Warmer for temperature conditioning wet dressings and other articles

• US 4,495,402 A
• Filed: 10/02/1981
• Issued: 01/22/1985
• Est. Priority Date: 10/02/1981
• Status: Expired due to Fees

• Current Assignee: Alba-Waldensian, Inc. (Litef Holdings, Inc.)
• Original Assignee: W A Whitney Company
• Inventors: Burdick, Thomas H., Vasconcellos, Alfred, Whitney, William G.
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): Evans, Geoffrey S.
• Application Number:
  US06/307,954
• Time in Patent Office: 1,208 Days
• Field of Search: 219/385, 219/386, 219/387, 219/214, 219/391, 219/412-414, 219/527, 219/481, 219/482, 219/510, 219/516, 219/506, 219/497, 219/521, 604/289, 604/291, 604/304, 221/150 A, 221/150 HC, 221/150 R, 221/146, 221/56
• US Class Current: 219/214
• CPC Class Codes: A47J 27/004 with integral electrical heating means drinking cups with integral heating means A47J36/2466
• CPC Class Codes: A61F 7/0241 Apparatus for the preparation of hot packs, hot compresses, cooling pads, e.g. heaters or refrigerators
• CPC Class Codes: H05B 3/00 Ohmic-resistance heating

Abstract

A warmer for heating wet dressings and other articles disposed in a combined heating and storage compartment in stacked relation insures that a bottommost article about to be dispensed is at a proper temperature so as to avoid burning the patient to whom the article is applied. The articles in stacked relation rest on a thin aluminum plate to which an electrical heater is connected for supplying thermal energy thereto, the plate having a center aperture forming a thermal island in which a first thermal sensor is disposed which projects into the compartment in contact with the bottommost one of the articles therein. A circuit board has control circuitry for the heater thereon and is disposed beneath the plate so as to simultaneously function as a stiffener for the plate. The control circuitry is connected to the first sensor as well as to a second thermal sensor which is directly responsive to the temperature of the heater. The control circuitry automatically limits the thermal energy supplied to the compartment as a function of the sensed temperature of the first and second thermal sensors for bringing the temperature of the bottommost article to a selected level and maintaining the temperature of that article at the selected level.

Claims

1. A warmer for articles disposed in stacked relation comprising,

a container made of thermal and electrical insulating material and forming an inner compartment,

a thin aluminum plate in the range of from about 0.013 to 0.016 inches in thickness disposed horizontally in said inner compartment to partition the compartment into an upper combined storage and heating compartment for receiving said articles in stacked relation to be warmed, and a lower mechanism compartment,

electrical heating means on the lower side of said thin aluminum plate to deliver thermal energy thereto,

said thin aluminum plate having a center aperture forming a thermal island in which is disposed in thermal isolation a first sensing means projecting into said combined heating and storage compartment for engaging a bottommost one of said articles in stacked relation in said combined heating and storage compartment for sensing the temperature of said bottommost article,

and circuit control means connected to said heating means including said first sensing means and further including a second sensing means directly responsive to the temperature of such said heating means, and including means for selectively limiting the thermal input delivered to the storage compartment as a function of the sensed temperature of said first and second sensing means for bringing the temperature of said bottommost article to a selected level and maintaining said temperature of said bottommost article at said selected level.

2. An electrical warming device comprising:

an insulated combined storage and heating container;

a thin metallic plate positioned within said insulated storage and heating container and capable of supporting at least two elements to be warmed, said elements being placed in a stacked arrangement on said thin metallic plate;

a means for dispensing a bottom one of said elements adjacent to said thin metallic plate;

a first thermal sensor mounted to said thin metallic plate for contact with said bottom one of said elements, said first thermal sensor being thermally isolated from said thin metallic plate for monitoring the temperature of said bottom element placed on said thin metallic plate;

a second thermal sensor mounted to said thin metallic plate and positioned for directly monitoring the temperature of said thin metallic plate;

heating means for increasing the temperature of said thin metallic plate for increasing the temperature of said bottom element to a predetermined level;

control means connected to said heating means and to said first and second thermal sensors and being responsive to signals received from said first and second thermal sensors for automatically reducing and maintaining the temperature of said thin metallic plate upon the temperature of said bottom element reaching a selected temperature, such that said thin metallic plate and said bottom element are maintained at a substantially constant temperature, and for automatically disengaging said heating means when a selected maximum temperature for said thin metallic plate is exceeded.

3. An electrical warming device comprising:

an insulated container;

a non-self-supporting metallic plate positioned within said insulated container for supporting at least two elements to be warmed in a stacked arrangement on said metallic plate;

heating means positioned beneath said metallic plate for converting electric current into heat for warming said metallic plate;

a means for dispensing a bottom one of said elements in said stacked arrangement adjacent to said plate;

a circuit board structurally connected beneath said metallic plate for stiffening said metallic plate;

a first thermal sensor mounted to said metallic plate in thermal isolation therefrom in contact with said bottom element for monitoring the temperature of said bottom element on said metallic plate;

a second thermal sensor mounted to said metallic plate for directly monitoring the temperature of said metallic plate;

control means carried on said circuit board connected to said first and second thermal sensors and to said heating means for automatically reducing and maintaining the temperature of said metallic plate upon the temperature of said bottom element reaching a selected temperature in response to a signal from said first sensor, such that said metallic plate and said bottom element are maintained at a substantially constant temperature and for automatically disengaging said heating means when a selected maximum temperature for said metallic plate is exceeded in response to a signal from said second sensor.

4. The electrical warming device of claim 3 in which said insulating container consists of acrylonitrile, butadiene, styrene for both thermal and electrical insulation.

5. The electrical warming device of claim 3 in which said metal plate has a thickness in the range of 0.013 to 0.016 inches.

6. The electrical warming device of claim 3 in which said control means includes a thermal fuse for automatically disengaging said heating means.

7. The electrical warming device of claim 3 in which said circuit board is mounted vertically and diagonally to the underside of said metallic plate.

8. The electrical warming device of claim 3 in which said heating means is an electric heating pad positioned below and abutting said metal plate.

9. The electrical warming device of claim 3 in which said first thermal sensor is positioned within a thermal island formed on said metal plate for insuring accurate temperature measurements of said bottom element.

10. The electrical warming device of claim 3 in which said elements are wet dressing packs.

11. In a wet dressing warmer having a metal plate, an apparatus for controlling the temperature of said metal plate and a wet dressing pack laid directly on top of said metal plate, said apparatus comprising:

an electric heating pad connected to a power source, said heating pad affixed to the underside of said metal plate;

a first thermal sensor mounted to and protruding from said metal plate and thermally isolated therefrom for direct contact with said wet dressing pack;

a second thermal sensor mounted to and directly abutting said metal plate for measuring the temperature of said metal plate;

control means connected to said heating pad and responsive to said first and second thermal sensors for increasing the temperature of said metal plate for increasing the temperature of said wet dressing pack to a selected level; and

control means connected to said heating pad and responsive to said first and second thermal sensors for reducing and maintaining the temperature of said metal plate for maintaining the temperatures of said metal plate and said wet dressing packs at a same selected level.

12. The apparatus of claim 11 further comprising a rectifier bridge for supplying full wave rectified AC voltage from said power source to said heating pad.

13. The apparatus of claim 11 which said control means for increasing the temperature of said metal plate comprises:

a first comparator having a first input connected to said first thermal sensor and a second input connected to a reference voltage through a first potentiometer for setting a threshold voltage for said first comparator;

a second comparator having a first input connected to said second thermal sensor and a second input connected to said reference voltage through a second potentiometer for setting a threshold voltage for said second comparator;

a transistor interconnected between said heating pad and said power source having a base electrode connected to the output of said first and second comparators, said comparators supplying a signal to said base electrode for permitting said transistor to supply power from said power source to said heating pad when the threshold voltages for said first comparator and for said second comparator are simultaneously exceeded.

14. The apparatus of claim 11 in which said control means for maintaining said metal plate at a minimum temperature and said means for reducing and maintaining the temperature of said metal plate comprise:

a comparator having a first input connected to said second thermal sensor and a second input connected to a reference voltage through a potentiometer for setting a threshold voltage for said comparator; and

a transistor interconnected between said power source and said heating pad having a base electrode connected to an output of said comparator, said comparator supplying a signal to said base electrode for permitting said transistor to supply power from said power source to said heating pad until said threshold voltage is exceeded.