Abstract: A method for controlling the media feed of a print media sheet in an imaging apparatus having a media feed roller includes selecting between using absolute positioning of the media feed roller and relative positioning of the media feed roller for various media feed roller moves.

Abstract: A method for performing drop placement by an imaging apparatus includes the steps of defining a matrix that identifies all possible drop locations at an output resolution; defining primary drop locations in the matrix for each color of interest based on predefined criteria; defining secondary drop locations in the matrix for the each color of interest; and establishing rules to assign input data received at an input resolution to particular locations of the primary drop locations and the secondary drop locations in the matrix.

Abstract: An interface device for attaching a printhead carrier to a carrier drive belt includes a belt holder attached to the carrier drive belt, and an isolator coupled between the belt holder and the printhead carrier. The isolator is configured to provide directionally dependent filtering of vibrations propagating to the printhead carrier.

Abstract: A printer (1) in which a first sheet (5) to be imaged by printhead (3) is followed by a trailing media sheet. The first sheet is stopped intermittently so that the printhead can traverse the first sheet to print a partial image. The trailing media sheet is stopped behind the first sheet and is moved intermittently until it reaches or is near nip rollers (9a, 9b). Exit rollers 11a, 11b, 11c, and 11d move the first sheet out of the printer. When the exit rollers and the nip roller move forward and backward together the first sheet may be exited before the nip rollers are reversed to align the second sheet. Alternatively, the first sheet may be moved backward during alignment. The intermittent movement of the sheets may be at different times and with the trailing sheet moved less times and longer amounts than the first sheet is moved.

Abstract: A method for performing drop placement by an imaging apparatus utilizing diluted color inks and full strength color inks includes defining a matrix that identifies all possible drop locations at an output resolution; defining primary drop locations in the matrix for at least one color based on predefined criteria, the at least one color including a diluted color; defining secondary drop locations in the matrix for the at least one color; and establishing rules to assign input data received at an input resolution to particular locations of the primary drop locations and the secondary drop locations in the matrix.

Abstract: A method of regulating a target system generates a plurality of digital signals which define a reference pulse train with a frequency dependent upon a reference signal. A target system to be regulated (such as a transport speed of a paper transport assembly in a printer) has an output in the form of a plurality of digital signals defining a feedback pulse train having a frequency. The frequency of the reference pulse train is compared with the frequency of the feedback pulse train. A control signal is generated dependent upon the frequency comparison, and is provided as an input to the target system.

Abstract: A method for determining the distance moved by a component (such as a printer paper-feed roller) operatively coupled to an analog encoder having analog first and second output signals. At least one of a first inverse signal which is the inverse of the first output signal and a second inverse signal which is the inverse of the second output signal is calculated. The distance moved by the component from a previous position is calculated using one of an ascending or descending region of the first or second output signal, wherein the previous position is the position of the component corresponding to a crossover level of two signals chosen from the group consisting of the first output signal, the second output signal, and the at-least-one inverse signal.

Abstract: A method of reducing printing defects in an ink jet printer including at least one printhead mounted to a printhead carrier for printing on a print media sheet, includes the steps of determining a vertical alignment error for at least one printhead and adjusting a sheet feed increment for the print media sheet based on the vertical alignment error.

Abstract: A method for reducing the effects of printhead carrier disturbance during printing with an imaging apparatus having a printhead carrier for carrying at least one printhead includes the steps of accelerating the printhead carrier from a first position in a first direction; printing with the printhead in the first direction; and changing a rate of acceleration of the printhead carrier for a subsequent accelerating of the printhead carrier from the first position in the first direction prior to a subsequent printing with the printhead in the first direction to phase shift the printhead carrier disturbance.

Abstract: A method of printing with an ink jet printer includes providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided.

Abstract: A scanning operation is synchronized with the motion of a scan mechanism. Encoder signals indicative of a position of the scan mechanism relative to a scan platen or an object being scanned are received. These encoder signals may include a single channel phase signals are channel A and channel B phase signals. Transitions of the encoder signals are detected. Scan pulses for triggering a scan operation by a scan element are generated based on transitions of the encoder signals. Differences in the encoder signal resolution and a desired scan resolution are compensated for in the generation of the scan pulses. A transfer signal is generated in synchronization with the scan pulses for controlling output of data from the scan element. Variations of the velocity of the scan mechanism cause variations of the frequency at which the scan pulses are generated.

Abstract: A control system in the form of an all-digital phase-locked loop controls movement of a DC motor. The control system includes a movement detector in the form of an optical encoder to detect movement of a DC motor. A digital phase detector compares output of a feedback signal from the movement detector and a reference signal. The digital phase detector is phase frequency detector that follows a describing function to model non-linear components of the reference signal. A digital loop filter then filters noise from the comparison signal and the filtered signal is amplified to control the DC motor. The phase frequency detector includes a state machine to track a time varying reference signal and selectively output a response to provide for system damping.

Abstract: A media eject system for a printer having an output tray includes an edge wing for supporting an edge of media exiting the printer, the edge wing movable between support and non-support positions. A kicker engages a trailing edge of media and moves the media into the tray. The kicker is movable between a retracted position and an extended position and operable to move the media into the tray by movement of the kicker from the retracted position to the extended position. A controller determines a print condition including at least one of a media type and a print format, and adjusts a position of the wing dependent upon the print condition.

Abstract: A device for controlling the velocity of an electric motor is provided. The device combines a traditional PI (Proportional+Integral) velocity controller with a robust mapping technique that estimates the velocity of the motor. The mapping technique is based on fuzzy logic methods, and provides a robust estimate of the motor's rotational velocity by using the motor current measurement and pulse-width modulated (PWM) voltage being applied to the motor. In one embodiment the device is combined with a calibration technique which ensures the proper calibration of the motor.

Abstract: A method for calibrating electric motors using current-sensing only is disclosed. The method involves applying a voltage in pulse-width modulated fashion for a short time to insure motion of the motor. Following startup, varying voltages are pulsed to the motor, switching polarity at regular intervals. The current generated in the motor by each level of voltage is measured. The data generated provide a reasonably accurate view of the properties of the motor, allowing for more precise velocity control.

Abstract: One method operates a pick motor and a separate feed motor to pick and feed a sheet for printing. Desired pick and feed motor velocities are obtained from respective first and second functions of sheet position. Sheet position for obtaining both desired motor velocities is determined by the pick system until a predetermined event. The feed-system sheet position is synchronized to the pick-system sheet position upon the happening of the event. Sheet position for obtaining both desired motor velocities is determined by the feed system after the event. Another method operates a printer pick motor and includes starting picking by driving the pick motor in a first direction, to move a sheet forward, with an input sufficient to prevent any teetering transitions between peaks and valleys of an encoder sensor output which would be falsely counted as forward motion by a single-channel encoder.

Abstract: A method is provided to reduce vertical banding defects in an ink jet printer. The method includes the steps of identifying a disturbance frequency of a disturbance source; identifying a natural frequency of a printhead carrier system; correlating the disturbance frequency of the disturbance source and the natural frequency of the printhead carrier system to a base carrier velocity; selecting a first carrier velocity for printing in a first direction, the first carrier velocity being different from the base carrier velocity; and selecting a second carrier velocity for printing in a second direction, the second carrier velocity being different from the base carrier velocity and different from the first carrier velocity.

Abstract: An encoder system may determine a plurality of intersection points for first and second encoder output signals produced by an encoder. Each intersection point may be determined by initiating a capture of sample points of each of the encoder signals and then examining the captured sample points.

Abstract: A printhead alignment sensor for an ink jet printer includes at least two terminals defining a gap therebetween. An electrical measuring device detects a change in an electrical parameter between two of the terminals when ink is in the gap between the at least two terminals.

Abstract: A method for rotating a printer paper-feed roller toward a desired rotational position wherein the printer paper-feed roller is driven by a motor. One step includes controlling the motor with a signal which at least includes the product of a scale factor and a function of an error signal, wherein the error signal represents the difference between the actual rotational position and the desired rotational position of the printer paper-feed roller. Another step includes varying the scale factor in a predetermined manner over time when a predetermined condition has been met. In one example, the scale factor is decreased in a linear manner over time when the predetermined condition has been met. In one implementation, the predetermined condition is a predetermined rotational distance of the printer paper-feed roller from the desired rotational position.