Abstract:
A direct current-to-alternating current inverter employing a silicon controlled rectifier (SCR) is described in which control means is provided to promptly and automatically restore inverter operation after a commutation failure. The control means includes means for sensing the instantaneous voltage across the SCR and comparing this voltage with a threshold voltage. Whenever the SCR voltage is lower than the threshold voltage, the gating pulses to the SCR and a series connected chopper of the inverter are inhibited. When the threshold voltage is exceeded, gating pulses are passed to the SCR and the chopper, thereby providing normal inverter operation.
Abstract:
Solid state induction surface cooking units for domestic electric ranges and other cooking appliances are defined with respect to the operating parameters and functional components of complete induction heating systems suited for this use. The surface cooking units are designed for reliable, convenient, and safe operation, and for circuit packaging using hybrid and monolithic integrated circuits. Wide range power control of the inverter power circuits is needed for general cooking but is obtained within a limited ultrasonic operating range of the power semiconductors. The inter-dependent electrical and magnetic characteristics utilized in solid state induction cooking are related to the achievement of such desirable user features as the cool cooking surface, fast utensil warm-up, responsive heating, and unrestrained utensil mobility. In addition to cooking by changing the relative heating level, cooking is performed by setting the desired utensil temperature and by setting the desired utensil power level.
Abstract:
An economical smooth-top cooking appliance for inductively heating cooking utensils preferably comprises a flat air-core induction heating coil driven at an ultrasonic frequency by a simplified one-thyristor, one-transistor, or two-transistor resonant inverter. The series and parallel resonant circuits in the inverters are formed by a capacitor and the induction heating coil. The one-thyristor series resonant circuit is desirable because power control to adjust the cooking temperature is obtained by the combined effect of increasing the frequency and amplitude of the sinusoidal current pulses supplied to the coil. The coil is also movable to change the gap spacing between coil and utensil to vary the coupled power. Flux beneath the coil is used for warming purposes.
Abstract:
Electronic circuitry for sequentially firing photoflash lamps of an array of multiple flash lamps. The circuitry comprises means for causing capacitors to be charged, at different rates of charging, upon the occurrence of a start-flash signal. These capacitors are respectively associated, by means of solid state switching devices, with certain flashlamps of the array, and the unfired flashlamp associated with the charging capacitor which first reaches a predetermined voltage, will be the first to fire. Alternatively, the first lamp to be fired need not be associated with a capacitor. Upon a lamp firing, disenabling circuitry causes discontinuing of charging of the capacitors until occurrence of the next start-flash signal, whereupon the capacitors repeat or resume their charging until the unfired flashlamp becomes fired which is associated with the next charging capacitor to reach the predetermined firing voltage. The procedure is repeated for causing sequential firing of all flashlamps in the array. Circuit modifications and alternative embodiments disclosed, including a single-capacitor circuit.
Abstract:
A low cost opto-electronic transducer comprises a molded body of material having a pair of depressions therein. A semiconductor light source is located in one of the depressions and a photoresponsive device is located in the other. The molded body may comprise an opaque material, or, alternatively, the surfaces of the depressions may be coated with opaque material. This prevents direct illumination of the photoresponsive device by light emitted by the semiconductor light source. The depressions, and consequently the semiconductor light source and photoresponsive device contained therein, are closely spaced thereby eliminating any requirement for elaborate lens systems for focusing emitted or received light. The resulting product is a simple and inexpensive optical transducer for detecting objects at close ranges.
Abstract:
A coaxial opto-electronic transducer adapted for fabrication by integrated circuit techniques is disclosed. A semiconductor light source is disposed on a base member. A support member having a void therein is disposed about the semiconductor light source on the base member. A polycrystalline photoresponsive device is located on the support member proximately the void therein. Light emitted by the light source is reflected from an object in the path of propagation of the light and a portion of the reflected light is directed onto the photoresponsive device. Since the polycrystalline photoresponsive device is on the order of 1 mil in thickness, and is spaced from the periphery of the void in the support member, the support member serves to prevent direct illumination of the photoresponsive device by light emitted by the semiconductor light source.
Abstract:
Induction surface cooking units are used to supply voltage to specially modified cordless auxiliary kitchen appliances and other small electrical apparatus, either motorized or resistive, placed on the counter-top cooking surface. In similar fashion a universal energizer unit comprises an inductively coupled receptor coil and rectifier with plug-in receptacles for other equipment.
Abstract:
The control circuit for an inverter is suitable for fabrication as an integrated circuit and includes, in addition to turn-on circuitry, protection circuits to assure reliable and automatic operation under abnormal circuit conditions such as overvoltages and low input voltages tending to cause device and power circuit failures. Voltage responsive sensors such as Zener diodes sense the appropriate voltages at selected points on the power circuit and modify the operation of the control circuit, preferably by over-riding and inhibiting the turn-on circuitry. Disclosed with regard to a one-thyristor, variable frequency series resonant inverter with an added maximum frequency control, the protection circuit technique is applicable to inverters generally.
Abstract:
An ultrasonic frequency induction surface cooking unit heats aluminum foil and other thin metal utensils placed on the cool cooking surface. For optimum heating the aluminum foil has a thickness of 0.5 mils. A uniform heating distribution is obtained by preferably using a rectangular induction heating coil with several series-connected elongated coil sections, or by varying the metal thickness to graduate the energy acceptance. Frozen convenience foods can be defrosted in this manner, and the aluminum foil can be wrapped about the food and shaped by the user into disposable utensils using a set of molds. Disposable foil cooking obviates the clean-up and storage problems of pots and pans.
Abstract:
Disclosed herein are various single wall and double-walled inductively heatable vessels for heating, serving and storing food. In general, each vessel is comprised of an inductively heatable inner part, or inner section, and an outer part, or outer section, which is not inductively heatable. For example, immediately after the vessel and food contained therein has been inductively cooked, or heated, on an induction appliance, the vessel may be rested directly on the surface of a conventional dining table without fear of burning the surface of the dining table and without fear that any of the diners will burn themselves by touching the outer part of the vessel. Such fears are abated because only the non-heated outer part of the vessel which is near room temperature touches the dining table and is safely accessible to the diners. The inductively heatable inner part, or section, of the vessel may be comprised of a vapordeposited metallic coating, metallic foil or sheet composite thereof, embedded powdered metal or coiled wires while the nonheated outer part or section may be comprised of suitable thermal insulation material such as plastics, glass, or ceramics, etc.