Abstract: What is proposed is an electronic circuit for controlling the amount of AC power delivered to an inductive or resistive load which continuously measures the actual phase lag between the load current and applied voltage and automatically adjusts the firing angle to provide the desired amount of AC power. The circuit includes an auxiliary on/off input with soft start and independently adjustable time delays for the on and off functions and also incorporates an input for remote power level control and features a half-wave rectified mode which delivers pulsating DC power to the load.

Abstract: A recording apparatus in which a control unit utilizes a copy counter for plural purposes. The control unit also achieves other features such as securer jam detection, a constant operation regardless of the frequency of commercial power supply, securer timing and temperature control with limited number of sensors.

Abstract: A series resonant converter is interposed between an unregulated voltage source and an output circuit. The converter employs a pair of power switches each, when on, completing a series resonant circuit from the source to a resonant tank circuit including the primary winding of a transformer coupled to the output circuit. The power switches are alternately turned on and off so that sinusoidal current pulses alternately flow in opposite directions in the primary winding at a frequency dependent on input and output conditions. The current flowing in the resonant circuit is monitored and the power switches are additionally controlled to prevent turn on of one switch and turn off of the other when current is still flowing in the resonant circuit.

Abstract: In an apparatus for controlling the power factor of a power distribution system connected to inductive loads, banks of delta connected capacitors are added to or removed from the power lines of the power distribution system by a plurality of solid state switching devices which are under the control of a microprocessor. The solid state switching devices include optically isolated SCR devices that do not generate electrical interference and provide transient free operation. The microprocessor is also capable of calculating the power factor and displaying it on a digital readout.

Abstract: A heater control device in which a heater is made to double as a temperature sensor so as to eliminate the leading wires used exclusively for the temperature sensor. The heater control device includes a zero-crossing detector which generates a short duration pulse signal each time an AC power voltage is crossing the zero-level. The heater acts as a temperature sensor only for the short duration of the pulse signal.

Abstract: A regulated, low-voltage DC power source which draws energy from a standard AC outlet and uses a bank of lead-acid batteries for intermediate power storage.The power source features a multi-level charge-voltage controller which is automatically adjusted in function of the net current flowing in or out of the batteries. The charge-voltage control is accomplished by switching the charging current rectifiers on or off only at the zero-axis crossing in order to minimize voltage spikes, and only at every other crossing in order to minimize DC components in the secondary of the transformer. Charge current, load current and net battery current are separately metered in order to provide maximum efficiency and safety in the operation of the power source. A low-voltage-drop series regulator is relied upon to provide a 5 volt regulated output to the load from a 6 volt unregulated battery voltage source.

Abstract: A microcomputer is programmed to respond to the zero crossings of an AC power source to trigger a uniform pulse pattern of an integral number of AC cycles as the AC excitation to a heater element to maintain the temperature of the heater element essentially constant.

Abstract: A temperature control apparatus has a first comparator circuit for comparing the voltage corresponding to thermal data provided by a thermal sensor with a first reference voltage generated in synchronism with the zero crossings of an AC power source. The first comparator circuit generates a pulsative output voltage which is synchronous with the zero crossings of the AC power source. This output voltage causes a second reference voltage to be applied to a second comparator circuit in the form of a pulsative voltage. The second comparator circuit compares the thermal data voltage with the second reference voltage and generates a pulse signal. This pulse signal drives a trigger circuit which triggers a thyristor connected to an electric heater.

Abstract: In a circuit arrangement for controlling the operating temperature of the heating coil of an electric soldering iron, the resistance variation of the heating coil itself is to be evaluated at lowest possible cost of circuitry and doing away with a thermocouple sensor that used to be arranged in the region of the soldering bit or of the heating coil, at high mechanical cost. To this end, a precision resistor is inserted in the heating circuit and a TRIAC switching element connected between the latter and the heating element, which is switched open by a comparator circuit as a function of the voltage drop at the precision resistor or which lets through only the pulses of a pulse generator circuit required for measuring the switch-on threshold, which pulse generator circuit is synchronized via a null detection circuit for null passage of the AC voltage.

Abstract: A sample of the voltage magnitude across a load, connected in series with an A.C. source and a load-current-flow-control subcircuit, is taken during at one of the time intervals when load current flows during a source waveform cycle. The sampled load voltage is compared to a reference level and the difference in magnitude between the sampled and reference voltages is integrated, with respect to time, to provide an adjustment signal. The adjustment signal is provided to a subcircuit for timing the conduction period of the load-current-flow-control subcircuit, by varying the conduction-termination time after each conduction-commencement (at each source waveform zero-crossing) to vary the selected one of the half-cycle-average (mean absolute deviation--MAD) or RMS voltage magnitude across the load to a value such that the sampled load voltage magnitude is substantially equal to the selected reference voltage magnitude.

Abstract: A circuit for controlling the energization of an electrical load from an AC source. The circuit has a pair of DC lines, and means is provided for rectifying the AC output of the source to apply a DC voltage across the DC lines in the form of a full wave rectified sinusoidal signal. Signal switching means for connection between the DC lines and the load establishes a conductive path therebetween during a variable time interval when the voltage applied by the full wave rectified sinusoidal signal exceeds the voltage across the load, and means including the switching means is provided for chopping the full wave rectified sinusoidal signal to apply pulses to the load during the variable time interval at a frequency which is high with respect to the frequency of the signal.

Abstract: A heater control circuit functions in conjunction with a suitable heating coil to provide precision, automatic temperature regulation. The combination of heating and temperature sensing functions into a single system results in a two-wire heater regulator control circuit in which a continuous excitation voltage and a power voltage can be simultaneously present at the heater coil. Temperature of the heater is established by continuous excitation and sensing independent of the occurrence of power for heating. A short circuit protection circuit is responsive to an electrical short in the heater coil (which significantly changes its resistance with temperature) and disables the power voltage.

Abstract: A non-continuous sensing device for a temperature control including A.C. power switching element, a zero-crossing detector, a temperature sensor and a trigger pulse generator for generating a trigger pulse used to trigger the A.C. power switching element according to an output of the temperature sensor. The zero-crossing detector generates a pulse signal each time the instantaneous absolute value of the A.C. power voltage decreases to a value equal to or smaller than a predetermined value. The temperature sensor and the trigger pulse generator are kept active only for the duration of the pulse signal generated by the zero-crossing detector, thereby reducing the energy consumption and physical size of the entire device.

Abstract: A reverse-phase-control power switching circuit provides for controlling the flow of current through a load, from an A.C. source, and includes circuitry for limiting the in-rush current for a load having a variation of resistance due to initial turn-on phenomenon. Load current is enabled to flow at each zero crossing of an A.C. source, connected in series with the load and the switching circuit of the present invention. Load current is terminated at a time, prior to the next source waveform zero crossing, to either maintain a substantially constant current conduction angle for a load with a substantially-constant steady-state resistance, or to limit load instantaneous current to a maximum level, set to a value somewhat greater than the desired normal load current, during low-load-resistance in-rush time intervals.

Abstract: Apparatus for fusing a toner image to a support by means of heat and pressure. The fuser apparatus includes a heated fuser member which contacts toner image carrying supports moved along a path. A sensor is spaced from the fuser member for sensing the temperature thereof and for producing a signal representative of the temperature. Logic and control means connected to the sensor maintains the temperature of the fuser member within predetermined limits and interprets a sudden large drop in the temperature sensed as a jam condition caused by a support deviating from its path of movement and interposing between the fuser member and the temperature sensor.

Abstract: A coronode for use in an electrophotographic apparatus has one end thereof coupled to a high electrical potential output of an electrical transformer for use in generating a corona discharge current. A tap from another terminal of the transformer is coupled to another end of the coronode to establish a small EMF between the ends of the wire that is used in resistance heating of the coronode.

Abstract: An electronic control circuit for controlling the power applied to an electronic component such as a heater element or an electric winding for a motor. This is effected by measuring variations of the resistance of the component caused by the power flow therethrough. In a preferred form, the circuit has two operational amplifiers, one of which is a voltage comparator and summing amplifier to sum various signals, one being representative of the resistance of the component, the other amplifier operating as a monostable multivibrator. The component, which may be an electric heater for energizing through a switch controlled by the second amplifier. The resistance measurement is effected during the inflection point of the applied AC voltage. The heater is then energized for a full wave of the AC input. During every inflection point the resistance measurement is updated. A modification of the circuit includes a second heater disposed closely adjacent to the object to be heated to serve as an anticipatory circuit.

Abstract: A method and apparatus are described for controlling the temperature of a heated wire, such as on a wire sealer for plastic film. Temperature control is based upon measurements of changes in the resistance of the wire as it is heated, through bridge circuit and microprocessor techniques.

Abstract: Control system which measures overshoot or undershoot time of a controlled variable with respect to a set value and adjusts a proportional count if the overshoot or undershoot time period exceeds fixed values. The proportional count is used to control the system output in a proportional manner, such as supplying k out of every n cycles of power, where k represents the proportional count. To prevent excessively long periods of overshoot or undershoot, an overlimit detector provides adjustments of the proportional count when the overshoot or undershoot measured time exceeds an overlimit value.The control system has general applicability but is described in the temperature control of a fuser hot roll such as used in electrophotostatic copiers.

Abstract: The automatic temperature control device for an electric appliance such as an electric blanket comprises a heater element, a sensor made of a thermosensitive material having an impedance, which changes as the temperature varies, for detecting the temperature of the heater element, switching means for regulating the supply of electric power to the heater element, and a plurality of electric circuits for driving the switching means in response to the output signal from the sensor. The plurality of electric circuits function to prevent the sensor from being polarized and to detect a temperature signal by applying thereto an alternating current, to detect a failure occurring in the electric circuits in synchronism with zero-crossing pulses, and to detect a failure occurring in the switching means, thereby assuring a safe operation of the automatic temperature control device against the occurrence of any failure.

Abstract: A phase control circuit, for energizing lower voltage loads and the like from a higher voltage A.C. source, utilizes power switching means in series with the load across the source. The load voltage and current are sampled and compared to reference values to determine if the load resistance is less than or greater than a desired value and the output voltage of an integrator is adjusted accordingly. The integrator output voltage establishes the time, after each source waveform zero crossing, at which the power switching device enables load current flow. A reset circuit prevents the power switching device from conducting in the event that a line zero crossing is not properly detected, to preclude damage to the switching device and/or load overvoltage. A circuit is also provided for gradually increasing load current at start-up to limit inrush currents to the load.

Abstract: A power regulating device which maintains a constant rms voltage across a load by periodically interrupting the application of voltage to the load for a predetermined number of cycles. To accomplish this, a functional solution to the equation which describes the relationship between the rms line voltage developed across the load and the rms voltage of a desired control set point is continuously provided. The solution of this equation is obtained by squaring a sampling of the applied load voltage, subtracting the square of the desired control voltage, and then integrating over time the difference therebetween. When the resultant time integral reaches a predetermined constant value, the voltage applied to the load is interrupted for a predetermined number of half or full cycles.

Abstract: An electrical resistance heater controller is provided with a plurality of circuit branches connected in parallel with each other and in series with a heating element and an external AC power source. Each circuit branch includes the series connection of a capacitor and a solid state switch. The switches are controlled by a gating device to switch during the zero crossing of the AC source voltage waveform. Power delivered to the heating element is controlled by varying the amount of series capacitance in the circuit.

Abstract: The disclosure is directed to an improved electromagnetic cooking apparatus which is so arranged that the maximum voltage to be impressed to a switching transistor employed in it may be lowered to a desired level for a stable operation at high reliability.

Abstract: An electronic switching system for inductive loads in A.C. circuits, comprising a triac switch in series with an inductive load such as transformer or motor, etc. across an A.C. voltage. The control voltage for the triac switch is provided by a smaller, lower power triac driver, which has a light emitting diode controlled by an optically isolated transistor. The optically isolated transistor is provided with electrical pulses each a half cycle of voltage by means of a zero crossing detector. Since it is impossible to know precisely what the power factor of the load is, the triggering of the triac driver is provided at zero voltage on both the upward and downward crossing. These pulses, amplified by the transistor, control the triac driver. The load current will lag the voltage by some angle, dependent on the power factor, and the current will stop at its zero point.

Abstract: An apparatus and method for regulating alternating current electrical power conducted to an electrical load wherein a gate control bidirectional semiconductor switch is controlled by a sensing circuit which includes feedback elements for responding to fluctuation in voltage supplied from a power source and in current demanded by the load for maintaining a predetermined average voltage delivered through the apparatus and in accordance with the method.

Abstract: A power control method and apparatus maintains a constant average power at an electrical load, such as a fuser in an electrophotocopy machine. A power monitor measures the average power delivered to the load and compares the measured power to a predetermined power. A digital network receives an input signal from the power monitor and controls the coupling of power from an ac source to the load. When load power is less than a predetermined level, the digital network couples every half cycle of the ac power source to the load. When the load power is equal to or greater than the predetermined power, the digital network couples every third ac half cycle to the load. As a result, only half cycles of sequentially opposite polarity are coupled to the load.

Abstract: A copier fuser roll's temperature is accurately maintained by supplying selected half-cycles of current from a power supply to a heater in accordance with signals from a temperature sensor. Each sequential half-cycle is assigned a unique digital input number which accesses a table of digital output numbers having values chosen to correspond to one or more half-cycles. Sensor signals are sampled and digital temperature error numbers, determined by the fuser roll temperature and a desired roll temperature, are derived. The temperature error and output numbers are compared and, whenever a comparison occurs, the corresponding half-cycle of current operates the heater. Thus, depending upon the difference between a desired and the actual roll temperature, variable numbers of evenly spaced complete half-cycles, having a total positive-to-negative ratio approaching unity, are selected.

Abstract: Electronic sensor on/off switch for a load connected to an a-c supply network includes a controlled semiconductor switch connected in series with the load, a sensor for switching the load on and off, a control circuit connected from the sensor to the switch, the switch being addressable by the control circuit in a conducting state with the load switched on by a signal holding the switch in the conducting state at the zero crossing of a current passing through the load, and in a non-conducting state with the load disconnected by a signal switching the switch into the conducting state for switching on the load at the zero crossing of an output a-c voltage at the switch, a power supply circuit connected to the control circuit, a two-terminal voltage limiting network connected in a series circuit with the switch for generating an amplitude-limited a-c voltage if the switch is conducting, an inductive converter connected to the two-terminal voltage limiting network, a terminal producing a reference potential point

Abstract: A power control arrangement for controlling the power output of a resistive heating element of the type having a fast thermal response time and a highly variable resistance with temperature. The power control arrangement includes a plurality of operator selectable power settings and an electronic switching system responsive to operator selection of these settings to rapidly couple and decouple a power supply to the element. The switching action is selected to permit rapid heat up of the element without causing an unacceptable current to flow and to prevent excessive cooling of the element after it reaches operating temperatures during steady state operation.

Abstract: Electronic sensor on/off switch for a load connected to an a-c supply network, including a controlled semiconductor switch connected in a series circuit with the load, a sensor for switching the load on and off, a control circuit connected from the sensor to the switch, the switch being addressable by the control circuit in a conducting state with the load switched on by a signal holding the switch in the conducting state at the zero crossing of a current passing through the load, and in a non-conducting state with the load disconnected by signal switching the switch into the conducting state for switching on the load at the zero crossing of an output a-c voltage at the switch, a power supply circuit connected to the control circuit, a current transformer having a primary and a secondary winding and being operable in saturation, the current transformer being connected in series with the switch, the control circuit including a first rectifier being coupled to the secondary winding and having an output producin

Abstract: A vibrating compressor wherein an alternating voltage is applied from a d-c power source to a drive coil vibrating in a magnetic field via a d-c/a-c converter circuit is disclosed. An alternating voltage of a square wave form is applied to the drive coil of the vibrating compressor in such a manner as to avoid the timing at which a counter electromotive force generated in the drive coil intersects with zero level.

Abstract: Induction heating apparatus using gate-controlled switching devices includes a zero crossing point detector for detecting the occurrence of each zero crossing point of high frequency energization current, and a timing circuit which provides timing action in response to the detected zero crossing point. The timing action is controlled by a power control circuit which detects the level of energy delivered to a load within a range from the inherent turn-off time of the gate-controlled switching devices to a desired value.

Abstract: A power supply for generating a high unidirectional voltage at a charging electrode of an electrostatic spray coating apparatus has circuitry for sensing the magnitude of current flow to the electrode and for controlling application of an input voltage to the power supply in accordance therewith to control the magnitude of the high voltage. The arrangement is such that whenever the current flow is less than a predetermined value all cycles of the input voltage are applied to the power supply, but whenever the current exceeds the predetermined value only a limited number of the cycles are applied to the power supply. In this manner, the danger of arcing between the electrode and an article being coated is eliminated or at least significantly reduced.

Abstract: A solid-state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by a mechanical toggle control switch for close simulation of magnetic circuit breaker operation. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit, except the static power switch branch, between the source and the load, to provide a high degree of fail-safe protection for the apparatus. The power continuity feature includes means for zero crossover synchronization both upon power-up and power-down conditions. A circuit lockout feature is used so that on power-up or turn-on, operation is delayed until the occurrence of an internal power-ready condition. On power-down or turn-off, there is means for circuit retention subsequent to switch opening and internal power removal in order to accomplish load turn-off at a desired zero crossover point of the load power through the power switch.

Abstract: A solid state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by mechanical toggle switch for close simulation of magnetic circuit breaker operation in three phase or other multiphase systems. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit except the static power switch branch. The control switch is located between two of the supply voltage phases and the power supply for the control circuitry. The correct zero crossover of one phase is utilized to produce turn-on at zero degrees of that one phase while the other two phases are respectively at minus 120.degree. and plus 120.degree. without any significant impairment of overall circuit breaker performance. An overcurrent protection system is included that uses optical isolators with reduced sensing voltages developed directly from terminals of the power switch elements.