Food serving tray

• US 4,068,115 A
• Filed: 07/17/1975
• Issued: 01/10/1978
• Est. Priority Date: 05/09/1974
• Status: Expired due to Term

• Current Assignee: Sweethart Cup Company Incorporated
• Original Assignee: Sweetheart Plastics Incorporated
• Inventors: Mack, Anthony C., Shumrak, George K.
• Primary Examiner(s): Mayewsky, Volodymyr Y.
• Application Number:
  US05/596,969
• Time in Patent Office: 908 Days
• Field of Search: 219/201, 219/385, 219/386, 219/387, 219/439, 219/462, 219/521, 219/530, 219/533, 219/540, 126/246, 126/375, 165/2, 165/48, 165/185, 312/214, 312/236, 312/330, 99/447
• US Class Current: 219/386
• CPC Class Codes: A47B 2031/026 having warm and cold compartments
• CPC Class Codes: A47B 31/02 with heating, cooling or ventilating means
• CPC Class Codes: A47J 39/006 for either storing and preparing or for preparing food on serving trays, e.g. heating, thawing, preserving

Abstract

A food serving system for delivering prepared meals to locations remote from the point of preparation, such as to patients in hospitals and nursing homes, which includes a mobile cart having its own low voltage rechargeable power pack that may be utilized to make the cart self powered. The cart has a tier of racks for carrying removable, generally flat, individual, food serving trays. The trays may be disposable or reusable. Each tray is provided with one or more thermally isolated heat transfer devices which may be energized when the tray is placed on a rack in the cart. The trays are constructed to carry conventionally styled, removable dishes, bowls, cups, etc., that may be either disposable or reusable, and the dishes and bowls containing foods to be maintained at a reduced or elevated temperature are placed on the heat transfer devices. The heat transfer devices are intended to maintain the food in the dishes and bowls at the desired serving temperature for extended periods without affecting the temperature of the foods and beverages in other dishes, bowls and cups on the trays, so that when the cart is moved about the hospital they remain at their desired temperatures and the individual trays may be brought to the patients with the different foods and beverages at their separate selected temperatures.

Claims

1. A food serving tray comprising

a horizontal support comprising a thermally and electrically insulating material and an upturned edge portion,

an opening in the support generally corresponding in size to the bottom surface of a food container,

a circuit assembly base secured to the bottom of the support and aligned with the opening,

a disc on the tray made of good heat conductive material and generally conforming in shape to the opening and aligned with the opening, said disc and base forming a closed cavity in the tray with the disc forming a portion of a top surface of said tray and being secured to the tray,

an electric heating element secured to the tray in the cavity and in contact with the bottom surface of the heat conductive disc and with its bottom spaced from the base and lying in the cavity,

and electrical contacts in the tray and electrically connected to the electric heating element by conductors in the cavity for carrying energy to the electric heating element to energize it.

2. A tray as defined in claim 1 further characterized by

said electrical heating element being a positive temperature coefficient heater.

3. A tray as described in claim 2 further characterized by

a rib in the upper surface of the tray adjacent the edge of the opening for defining the periphery of the heated area of the tray and for retaining a food container on the support in contact with the disc.

4. A tray as descrbied in claim 3 further characterized by

said disc being made of aluminum.

5. A tray as described in claim 2 further characterized by

said base and disc sealing the electrical heating element in the tray so that it may be immersed in water for washing.

6. A food serving tray comprising

a support comprising thermally and electrically insulating material,

means defining a localized area in the surface of the support made of a good heat conductive material and fixed in position on said support,

portions of the support surrounding the localized area inhibiting the lateral transfer of heat from the localized area to other portions of the support,

an electrical heating element secured to the tray located in a cavity defined by said support and in heat transfer contact with the means defining the localized area while being insulated from said suppport,

and electrical contacts in the tray and electrically connected to the electric heating element for energizing said electric heating element,

said electric heating element being sealed in said tray so that it may be immersed in water for washing.

7. A tray as defined in claim 6 and further comprising,

means contacting the localized area for retaining food in heat exchange relationship with said area.

8. A tray as defined in claim 7 further characterized by

said means contacting the localized area being rims for containing a food dish separate from the tray.

9. A food serving tray in accordance with claim 6 further characterized by

said electric heating element being capable of heating foods held on the tray at a temperature in the range of from 130°

to 170°

F.

10. A food serving tray in accordance with claim 6 further characterized by

said electric heating element being capable of heating foods held on the tray at a temperature in the range of from 140°

to 160°

F.

11. An immersible serving and food temperature controlling tray structure comprising:

a tray body of thermally and electrically insulating material having a top layer for receiving food containers and a bottom layer;

at least one heat exchange surface portion of thermally conductive material integrally set and sealed in said top layer;

peripheral boss means surrounding said heat exchange surface portion for conformally receiving and indexing a food container over said heat exchange surface portion and substantially preventing lateral movement of said container on said top layer;

a sealed cavity defined in said tray between said top and bottom layers thereof;

an electric heating element secured to the tray in said cavity juxtaposed with the underside of said heat exchange surface portion and spaced from said bottom layer to minimize the transfer of heat through said bottom layer;

exposed contact means sealed in said tray for connection to a source of electric power; and

connector means extending from said contact means through said tray between said top and bottom layers and into said sealed cavity to said electric heating element.

12. The invention defined in claim 11, wherein:

said tray body is comprised of plastic material; and

said heat exchange surface portion comprises a metallic sheet.

13. The invention defined in claim 11, wherein said peripheral boss means comprises an upstanding continuous ridge of thermal insulating material integral with said top layer and defining a receiving socket for a conformally shaped food container.

14. The invention defined in claim 11, wherein said electric heating element comprises heater means for maintaining a predetermined temperature in a food container placed on said heat exchange surface.

15. The invention defined in claim 14, wherein said heating element is a positive temperature coefficient electric heating element.

16. A food serving tray for a plurality of food products in a like plurality of containers mounted on said tray, comprising:

heat exchange surface portions on said tray for conformally receiving selected ones of said containers;

electric heating elements secured to the tray with at least one element substantially contacting the bottom surface of each heat exchange surface portion for maintaining predetermined temperatures within said containers on said surface portions;

said heat exchange surface portions being thermally and electrically isolated from the remainder of said tray means; and

means integral with said tray means for connecting said electrical heating elements with a source of power external to said tray means to energize said electrical heating elements,

said heat exchange elements being sealed in said tray means so that said tray means can be washed in water.

17. The food serving tray as defined in claim 16, wherein said electric heating elements and said surface portions form heater means for maintaining respectively predetermined temperatures in respectively selected ones of said food containers.

18. The food serving tray defined in claim 17, wherein said electric heating elements comprise positive temperature coefficient electric heaters.