Induction heating cooking appliance

Details Induction heating cooking appliance Induction heating cooking appliance

1982-09-09

1984-06-26

Envall, Jr., Roy N.

Electric heating

Metal heating

Of cylinders

219 1049R, H05B 504

Patent

active

044568070

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to an induction heating type cooking appliance for heating a metallic pan and cooking food by induction heating and more particularly it relates to an induction heating type cooking appliance wherein keys are provided on an operational section for controlling the operation of the appliance and especially for preventing the appliance from operating except when the keys are actuated in a proper manner.
2. Description of the Prior Art
The induction heating type cooking appliance having a maximum temperature which does not as a rule rise above the temperature of a pan has been well accepted as a fireless cooking appliance which is excellent in its safety and cleanliness. However, since no naked fire nor a heated portion is visible, problems are in fact experienced in that the user may get a burn on touching hot metallic articles (for example, a knife and a fork) carelessly placed thereon. Moreover, because it is preferable that an operational section be flush with the heating surface from the standpoint of operability and resistance to water, induction heating type cooking appliances with membrane switches or touch switches which are manually operable from above are most desirable. Nevertheless, such appliances have the constant danger of a faulty operation when an object happens to fall onto any input key or an animal such as a pet touches the key. A prior art approach to avoiding such problems is that a secret number is so programmed that the operational section is locked or unlocked only when a plurality of the keys are actuated in a predetermined order. Inputting such a secret number whenever the appliance is to be used is troublesome, adds to the complexity of the appliance controller, and tends to detract from the reliability of the appliance itself.


SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an induction heating type cooking appliance having a touch responsive input device wherein a timer function is provided for the input device to thereby turn off the power supply unless any output setting key is actuated within a given period subsequent to the actuation of the input keys and not to turn on power supply unless the keys are actuated in a predetermined order.
Specific embodiments of the present invention will now be described by reference to the accompanying drawings.


BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram of an induction heating type cooking appliance according to a preferred embodiment of the present invention;
FIG. 2 is a circuit diagram of a first timer circuit in the same appliance;
FIG. 3 is a view showing waveforms developing in the progress of operation of the first timer circuit in the appliance;
FIG. 4 is a circuit diagram of principal components of the appliance;
FIG. 5 is a circuit diagram of an induction heating type cooking appliance according to another embodiment of the present invention;
FIG. 6 is a circuit diagram showing details of the embodiment shown in FIG. 5; and
FIG. 7 is a circuit diagram of an induction heating type cooking appliance according to still another embodiment.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a frequency converter 3 is connected via a power switch or a triac 2 to an AC power source 1, which converter 3 includes a rectifier 4 for full-wave rectifying the power source 1, a smoothing capacitor 5 for smoothing the resultant pulsating current, a thyristor 7 connected via a choke coil 6 to the resulting DC supply, a freewheel diode 8 reversely connected in parallel with the thyristor 7, and a commutation capacitor 9 connected in parallel with the thyristor and forming a series resonance circuit together with a heating coil 10 for ensuring commutation in the thyristor 7.
A control circuit 11 will now be described in terms of a touch control circuit. Because of the necessity of operating a logic circuit so as to activate the triac 2 when the triac 2 is in off position but when the control ci

REFERENCES:
patent: 4129767 (1978-12-01), Amagami et al.
patent: 4169222 (1979-09-01), Tucker
patent: 4191188 (1980-03-01), Belt et al.
patent: 4206336 (1980-06-01), Cunningham
patent: 4319109 (1982-03-01), Bowles

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