Abstract: Disclosed are methods for compensating for failed ink jets in an ink jet apparatus. The method in embodiments determines if one or more ink jets are nonfunctioning or have failed and substitutes for the one or more nonfunctioning ink jets by using one or more operational ink jets. The operational ink jets used are neighboring operational ink jets that fill in for the one or more failed ink jets. The one or more failed ink jets are disabled wherein a primary image pass is performed followed by one or more additional imaging passes to fill in for the one or more disabled ink jets by enabling the one or more neighboring operational ink jets. The additional imaging passes may be a right fill imaging pass, a left fill imaging pass or a combination of both.

Abstract: An image transfer ink-jet printer employs an image receiving drum that rotates relative to an ink-jet array print head spanning the full width of the drum. A print head positioner moves the print head in precise increments to position adjacent scan lines of ink drops. Without affecting the overall scale of the image, adjacent pairs of scan lines are spaced at distances less than one nominal pixel width. Pairings within the range of 0.2 to 0.5 pixel widths are used, with optimal spacing at 0.35 pixel widths.

Abstract: A voltage mode drive for a servo system builds a drive matrix from an error signal, which is the difference between a measured value for a parameter of the servo system, such as the position of a rotating drum, and a reference signal, a voltage control signal for the servo system, and an estimated set of parameters for the servo system, the parameters including drive current. The outputs from the drive matrix are a new estimated set of parameters for the servo system which are multiplied by appropriate system constants to produce the voltage control signal. The voltage control signal is amplified by a voltage amplifier and applied to drive the servo system.

Abstract: A print head (216) positioner (260) includes a stepper motor (264) that is coupled by a substantially friction- and backlash-free taut metal band (266) to a lever arm (268) that imparts precise lateral motion to a positioning shaft (220) that is rigidly attached to the print head assembly. Each step of the stepper motor is translated by the lever arm into one pixel (0.085 millimeter) of lateral movement of the shaft. The exact amount of translation per step of the stepper motor is adjustable by an eccentrically mounted ball (272) that is minutely positionable (274) on the lever arm. The ball couples angular motion of the lever arm to lateral motion of the shaft such that adjusting the ball position on the lever arm provides a-variable scale factor adjustment that compensates for tolerance buildups and exact inter-nozzle spacing on the print head. The shaft is biased toward the ball by a spring (284).

Abstract: A printer accurately controls the passage of print media therethrough and maintains the print media taut as the print media passes through a printing zone while the media is printed by an ink jet printer. The print media sheet is preferably carried by a rotating drum in a first direction through the printing zone, with the drum being reversed to cause the exiting of the print media sheet from the printer. A pressure fixing or fusing apparatus may be positioned to flatten ink spots on the print media as the print media exits from the printer. The pressure fixing or fusing mechanism is preferably used in the case of a hot-melt or phase-change ink jet printer.

Abstract: A cylindrical drum is rotatable about a drum axis for supporting a print medium during printing. A print head has a plurality of printing elements for printing image elements of a predetermined color at a predetermined image-element printing rate. The drum is rotated about the drum axis at a predetermined speed such that alternate image-element locations are addressed by each printing element during each rotation of the drum at the predetermined printing rate. The drum rotates two revolutions at each print-head location along the axis, and all image-element locations are addressed.

Abstract: The present invention provides a stable, high performance system for driving one or more masses in precise incremental movements. More particularly, the present invention provides a method and system for deriving and implementing motion profiles that govern the movement of one or more masses, such as a printer drum as it is indexed along a rotational path by a stepper motor.

Abstract: Methods and apparatus for processing printed substrates having a phase change ink layer of non-uniform thickness are disclosed. Application of a combination of heat and pressure reorients the printed ink layer to provide a layer having a substantially uniform thickness and flat surface conformation, at least in the area of each discrete color. A release surface (55) is positioned adjacent the printed ink layer during processing. A resilient contact surface (56) is also provided to facilitate reorientation of the printed ink layer. Mechanical buffing of the processed, printed substrate improves image quality. Application of a light transmissive, protective coating that overlays the printed ink layer also improves image quality.

Abstract: A compact ink jet printer is described utilizing a small drum for carrying a sheet of record medium during the printing operation. In one embodiment, the drum has an exterior surface with a high coefficient of friction with a contact roller retaining the record medium against the drum as the drum is rotated. Printing is accomplished as by jetting ink from an ink jet print head onto the medium while the medium is backed up by a fixed platen. A fusing mechanism may be utilized to flatten ink drops on the printed medium. A drive mechanism for an ink jet printer may include a stepper motor coupled by timing belt sprockets and a timing belt to the drum of the printer. These components may be selected such that the drum is incremented a multiple of a pixel height during each step of the stepper motor. The record medium may also be clamped to a drum by a clamping mechanism and rotated through plural revolutions of the drum during respective printing and fusing steps.

Abstract: A system (11) for monitoring and controlling the movement of a mass (12) along a predetermined path (14) by a motor-driven flexible member (20) is provided to modulate the motor drive output so that the actual velocity of the mass corresponds more closely to the desired target velocity profile. The system preferably employs a dual loop servo system wherein an outer servo loop uses conventional linear encoding techniques and is supplemented by an inner servo loop utilizing a sensor (27) that detects a physical characteristic of the flexible member representative of the relative velocity of the mass. Relative velocity transducers utilizing magnetic circuits and operating according to variable reluctance principles for generating relative mass velocity signals directly are disclosed.

Abstract: An apparatus providing a substantially fixed length cable drive comprises a motor-driven capstan having a helical groove. The groove on the capstan is sized to receive opposite ends of a cable for simultaneously letting out and taking up the cable. The cable passes over a fixed pulley and is attached to a carriage at a point intermediate the capstan and pulley. The carriage is guided along a rail defining a fixed mass path. The section of cable between the carriage and pulley is parallel to the mass path. The cable ends on the capstan are disposed on opposite sides of a plane containing the parallel cable section during travel of the carriage along the mass path.

Abstract: A motion controller for the head carriage of an ink jet printer comprises a target signal generator providing constant velocity reference input to a servo loop controller. Also, two levels of current are applied to the drive motor during direction reversal, a lower one during deceleration of the carriage, and a higher one during acceleration of the carriage. The timing of the two current levels is determined by inputting a rectified velocity signal into a slope detector. A comparator converts the output of the slope detector into a binary signal for controlling the motor current level.

Abstract: A control topology for a servo motor carriage drive includes a strain gauge coupling the carriage to a motor-driven belt to provide a signal representative of the flexure of the belt. A velocity signal is taken from a linear encoder on the carriage. These signals are used in inner and outer feedback loops for controlling the velocity of the carriage as it travels along a predetermined path.

Abstract: An add-on alarm system for use in conjunction with an audio detector. The system includes an indoor unit that is audibly coupled to the detector and an outdoor unit containing an independent power supply that communicates with the indoor unit to provide an alert signal for directing rescue operations. The outdoor unit includes a relay which is energized by a signal from the indoor unit to close a contact in an alarm circuit and thus generate an alert signal. The relay is held energized by the outdoor power supply so that the alert signal persists in the event the detector or the indoor unit becomes disabled.

Abstract: A device for reciprocally rotating an output element such as a scanning mirror by means of an electric motor employs a two-degree-of-freedom suspension in which the motor armature is constrained by a first torsional suspension and the output element is supported from the armature by an independent second suspension. The resonant frequency of the armature and its suspension is substantially equal to the resonant frequency of the output element and its suspension.

Abstract: A velocity-compensation circuit for a limited-displacement motor comprises a bridge circuit incorporating the control winding of the motor in a first arm. An adjacent bridge arm includes both an inductance and a resistance whose ratio is the same as that of the first bridge arm. The bridge is balanced to eliminate from its output the effect of current through the control winding. The bridge output in normal operation is therefore solely a function of motor velocity and this signal is fed back to provide velocity compensation for the motor.

Abstract: A vibration damper for a transducer positioning system of a diskette system employing a stepping motor for driving a moveable transducer carriage that is coupled to the stepping motor drive means. The mass of the carriage and the coupling means form a vibratory system having a natural frequency of oscillation significantly different from the frequency of the pulses applied to the stepping motor so that while the motion of the carriage reflects the total motion of the shaft, the incremental motions of the shaft are not transmitted to the carriage thereby minimizing noise ancillary to the positioning of the carriage.

Abstract: An optical scanner capable of scanning parallel to two intersecting axes. The scanner comprises a single electromechanical transducer and a compliant link interconnecting the transducer with an optical element to which the two-axis movement is to be imparted. The link is selectively compliant to two planes containing the two axes and it is oriented to receive from the transducer force components in both planes. The transducer is driven at the frequencies of the resonances associated with the link compliances and the masses involved therewith. The link thereby imparts amplified motion to the optical element simultaneously in both planes, the resulting path described by the element thus being a Lisssajous pattern.

Abstract: Apparatus for moving a transducer carriage intermittently along a tract relative to a recording medium employs belting arranged in a closed loop that is tensioned by engagement around at least one idler and connected to the carriage. Belt end segments comprising the loop are wrapped in opposite directions around the periphery of a stepping motor-driven capstan and their ends are secured thereto at axially spaced apart locations thereon. The belting and idlers are arranged so that all of the belt segments wrapped around the capstan remain parallel to the carriage track as the capstan rotates so as to advance the carriage a maximum number of increments along its track.

Abstract: The armature of a limited-rotation motor which rotates about an axis relative to a stator is extended axially beyond the stator between arcuate, non-magnetic capacitor plates disposed in a cylindrical array coaxial with the rotation axis. The capacitor plates are connected in a bridge circuit whose output is a selected function of armature displacement. The capacitor plates are installed at the end of the motor stator during assembly of the motor as tines of a unitary slotted bushing that is reamed simultaneously with the motor stator, following which the bushing is circumferentially cut to electrically isolate the bushing tines to form the individual plates.