Abstract: A dental mirror warmer to prevent fogging when the mirror is placed in a patient's mouth includes a housing with a cover having an opening. Below the opening is a heating well to receive the reflective end of the mirror. The well has a stainless steel wall connected to a transformer which supplies high current at low voltage to heat the wall. The supply to the transformer is controlled by a photoresponsive device responsive to insertion of the mirror and a timing circuit which permits current supply for a short heating interval. A temperature sensor shortens the interval when heating cycles are initiated frequently. The photoresponsive device is mounted in the housing in juxtaposition with a light transmissive opening in a wall of the heating well. The photoresponsive device includes a source of light arranged to direct light into the heating well through the opening and a photoresponsive element arranged to receive light reflected from the reflective surface of a mirror inserted into the heating well.

Abstract: A temperature control system for electric surface heater of piled layers of a heating element across which a commercial AC source current is fed and a thermosensitive electrode opposing the element through thermosensitive element showing negative impedance characteristics with temperature rise. In the system, an AC signal voltage different from the source current is applied between the heating element and the thermosensitive electrode, and excessive variations in the signal voltage responsive to the negative impedance of the thermosensitive element is detected to disconnect or connect the heating element and the source.

Abstract: Disclosed herein is a method and a digital electronic steam humidifier control for use with a humidifier system including an electrode boiler to provide a normally repetitive fill, boil, fill-on-drain cycle. The humidifier control includes circuitry for providing an analog signal proportional to the electrode current, and a comparator network which receives the analog signal and a reference voltage and scaled voltages provided by additional circuitry to establish predetermined levels of electrode current at which the control responds.

Abstract: A temperature control system for a resistance element which is heated by a power supply connected to it by a switching member, the switching member being controlled by an electronic circuit which is operative to produce alternate ON-cycles and OFF-cycles whose durations are controlled by separate time constants. The durations of these alternate cycles respectively set the higher and lower temperature limits within which the heating element temperature remains. The electronic circuitry further provides a single initial ON-cycle of greater duration which occurs only when the circuit is newly turned ON and operates to bring the resistance element up to operating temperature from ambient temperature, an indicator being provided to glow during each ON-cycle interval. The control system is illustrated for use with a soldering iron which is supportable in a cradle connected with a switch to turn OFF the system when the iron rests in the cradle.

Abstract: An electrical heater device for heating a clinical mirror. The device comprises a housing having a top, bottom and side walls to define a hollow enclosure. Two spiral coiled electric heating elements are secured in the housing with their heat radiating surface spaced apart and facing each other in juxtaposition to provide concentrated heat in a mirror locating space therebetween. An opening is provided in the top wall in alignment with the mirror locating space through which the mirror can be inserted into the mirror locating space. A switch is positioned in alignment with the mirror locating space below the heating elements. The switch has an activating contact on an upper face thereof located in alignment with the opening in the top wall and the mirror locating space for activation by a clinical mirrow when the mirror element of such is inserted into the mirror locating space.

Abstract: An electric heating element for the top panel of a cooking stove, having terminals adapted to be plugged into a terminal block carried by the stove panel, and embodying means for automatically interrupting current flow to the heating element when a cooking utensil is removed therefrom. The means for automatically interrupting the current flow comprises a weight responsive switch with at least one contact in the terminal block.

Abstract: A presser member, into which the container is loaded, is manually depressable against the action of its return spring into pressure-contact engagement of the container with an electric heating plate containing a PTC heating resistor. The depression stroke produces closure of a switch to energize both the PTC resistor and an electromagnet keeping the presser member in its depressed condition. A timer circuit opens the switch at the elapse of a prealably experimentally determined heating time during which the liquid reaches its consumption temperature, whereby heating is terminated and the return spring lifts the pressure member with the container to unloading position.

Abstract: A device for heating a drink in a thermoplastics container sealed by a metal cover, in which the container is placed in a support upside-down and depressed to bring its cover into contact with an electrical heater, the depression of the container support operating a microswitch which energizes the heater and a support-retaining electromagnet to heat the container for a timed interval. The resistance of the heater is measured during heating by a Wheatstone bridge and utilized to regulate the temperature reached by the heater.

Abstract: A heating unit for heating the contents of a container includes an electrical circuit having a pressure responsive switch that is normally open and a thermally responsive switch that is normally closed, the pressure switch is responsive to a predetermined weight of the container on a pivotally mounted heating element for activating the switch to the closed position for activating the heating circuit. The thermal switch is responsive to an overheating of the unit to interrupt the circuit. The heating unit is provided with a heating element having a conical center portion surrounded by an annular flat or planar surface, for receiving containers having only a predetermined shaped bottom for accommodating the particular shape of the heating element.

Abstract: An apparatus for the storage and preparation of food, especially meals which are to be dispensed, comprising a closable cabinet, at least one tray or shelf which is insertable into such cabinet and removable therefrom, such tray being intended to receive dishes containing courses of a meal. Also, there is provided heating means which can be selectively turned-on and turned-off for heating the food which is to be heated-up. The tray is provided with means defining a region having a substantially horizontally accessible heating chamber intended for the reception of the food which is to be heated-up. The heating means associated with the tray and which can be turned-on upon insertion of the tray into the cabinet, extends substantially horizontally into the inner compartment of the cabinet, so that such heating means can be introduced into the heating chamber upon insertion of the tray into the cabinet.

Abstract: A food warmer includes a plurality of trays and associated lamps mounted on a frame for rotation in unison about a stationary standard. Each lamp is arranged above each respective tray to project heat downwardly only into the tray with which it is associated. The trays are pivotally supported on the frame and a switch associated with each tray is closed by pivotal movement of the tray upon placement of food on the tray to energize the lamp associated with the tray. A rotary connector is disposed between standard and frame, so that current can be supplied to each lamp regardless of the rotary position thereof. Each tray is detachable from the frame for cleaning and a switch override is selectively disposed between the tray and housing to prevent closing of the switch and energization of the lamp when necessary.

Abstract: A stand for holding one or more heatable hair curlers or curling irons has a well or receptacle for each curling iron, each well having two contact poles connecting through normally open switches to a source of power to the stand. Each curling iron has a heating element thermally connected to a hair mandrel and electrically connected to separated electrical contact zones on the iron beyond a thermal insulating handle. The handle terminates remote from the mandrel in a reduced actuating tip that passes a restriction in a receptacle and moves a switch actuator to close the switches and supply current to the curling iron heating element, through the contact poles and contact zones. Removal of the iron from the stand closes the switches and no current flows.

Abstract: A rotatable heating unit for supporting food receptacles is convertible to a rotatable unheated unit, and comprises a base, and a circular support rotatably mounted on said base, having a depressed central surface. Means are provided for heating said depressed central surface and thereby heating food receptacles supported thereon. A removable cover substantially fills the depressed central portion of said support to form with the surrounding portion of said support a substantially level unheated surface for supporting food receptacles. Means are provided for spacing said cover from said depressed central surface.