Patent US3739148A successfully refreshed from Google Patents.
US3739148A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Food warming dish
Assignee: General Electric Co
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Filing: 1972-01-28
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Granted: 1973-06-12
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Expires: 1992-01-28
Abstract
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.
Inventors
- 👤 W Ryckman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:42
CPC Classifications
A; A47; A47J; A47J39/00; A47J39/02; G; G05; G05D; G05D23/00; G05D23/19; G05D23/275; G05D23/27535; G05D23/2754
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
203 words
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.
Claim 2
Dependent Claim
203 words
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.
Claim 3
Dependent Claim
55 words
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.
Claim 4
Dependent Claim
24 words
An electrically heated apparatus as defined by claim 2 in which said reactive element is a capacitor in series with said temperature responsive switch.
Claim 5
Dependent Claim
34 words
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.
Claim 6
Dependent Claim
56 words
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.
Claim 7
Dependent Claim
33 words
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.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |