indicating means

• US 4,933,525 A
• Filed: 03/22/1989
• Issued: 06/12/1990
• Est. Priority Date: 03/22/1989
• Status: Expired due to Term

• Current Assignee: Tenneco Plastics Company
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: St. Phillips, Eric A.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US07/327,654
• Time in Patent Office: 447 Days
• Field of Search: 219/10.55 E, 219/10.55 B, 219/10.55 F, 219/10.55 R, 219/506, 426/88, 426/107, 426/241, 426/243, 374/159, 374/160, 374/161, 374/162, 374/149, 374/141, 116/216, 116/219, 99/DIG. 14
• US Class Current: 219/725
• CPC Class Codes: A47J 36/027 Cooking- or baking-vessels specially adapted for use in microwave ovens; Accessories therefor
• CPC Class Codes: G01K 11/16 of organic materials
• CPC Class Codes: G01N 31/229 for investigating time/temperature history

Abstract

A reusable microwaveable container having a temperature indicator mounted permanently to the side walls of the container. The temperature indicator is a liquid crystal film display device having a plurality of display devices which indicate various temperature levels. The liquid crystal films change color in response to a preset temperature such that each display changes color at incrementally increasing temperatures. The displays are reversible in that they return to their original color as the temperature decreases. Alternately, or additionally, the temperature sensing indicator may be provided on a closure lid which fits over the container, so that the temperature may be detected from steam rising from the food being cooked or heated.

Claims

1. A container for the cooking or heating of foods, said container being constructed of microwave-transparent material and having a bottom and wall structure integrally connected with and extending upwardly from said bottom;

and temperature-indicating means on said side wall structure comprising at least one temperature-sensitive liquid crystal film indicator, said indicator having a predetermined temperature sensitivity such that said film undergoes a visible color change at a change from a predetermined initial temperature, each said film indicator consisting of a strip fastened to an exterior surface of the wall structure of said container and having an array of said indicators thereon, said indicator being imparted a visible color change at different incrementally increasing temperatures, said color change being reversible so as to revert said indicator to its original color at said predetermined initial temperature.

2. A container as claimed in claim 1, wherein said film indicator comprises an adhesive-backed strip which is adhesively secured to said side wall structure for visible external indication of a change in temperature within the container or container contents.

3. A container as claimed in claim 1, wherein said temperature indicating means is embedded in said side wall structure so as to be integrally fastened to said container.

4. A container as claimed in claim 1, wherein said side wall structure is provided with a plurality of said temperature indicating means arranged at various locations about said side wall facilitating visual indication of temperature change from the outside irrespective of the orientation of said container within an oven.

5. A container as claimed in claim 1, wherein said temperature indicating means is mounted on a substrate having a contrasting color to enhance the viewing of a color change.

6. A container as claimed in claim 5, wherein said contrasting substrate backing comprises said side wall structure.

7. A container as claimed in claim 1, wherein said indicators each have an identical original color, said indicators each changing to a different color to indicate a different temperature level.

8. A container as claimed in claim 1, wherein said indicators each change colors at 10°

C. temperature change increments.

9. A container as claimed in claim 1, wherein said indicators each change color in 5°

C. temperature change increments.

10. A container as claimed in claim 1, wherein said container includes with a removable closure lid.

11. A container for cooking or heating of foods, said container being constructed of microwave-transparent material, and having a bottom and an upright side wall structure integrally connected with and extending upwardly from said bottom, and a removable closure lid;

at least one temperature indicating means on said closure lid comprising a strip having at least one temperature-sensitive liquid crystal film indicator thereon, said indicator being imparted a visible color change at different incrementally increasing temperatures, and said color change being reversible to change said indicator back to an original color in response to a decrease in the temperature.

12. A container as claimed in claim 11, wherein said temperature indicating means comprises an adhesive backed strip for securing said indicating means to said closure lid.

13. A container as claimed in claim 11, wherein said temperature indicating means is embedded in said closure lid to form a permanent component of said lid.

14. A container as claimed in claim 11, comprising an array of said indicators on said strip, said indicators each being imparted a visible color change which is reversible to change said indicators back to an original color as the temperature decreases.

15. A container as claimed in claim 11, wherein said temperature indicating means is mounted on a substrate of a contrasting color to enhance the visibility in the color of said indicator to a user.

16. A container as claimed in claim 15, wherein the surface of said closure lid provides a contrasting background.