Abstract: A heat treatment control system to cure a photoresist that is deposited upon a semiconductor substrate is described. The heat treatment system has a hot plate with a heating element and temperature sensing devices that are in close proximity to the semiconductor substrate. The heat treatment system also has a controlling device that will selectively provide an electrical power source to the heating element to heat the semiconductor wafer. The coupling of the heating element to an electrical power source is determined by an electrical signal from one of the temperature sensing devices that have been conditioned and compared to a set temperature signal to provide an error signal. The controlling device will examine the error signal and adjust the temperature. An over temperature alarm circuit is connected to the second temperature sensing device.

Abstract: A heating control apparatus for use in a heating system having heaters for heating at least one location and temperature sensors for measuring the temperature of each location is disclosed. The heating system is connected to an electricity supply having a tariff which varies with time. The heating control apparatus comprises a data receiving arrangement for receiving data on the tariff and weather prediction information. A selector is provided which is operable by a user to select the desired temperature for each location and a desired time and duration of the desired temperature. A controller includes a memory for storing information on the thermal characteristics of each location and the heaters and is responsive to the data, the measured temperature and the temperature selected by the user as well as the stored information to determine the times at which the heaters are to be energised. The controller then controls the heaters in order to achieve the desired temperature in each location.

Abstract: An oven for heating food includes a refractory slab for placing a food item to be heated thereon. The refractory slab is preheated to a preselected temperature by a first electric resistance heating element disposed below the slab. The oven also includes a second electric resistance heating element and circulating fan disposed above the food to be heated. When food is cooking, electrical power is switched from the first heating element to the second heating element so that both heating elements are never operated at the same time. Food is cooked by the dual action of conduction from the slab and convection from the second heating element and fan. After the food is cooked, power is switched back to the first heating element to maintain the slab at the preselected temperature.

Abstract: In accordance with the present invention, a vending machine has one or more programmable cook cycles for use with one or more heat sources in cooking a food package to be dispensed to the customer. In one embodiment of this invention, each cook cycle includes a start time and a duration. Each cook cycle is associated with a heat source and a product code indicating the type of food to be cooked. Initially, cook cycles are copied into a random access memory from default cook cycles hard coded in the software program code and stored in electrically erasable programmable read only memory (EEPROM) of the vending machine controller. The cook cycles in RAM can be over written by an operator for the various type of foods to be cooked. The cook cycles in RAM are used by the vending machine to automatically cook a food product selected by a customer, without any further inputs.

Abstract: The positive temperature coefficient thermistor heater is composed of a positive temperature coefficient thermistor element, and electrodes formed on the both principal faces of the thermistor element. At least one of the electrodes consists of split electrodes. The positive temperature coefficient thermistor heater device has a positive temperature coefficient thermistor heater in which at least one of the electrodes consists of split electrodes, and radiator plates disposed on the both principal faces of the thermistor element. The split electrodes of the positive temperature coefficient thermistor heater are equal in area to each other, or different from each other.

Abstract: The temperature of each heating element among a plurality of heating elements is regulated by opening and closing a relay associated with each heating element in response to the monitored temperature of each heating element. The voltage across all of the relays is interrupted simultaneously at predetermined intervals, and each relay is opened or closed only when the voltage is interrupted. This permits the use of relays having lower current ratings and also extends relay life.

Abstract: A device and a method for compensating for temperature fluctuations for maintaining the warmth of a cooker having an inverter circuit, which has a system controller which obtains a final compensation data by processing a temperature compensation data outputted from a compensation temperature selection section and a present temperature detected by a temperature detecting section. The system controller outputs a driving signal to drive a bottom heater, a top heater, and a side heater of the cooker according to a calculated final compensation data.

Abstract: A temperature control method in a rapid heat treatment apparatus comprising simulatively heating dummy wafers in a process tube and previously detecting and grasping by temperature sensors a wafer temperature rising pattern, a heater temperature rising pattern and an internal atmosphere temperature rising pattern, arranging wafers to be processed in the process tube, detecting a temperature of each zone and that of each heater element by the temperature sensors, upon heating the wafers, and controlling each heater element on the basis of the detected temperatures and the wafer, heater and internal atmosphere temperature rising patterns by a controller to rapidly and uniformly raise the temperature of each wafer until the temperature of the wafers in each zone reaches the intended one and becomes stable.

Abstract: An improved heat pump system of the type having a thermostat capable of generating at least three stages of demand signals, outdoor and indoor heat exchange coils, at least one fan, a compressor, an expansion device, with the flow of refrigerant being reversible for purposes of selecting between heating and cooling modes of operation and a supplemental heater having a plurality of supplemental heating units for further heating an air stream passing over the indoor coil through an air supply plenum to supply air to a comfort space. An improvement in this system where each of the supplemental heating units has a unique heating capacity; a combination of supplemental heating units can be selected that is responsive to a demand for heat from the thermostat; and the selected supplemental heating units are turned on appropriately so that the level of heat demand by the thermostat is provided.

Abstract: A method for controlling temperature in thermal processing equipment having a processing chamber containing members to be processed. The method comprises the steps of heating a plurality of zones of the processing chamber by heaters provided in the zones, respectively, measuring periods of time which elapse until temperatures in the zones increase from a predetermined value to at least one reference value, obtaining time differences among the periods measured, and storing the time differences into a memory, and adjusting timings of heating the zones by the heater, thereby to reduce the time differences.

Abstract: A temperature control system for a self-cleaning oven and a method for operating in a clean mode for a self-cleaning oven are provided. The control system and the method allow for cleaning of the oven in a clean mode between a maximum temperature and a minimum temperature over the time period required for cleaning the oven. The maximum temperature is reached at least once during the clean mode and is, preferably, cycled to reach the maximum temperature a number of times during the clean mode. As a result of the cycling during the clean mode, a significantly reduced average temperature is required for cleaning of the oven during its self-cleaning operation.

Abstract: This Measuring Method of the electric power consumption of the Inverter Cooker enables automatic measurements of the electric power consumption for the keep-warm function, whether actual keep-warm temperature is set somewhat higher or lower, so that the productivity of the Cooker will be improved and judgement for defects of the keep-warm heaters made easier.

Abstract: Method for the storage and controlled supply of electric energy for discontinuous loads in steelworks and in particular for metal melting systems and rolling mills, the method comprising at least one main supply line (18) connected to a main supply source (11) of electric energy and a plurality of loads (12-13-14-114-20), whereby the level of maximum active power supplied by that main supply source (11) to the steelworks is limited by a sub-station (27) to a level "P.sub.0 " lower than the peaks of maximum absorption by those loads (12-13-14-114-20), the method comprising at least one accumulation line (16) connected in parallel to the main supply line (18) and supplying at least one storage assembly (17), which is connected to the loads (12-13-14-114-20) through a secondary supply line (19).

Abstract: An electric coffeemaker includes a first electric heater for heating water for brewing the coffee. A carafe is supported on a base portion of the housing of the coffeemaker. A second electric heater is mounted in heat transfer relation with the base portion for keeping the base portion warm when a coffee-laden carafe is positioned thereon. The operation of the second electric heater is controlled to reduce the heat delivered to the base portion when a relatively lesser quantity of coffee has been brewed and to increase the amount of heat delivered to the base portion when a relatively greater quantity of coffee has been brewed. The operation of the second heater may also be varied to satisfy specific consumer taste preferences.

Abstract: A method of controlling a current defrost cycle for an outdoor coil of a heat pump system, the heat pump system having a plurality of supplemental heating elements for heating an air stream passing from an indoor coil to an air supply duct during defrost operation, wherein an initial quantity of supplemental heating elements energized is a function of a most recent previous defrost cycle.

Abstract: A method of controlling a current defrost cycle for an outdoor coil of a heat pump system, the heat pump system having a plurality of supplemental heating elements for heating an air stream passing from an indoor coil to an air supply duct during defrost operation, wherein an initial quantity of supplemental heating elements energized is a function of a most recent previous defrost cycle. The initial quantity of supplemental heating elements is energized upon initiation of a defrost cycle. Whether the initial quantity of supplemental heating elements provided is insufficient or excessive is determined. At least one of the supplemental heating elements is deactivated if the initial quantity of supplemental heating elements being provided is excessive.

Abstract: A drying apparatus for use in a photosensitive material processing system, which is designed so that nonuniformity of drying in a direction intersecting a belt-shaped photosensitive material, e.g., a photographic negative film, photographic paper, etc., is eliminated, and the overall electric power capacity of the system is minimized. A plurality of electric current heaters (44.sub.1 and 44.sub.2) are disposed in parallel in a direction intersecting belt-shaped photosensitive materials (F.sub.1 and F.sub.2) transported, and each electric current heater is individually current-controlled to change the temperature distribution of the heated air, thereby compensating for the nonuniformity of drying of the belt-shaped photosensitive materials (F.sub.1 and F.sub.2) in the lateral direction, for example. The electric current heaters (44.sub.1 and 44.sub.2) are individually current-controlled by making the current input time different for each electric current heater.

Abstract: A method and apparatus for programmably controlling a cooking appliance. In addition to PREHEAT, COOK, and HOLD modes, the control is operable in a PROGRAM, SPECIAL PROGRAM and TEST mode. In PROGRAM mode a user sets parameters for a plurality of products. In SPECIAL PROGRAM mode global or system oriented settings are made. In TEST mode, individual components may be tested under operation of a control panel. Data may be logged to record usage for individual components and system information. A door sensor override may be used to turn OFF desired components when a door is open. A vent may be opened to reduce humidity at various programmed times during a COOK cycle or based on sensed parameters (e.g. humidity in the cooking chamber. A speaker may provide alarms that are programmable in volume and frequency for different products or events. Restricted access to different program or test modes is disclosed.

Abstract: An electrical control scheme which permits operating power for a microwave oven and a second electrical appliance, such as a refrigerator, to be withdrawn from a single electrical outlet utilizes electrical contacts across which a voltage differential is generated when the oven is in operation and includes wiring connected between the second electrical appliance and the microwave oven. The included wiring conducts electrical power to the second electrical appliance from the power cord of the microwave oven, and the control system further includes a relay having a normally-closed switch.

Abstract: A temperature regulating control unit and method of making the same are provided, the unit comprising a RTD temperature sensor, a unit for applying electrical signals to the sensor, and a microcomputer for receiving digital signals from the sensor in relation to the temperature being sensed by the sensor, the unit for applying electrical signals to the sensor applying a varying voltage to the sensor.

Abstract: A heat treatment system is fabricated from a loading section, a heat treatment section and a outlet section integrated with one another, and the heat treatment section comprises a transfer mechanism provided between the loading section and the outlet section for successively transferring silicon wafers, a heating unit provided along the transfer mechanism for heating the silicon wafers, and a cooling unit provided along the transfer mechanism and closer to the outlet section than the heating section for cooling the silicon wafers so that the silicon wafers are continuously treated with heat for annihilating thermal donors produced from oxygen during the growth of a silicon crystal without any handling by operators.

Abstract: A device and a method for shrinking heat recoverable sleeves for covering cable joints comprising a heating device the interior of which has a plurality of independently energizable heating elements and at least one sensor and a control circuit or control circuits which are connected to the heating elements and the at least one sensor. The control circuit is arranged to produce a uniform and then a non-uniform temperature profile within the heating device unless the initial temperature within the heating device is above a given temperature (e.g.) 30.degree. C. in which case the control circuit waits until the temperature within the heating device falls to below the given temperature before producing the temperature profiles whereby sleeved cable joints of a uniform quality are produced by avoiding air entrapment within the sleeve during the shrinking process.

Abstract: A heater apparatus includes an electrically insulative base plate and a plurality of independent resistors, extending along a length of the base plate, for producing heat upon electric energization thereof. A temperature detecting element detects a temperature of the base plate, and a controller controls a supply of electric power to the plurality of independent resistors so that the temperature detected by the detecting element approaches a predetermined temperature. A selecting device selects at least one of the resistors to be energized to change a resultant resistance of the selected resistors in accordance with an output of the detecting element.

Abstract: In an apparatus for detecting turn-on state of plural heaters including an electric power source for supplying electric power to the plural heaters, a controller controls the electric power source to be turned on and off so that each of the plural heaters is turned on and off in a predetermined manner, and a current sensor measures the total current supplied from the electric power source to the plural heaters. Then, a comparator compares the total current measured by the current sensor with plural reference values different from each other and outputting signals for representing comparison results thereof, and a judging circuit judges turn-on or off state of each of the plural heaters based on the signals outputted from the comparators.

Abstract: A method and apparatus is disclosed which automatically adjusts the on-time of preferably quartz lamp heating elements in an oven having both quartz lamp and electric heating elements. In such an oven having dual heating elements, the temperature of the oven's cavity increases when numerous food items (loads) are rapidly cooked in succession. The present invention allows a dual heating element oven to automatically compensate for these increases in temperature by preferably shortening a predetermined on-time of the quartz bulbs. The on-time is continuously compensated using a microcomputer, dependent upon the current oven temperature. The microcomputer preferably uses at least two clocks to shorten the predetermined on-time of the quartz bulbs.

Abstract: Plural electrical loads supplied with power from a single source are monitored to detect defective loads. Each load is periodically individually energized and current delivered by the source is measured. Measured current for each load is compared with limit values to detect abnormal values. To overcome consequences of supply voltage fluctuations, supply voltage is also measured and admittance of each load is determined from measured current and measured voltage. The admittance value thus determined for each load is compared with limit values to detect abnormal values. Load monitoring of loads energized according to a control algorithm proceeds by periodic momentary suspension of energization according to the control algorithm and energization of selected individual loads.

Abstract: A system for controlling the temperature of a lamp annealer which system comprises a group of lamps for heating an article to be heated, a radiation thermometer for measuring the temperature of the article, and a lamp output conroller for controlling the output of the lamps based on the output of the thermometer, the controller having stored therein a target temperature control pattern.

Abstract: In a heat pump system having supplemental heat for application to the supply air during periods of defrost operation, a "cold blow" condition is avoided by turning on a supplemental heater and by sensing the temperature of the supply air and responsively turning on additional heat in stages when necessary to maintain the temperature level of the supply air at a comfortable level.

Abstract: A tankless, flow-through electric water heater whose housing is designed for modular application, where serially connected modules define the path of the fluid being heated, in this case water, through the heater from inlet to final outlet. Each module contains two separate chambers and each chamber is provided with an electric immersion type heating element. The first and last chambers will also have a temperature sensor which will signal an electronic temperature control system. The temperature sensor in the first and last chambers provides signal inputs to energize each heating element of each chamber for a period of time proportional to the temperature difference between first chamber and the desired set leaving temperature of the water, which is set by an adjustable temperature controller (potentiometer), included in this control system. This control system also has a minimum setting point for a "no flow" condition or for the prevention of water freezing, where extreme weather conditions exist.

Abstract: A temperature regulating control unit and method of making the same are provided, the unit comprising a RTD temperature sensor, a unit for applying electrical signals to the sensor, and a microcomputer for receiving digital signals from the sensor in relation to the temperature being sensed by the sensor, the unit for applying electrical signals to the sensor applying a varying voltage to the sensor.

Abstract: An electrical system for supplying power to an electrical resistive heater that heats the catalyst of a catalytic converter. The electrical system includes an alternating current generator that has an output winding and a field winding that is carried by the rotor of the generator. The rotor is driven by an engine on a motor vehicle. The motor vehicle loads, including a storage battery are supplied with current by a first bridge rectifier that is connected to the output winding of the generator. The resistive catalyst heater is supplied with current by a circuit that includes a step-up transformer connected between the output winding of the generator and a second bridge rectifier that feeds the heater. The system can be operated in a high power mode for supplying a higher level of power to the heater.

Abstract: A method and apparatus is disclosed which automatically adjusts the on-time of preferably quartz lamp heating elements in an oven having both quartz lamp and electric heating elements. In such an oven having dual heating elements, the temperature of the oven's cavity increases when numerous food items (loads) are rapidly cooked in succession. The present invention allows a dual heating element oven to automatically compensate for these increases in temperature by preferably shortening a predetermined on-time of the quartz bulbs. The on-time is continuously compensated using a microcomputer, dependent upon the current oven temperature. The microcomputer preferably uses at least two clocks to shorten the predetermined on-time of the quartz bulbs.

Abstract: A control system for dual oven resistance heaters (BAKE, BROIL) has opposite sides of each heater connected to a common side of one of a pair of SPDT switching relays such that no current flows to the heaters when both relays are in a common state of energization/de-energization. A microcomputer receives a signal from the oven temperature sensing and signals separate switching devices to selectively energize/de-energize one of the relays to switch on the desired heater. Separate comparators also receive the temperature sensor signal; and, in the event of failure of the microcomputer or switching devices with a heater "ON", the comparator is operative to bring the relays to a common state, preventing current flow to either heater.

Abstract: A circuit for controlling the energizing of heating elements (13), including transistors (12) for controlling the energizing of the respective heating elements, energizing start time counter circuits (22) for determining a delay time until the energizing of the respective transistors (12) is started, and energizing time counter circuits (23) for determining energizing time. Data are written to the respective counter circuits from the outside via a group of multi-bit, multi-stage latch circuits and a counter clock signal (8). The energizing start time counter circuits (22) are collectively and simultaneously caused to perform a count (subtraction) operation. Then, the energizing time counter circuit (23) is made to start a count operation at a point in time when each of the energizing start time counter circuits (22) holds a value of 0, and the transistors (12) start to energize each heating element (13).

Abstract: A cooking appliance adapted for energization by a standard domestic household power supply employs a power control arrangement which accommodates electric resistive heating units designed for operation at a maximum RMS voltage level less than the RMS voltage level of the output power signal of the domestic power supply. The power control system couples power pulses from the external power supply to the heating unit at one of a plurality of available pulse repetition rates, each repetition rate establishing a corresponding RMS voltage level for application of power to the heating unit. The repetition rate associated with the maximum user selectable power setting for the appliance is effective to apply an RMS voltage level to the heating unit which corresponds to the voltage level for which the heating unit was designed.

Abstract: A microwave sourced heat exchanger in an inverted, truncated frusta-pyramidal or frusta-conical shaped configuration. A heat conductive medium is carried within microwave transparent pipes toward a microwave source having one or more magnetrons along a split path of increasing parameter. The magnetrons sequentially operate in a cyclic pattern such that the respective magnetrons do not operate when their respective operating temperatures exceed their respective maximum safe operating temperatures. The sequential use of multiple magnetrons increases the efficiency and operating life of the magnetrons. The geometrical design of the microwave heat exchanger allows the heat conductive medium anywhere in the conduit to be directly exposed to microwaves. Further, the geometry of the microwave heat exchanger induces a thermal siphon when the heat conductive medium within is exposed to a microwave source placed at the exchanger's broader base.

Abstract: An electrically operable heating system which comprises a plurality of heating units has one or more control units for controlling the operation of each heating unit. Each control unit operates on the basis of two input signals (F) and (P). One (F) represents the maximum proportion of the power of the associated heating unit or units which can be made available at any time and the other (P) represents the fraction of that proportion required at a particular time. Also disclosed is a system in the switching of heater units is carried out in a random manner.

Abstract: This invention pertains to a controller for electric heaters for preheating temperature sensitive components of internal combustion engines operating in very cold climates. The controller reduces energy consumption by turning on the engine component heater no sooner than necessary for the object to achieve the desired temperature. The device monitors ambient air temperature and when it is cold enough, projects the rate of the change of temperature forward to predict the temperature at the time the engine must next be started. Using manufacturers' heater specifications, the air temperature ambient to the engine components and an heating function derived from heat conduction theory, the device calculates the amount of time required for heating the engine components and turns on the heater when the appropriate time arrives.

Abstract: Multiple heaters are calibrated and controlled by a microcomputer, and a multiplexer of this system. The heaters are sequentially sampled and resistance calculated from voltage and current measurements. The operator enters a temperature for the calculated resistance to establish a calibrated resistance value. During run, the computer energizes and samples each heater to calculate its resistance. The calculated resistance is divided by the calibrated resistance to determine a resistance ratio. A look-up table is stored in the computer having resistance ratios for corresponding temperatures. The computer compares the calculated ratio to that of the look-up table to determine actual heater temperatures. Based upon heater temperatures, the computer controls energization of the heaters until set points are achieved.

Abstract: A heat/process control is disclosed which takes advantage of the characteristics of some plastics in that they absorb medium wavelength infra-red heat waves in a comparatively wide range of temperatures (and therefore wavelengths). The heaters used in this equipment are of quartz-tube construction which can be used through a wide temperature range. Tests have indicated that lamp wattage and machine processing speed were mathmatically related. For plastics of different formulation and/or thickness a series of parametric curves exist. Each curve is resident in the machine control and can be incorporated with a simple selector switch. For a given plastic a mathmatical equation relating speed and heater temperature is selected. If an increase in speed is required, the target speed and associated temperature is calculated and then loaded into the controller.

Abstract: An Au/Si die attach method for attaching a die to a package including preheating the package, melting Au/Si preform in the package cavity, scratching the die onto the package cavity to form a die attach bond, and gradually cooling an Au/Si die bond by reducing heat supplied the package, so as to cool the package through a monotonically decreasing sequence of temperatures, where the package is maintained for a predetermined period of time at each temperature in the sequence. A heating block with segments supplies a decreasing amount of heat to the packages to let the die attach bond gradually cool. The packages are kept on top of the segments of the heating block for a predetermined period of time and each segment is heated to a specific temperature. The gradual cooling of the die attach bond decreases the thermal resistance and prevents the creation of voids in the die attach bond.

Abstract: An apparatus which provides selectively either constant power, constant current or constant voltage to the heating elements of the thermods. The soldering system power supply apparatus includes devices for monitoring and controlling individual temperature profiles of each soldering thermod heating element. A computerized arrangement controls the power to each thermod in a very accurate manner. For the purpose of adjusting the power to each thermod element as a function of its temperature and the desired temperature profile, a set of temperature sensors are coupled to each of the thermod elements for measuring its temperature. Similarly, a set of energy sensors are also coupled to each of the thermod elements for detecting the amount of electrical energy supplied to each thermod.

Abstract: In a capillary rheometer including: a furnace comprising a plurality of furnace zones and having a sample bore with a capillary connected to the lower end thereof; a plurality of heaters for heating the furnace zones thereby to heat a sample in the sample bore; and a plunger for extruding the heated sample through the capillary; a plurality of temperature sensors are provided for detecting the temperatures of the furnace zones, and the temperature characteristics of the furnace zones related to the temperature of the inner wall of the sample bore are obtained and stored in a controller.

Abstract: A stove for burning in electronic modules which incorporate a heatsink to radiate heat comprises for each module controlled electrical power supply circuits and locally controlled temperature regulators employing a controllable dissipator comprising a heat shunt. The heat shunt comprises a heat conducting body, an arrangement for placing the heat conducting body in contact with the heatsink of the module so that they cooperate thermally as a result of the resulting conduction of heat by contact, an arrangement for heating the heat conducting body and a heatsink adapted to dissipate heat from the heat conducting body to an external environment. The dimensions and the geometry of the heatsink of the shunt and the temperature and ventilation conditions of the external environment are adapted to enable a quantity of heat to be extracted from the shunt by its heatsink which is greater than the quantity of heat dissipated by the heatsink of the module.

Abstract: A heater control apparatus for use with a plurality of printers each having a heater, comprises a detection part for detecting occurrence of zero crossing of a voltage signal supplied from a power supply and for supplying a zero cross signal each time the zero crossing is detected, a signal part for detecting an ON state of a request signal, the request signal being turned ON when a heater of any of the plurality of printers is currently turned ON, a first control part for determining a delay time in accordance with a predetermined device number setting value such that a timing with which a heat-on signal is supplied to a heater of a subject printer lags by the determined delay time behind a timing with which the zero cross signal is supplied by the detection part, and a second control part for supplying a heat-on signal to the heater of the subject heater at a timing defined by the determined delay time only when the request signal is turned OFF, thereby preventing two or more heaters from being turned ON si

Abstract: A control system for regulating electrical power input to the resistive heating elements of an electric heating apparatus, including domestic cooking appliances, is provided which employs at least one piezoceramic relay device. The electrical power is applied with the piezoceramic relay device responsive to control signals and with the control circuitry being directly and ohmically connected to the power source. In one embodiment, the control system employs individual piezoceramic relay devices for power regulation to the individual heating elements while in different embodiments a single piezoceramic relay device regulates power input to a pair of the heating elements. A method of operating the controlled apparatus in such manner and an apparatus having such control system are also disclosed.

Abstract: A method and apparatus is disclosed for transferring electrical power to a balancer 14 without the need for a physical connection between the balancer and the power source 16 or the controller 12 and which also provides for data communication between a balancer 14 and a balancer controller 12.

Abstract: An image forming apparatus having a built in AC voltage control circuit which enables the apparatus to be used in regions of the world having commercial power supplies with different supply voltages. The AC voltage control circuit first compares the input voltage to a reference voltage and then performs a switching operation to ensure that the voltage supplied to the AC electric components of the image forming apparatus is the voltage necessary for operation of those components.

Abstract: A very inexpensive and compact circuit arrangement having low electrical losses and which supplies a load with energy from an AC voltage source by means of a switch-mode power supply unit (22). The load includes at least two partial loads (3, 4) and electric energy is supplied to one of the partial loads (3 or 4) through the switch-mode power supply unit (22) and, as desired, also to at least a second one of the partial loads (4 or 3) directly from the AC voltage source.

Abstract: An electrical logic circuit for incorporation in the common power supply system of an appliance including a plurality of electrical components which have intermittent power requirements comprises a system for designating the components as dominant and subsidiary components and circuitry to direct power to the dominant component preferentially and to the or a subsidiary component only in dependence on the instantaneous power requirement of the or a more dominant component. The logic circuit may include a standby facility to direct power selectively to the subsidiary component. The invention may be applied to an ironing system including a heatable iron as the dominant component and a heatable board as the subsidiary component.