Abstract: A power supply control system for a fuser assembly in an electrophotographic apparatus includes a power supply and a fuser assembly. The power supply includes a first electrical path designated for a fuser assembly that operates at a first voltage and a second electrical path designated for a fuser assembly that operates at a second voltage. The fuser assembly is configured to operate at a select one of the first voltage or the second voltage and is connected to the first electrical path if the fuser assembly operates at the first voltage, and the fuser assembly is connected to the second electrical path if the fuser assembly operates at the second voltage. The first and second electrical paths allow different device features including power limiting devices such as fuses, switches, relays, etc., to be placed in each path.

Abstract: A plurality of universal fuser heating apparatus embodiments are provided, each of which is capable of receiving any one of a number of input AC line voltages falling within at least two AC line voltage ranges. In each embodiment, the fuser heating apparatus has a first, low effective resistance corresponding to AC line voltages falling within low AC line voltage ranges and a second, high effective resistance corresponding to AC line voltages falling within high AC line voltage ranges.

Abstract: A plurality of universal fuser heating apparatus embodiments are provided, each of which is capable of receiving any one of a number of input AC line voltages falling within at least two AC line voltage ranges. In each embodiment, the fuser heating apparatus has a first, low effective resistance corresponding to AC line voltages falling within low AC line voltage ranges and a second, high effective resistance corresponding to AC line voltages falling within high AC line voltage ranges.

Abstract: A power supply circuit receives and rectifies a three phase power source. A first capacitor is coupled to filter and store the rectified three phases and supply the stored energy to a DC/DC converter. The first capacitor is large enough, when all three phases are present, to filter the rectified input power and supply rated voltage to the DC/DC converter between peaks in the phases, but not too large as to adversely affect the power factor. However, when one phase drops out, additional capacitance is required to maintain rated voltage to the DC/DC converter during the periodic absence of the one phase. Thus, a switch and a second capacitor are connected in series with each other and in parallel with the first capacitor. In response to absence of one of the phases, the switch is activated to couple the second capacitor to filter and store the rectified two phases and supply the stored energy to the DC/DC converter.

Abstract: A circuit compares a difference between first and second voltages to a predetermined voltage. The circuit comprises an amplifier having first and second inputs. First and second capacitors are each coupled at one end to the first input of the amplifier. The first capacitor is charged with the first voltage and subsequently discharged. The second capacitor is charged with a first reference voltage and subsequently discharged. Third and fourth capacitors are each coupled at one end to the second input of the amplifier. The third capacitor is charged with the second voltage and subsequently discharged. The fourth capacitor is charged with a second reference voltage and subsequently discharged.

Abstract: A temperature compensated overcurrent and/or undercurrent detector monitors current through a solenoid or other load and signals when the load current exceeds an upper limit or falls below a lower limit. Such a signal may indicate a failure of another circuit which supplies the load current via a load transistor. This other circuit which supplies the load current is temperature compensated, and likewise the detector is temperature compensated so it can be set to signal an overcurrent or undercurrent condition when the load current varies a small amount from a predetermined range. The load transistor has an on-resistance which passes the load current and varies with temperature. The temperature compensation for the detector is provided in part by two pilot transistors which are integrated with the load transistor such that as the load transistor heats-up due to the load current passing through the on-resistance, the pilot transistors heat-up due to heat conduction from the load transistor.

Abstract: A temperature compensated control circuit includes a load transistor which passes the load current and has an on-resistance which varies with temperature. To provide temperature compensation, first and second pilot transistors are integrated with the load transistor such that as the load transistor heats-up due to the load current passing through the on-resistance of the load transistor, the first and second pilot transistors heat-up due to heat conduction from the load transistor. Each of the pilot transistors has an on-resistance which varies proportionally or similarly to the on-resistance of the load transistor. A first current source supplies a first level of current to the on-resistance of the first pilot transistor to develop a first reference voltage, and a second current source supplies a second level of current to the on-resistance of the second pilot transistor to develop a second reference voltage.

Abstract: A latch (29) is set by a clock (33) to turn on power switch (FET 5). The latch (29) is reset by high voltage comparator (21), by a 50 percent clock delay (35) and by a low-voltage-to-charging-current comparator (19). The voltage at turn-on is compared with a up-ramping reference (15) until it equals an operating reference (17). A temporary delay (pulse circuit 39 and gate 37) is provided before the low voltage comparison can be effective. The delay prevents response to parasitic effects across the power switch (5). Excess drive is prevented resulting from low output currents and malfunctions, and at turn-on.