Abstract: A fuser assembly for an electrophotographic imaging device includes a heater including a substrate, a resistive trace disposed and running along a length of the substrate for generating heat for fusing toner to a sheet of media when a current is passed therethrough, and at least three conductors for passing current through the resistive trace. The at least three conductors include a first conductor connected to a first end portion of the resistive trace, a second conductor connected to a second end portion of the resistive trace, and a third conductor connected to the resistive trace at a location between the first end portion and the second end portion thereof. A temperature sensor senses a temperature of an edge segment of the substrate. Based upon the temperature sensed, circuitry selects between the first conductor and the third conductor for passing current through the resistive trace.

Abstract: In bi-directional imaging, such as bi-directional printing, a driving mechanism scans a light beam through a scan path across an imaging window. A controller enables transmission of video data to a modulator when the light beam is positioned for imaging on the imaging window. Video data is transmitted to the modulator when the light beam is traveling in a forward direction or a reverse direction across the imaging window, whereby a modulated light beam is capable of producing an image when traveling in the forward or reverse directions. The controller adjusts scan durations or image rasterization rates to ensure that each scan is properly aligned with the prior and subsequent scan.

Abstract: A method for operating a torsion oscillator at its resonant frequency. The method performs an open-loop frequency sweep starting with nominal operation parameters saved from the factory or from a previous operation of the torsion oscillator. The sweep determines an open-loop resonant frequency and an open-loop drive level. A closed-loop resonant frequency sweep is performed and a closed-loop steady-state resonant frequency is determined. This frequency is used to calculate a closed-loop overshoot and a closed-loop steady-state drive level. The torsion oscillator is then operated in a closed-loop mode at the closed-loop steady-state resonant frequency and starting at the closed-loop steady-state drive level. Finally, the nominal operation parameters are updated and stored in non-volatile memory. The method minimizes the effects of ambient environmental conditions including air density on the steady-state operation of the torsion oscillator.

Abstract: A method for operating a torsion oscillator at its resonant frequency. The method performs an open-loop frequency sweep starting with nominal operation parameters saved from the factory or from a previous operation of the torsion oscillator. The sweep determines an open-loop resonant frequency and an open-loop drive level. A closed-loop resonant frequency sweep is performed and a closed-loop steady-state resonant frequency is determined. This frequency is used to calculate a closed-loop overshoot and a closed-loop steady-state drive level. The torsion oscillator is then operated in a closed-loop mode at the closed-loop steady-state resonant frequency and starting at the closed-loop steady-state drive level. Finally, the nominal operation parameters are updated and stored in non-volatile memory. The method minimizes the effects of ambient environmental conditions including air density on the steady-state operation of the torsion oscillator.

Abstract: A circuit includes a switching device for controlling a power signal to be applied to a heating device. A control circuit is configured for comparing a temperature signal, indicative of the temperature of the heating device, to a temperature setpoint to generate a gate pulse signal that controls the duration of the power signal to be applied to the heating device. The control circuit is further configured for comparing the duration of the power signal to be applied to the heating device to a minimum pulse duration and, if the duration of the power signal to be applied to the heating device is at least equal to the minimum pulse duration, providing the gate pulse signal to the switching device.

Abstract: A bi-directional electrophotographic raster imaging system that sweeps a modulated light beam across an imaging region of a photosensitive surface to create both forward-going and reverse-going scanlines of dot data on the imaging region, and which compensates for image misalignment that may be caused by varying the power used to drive a laser light source that generates the modulated light beam. An SOS photosensor detects the beginning of each scanline in both forward and reverse directions, outputting an SOS signal used to create both forward and reverse margins. When the laser power is varied, compensating data is used to correct the forward and reverse margins to keep them aligned (straight), even though the beginning of the scanline locations for both forward and reverse scans are affected in opposite directions by an increase or decrease in laser power.

Abstract: Laser printers are designed assuming the actual laser operates at nominal values which are the average or central values of a large batch of such lasers. The nominal values are determined and stored in permanent memory. Similarly, the values of the laser actually in the printer are determined during manufacture and also stored in permanent memory. Data to the laser is adjusted to correlate the output called for by the data with the differences in response of the laser of the printer by determining the optical output called for by the data using the nominal values stored and then finding the power needed to achieve the same output using the actual values stored. This is particularly useful with extreme duty cycles.

Abstract: Laser printers are designed assuming the actual laser operates at nominal values which are the average or central values of a large batch of such lasers. The nominal values are determined and stored in permanent memory. Similarly, the values of the laser actually in the printer are determined during manufacture and also stored in permanent memory. Data to the laser is adjusted to correlate the output called for by the data with the differences in response of the laser of the printer by determining the optical output called for by the data using the nominal values stored and then finding the power needed to achieve the same output using the actual values stored. This is particularly useful with extreme duty cycles.

Abstract: Compensation for beam separation of multiple laser beams of a laser printer simultaneously scanning a photoconductor drum is automatically made. The time for the lead beam to travel a predetermined distance is ascertained and then the separation time between the lead beam and one of the remaining beams is determined. When using only one light sensor, the time for the lead beam to travel the predetermined distance is the scan time of the lead beam. When using two light sensors, the time for the lead beam to travel the predetermined distance is the time for the lead beam to travel between the two light sensors, which define the predetermined distance, in the same scan. This determination of the time for the lead beam to travel the predetermined distance and its separation time from another of the remaining beams is continuously made for all of the remaining beams even during printing.

Abstract: A circuit for selecting a base memory to be accessed by a microcontroller in response to a command from the microcontroller. An input receives the command from the microcontroller. The command selectively instructs the circuit to reset the microcontroller and signal the microcontroller to access an internal memory as the base memory. Also, the command selectively instructs the circuit to reset the microcontroller and signal the microcontroller to access an external memory as the base memory. A reset output is used to send the reset signal to the microcontroller, and a memory select output is used to send a memory select signal to the microcontroller.

Abstract: The invention is directed to a method of calibrating a laser in an electrophotographic image forming apparatus used for producing a print image on a print medium. A laser having a selectively energizable laser beam output is provided. A rotatable optical device and the laser combine to define a movable projection path of the laser beam output. Rotation of the optical device results in movement of the projection path across a scan line overlaying a photoconductive drum. The optical device has a rotational acceleration upon initial rotation thereof with a ramp-up period during which the rotational velocity increases. A safe area is established in a portion of the scan line which does not overlay an image area on the photoconductive drum. The laser is energized and calibrated when the projection path is positioned in the safe area. The calibration is carried out during the ramp-up period of the rotating optical device.