FOOD WARMING DISH

• US 3,739,148 A
• Filed: 01/28/1972
• Issued: 06/12/1973
• Est. Priority Date: 01/28/1972
• Status: Expired due to Term

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: William D. Ryckman Jr
• Inventors: Ryckman, William D. Jr.
• Primary Examiner(s): Mayewsky, Volodymyr Y.
• Application Number:
  US05/221,532
• Time in Patent Office: 501 Days
• Field of Search: 219/441,465,501,508,521 99/422
• US Class Current: 219/441
• CPC Class Codes: A47J 39/02 Dish-warmers; Devices to keep food hot
• CPC Class Codes: G05D 23/2754 using bimetallic element

Abstract

A food warming dish that employs an electrical resistance heating element for heating a heat retentive material inside the dish. Energization of the heating element is regulated by a semiconductor control device having two terminals in electrical circuit with the heating element and a control gate that permits electrical current to flow between the two terminals only after a signal has been applied to the control gate. The semiconductor control device is arranged in an electrical circuit such that a temperature responsive switch in series relationship between the heating element and semiconductor control device prevents a signal from being sent to the control gate when the temperature reaches a set predetermind temperature.

Claims

1. An electrically heated apparatus comprising:

a. a hollow food receiving dish structure containing a heat retentive material therein, b. a pair of terminals, c. an electrical resistance heating element being disposed within the heat retentive material, d. a semiconductor control device connected in series with said heating element across said terminals for controlling the flow of electric current therethrough, said control device having a control gate for receiving control signals for turning-on said control device, e. a resistive circuit connected in series with said heating element across said terminals, the resistance of said resistive circuit being sufficiently greater than the resistance of said heating elements to substantially prevent the flow of current through said heating element when said control device is not conducting and normal operating voltage is applied to said terminals, and d. control signal transmission means interconnecting said control gate and said resistive circuit at a point at which the maximum voltage is substantially less than the maximum voltage applied across said terminals, said control signal transmission means including a temperature responsive switch responsive to a set predetermined elevated temperature to move normally closed contacts to an open position to prevent the transmission of a control signal to said control gate.

2. An electrically heated apparatus as defined by claim 1 in which said control signal transmission means further includes reactive means responsive to an alternating voltage applied across said terminals to generate control signals of sufficient magnitude to turn-on said control device at an earlier point in the voltage wave form than would otherwise be possible.

3. An electrically heated apparatus as defined by claim 2 in which said reactive element is a capacitor in series with said temperature responsive switch.

4. An electrically heated apparatus as defined by claim 3 wherein said switch includes a bimetal blade that bends in response to the set predetermined elevated temperature to move the contacts to their open position.

5. An electrically heated apparatus as defined by claim 3 further comprising a thermal fuse connected in series relationship with the heating element to open the circuit of the heating element in the event that the temperature of the heat retentive material reaches a temperature higher than the set predetermined elevated temperature of the temperature responsive switch.

6. An electrically heated apparatus as defined by claim 3 wherein a power connector is adapted for removable engagement with said terminals to supply electrical power to the heating element from a power source.