Xerox Corporation

Thomas J Hammond

James D Rees

William L Lama

Stephen C Corona

Karl A Northrup

Charles F Gallo, Jr

Fred F Hubble, Iii

James P Martin

George A Charnitski

Lawrence J Mason

Robert P Loce

Jeffrey J Folkins

Steven C Hart

Richard F Lehman

James M Casella

David K Shogren

Ronald E Jodoin

Eugene J Manno

Edward A Powers

James W Patterson

Dominick J Maiorano

Henry P Jankowski

Donald E Wiedrich

Charles F Sander

Winston J Powers

Mary F Krystofik

Thomas E Behrendt

A printbar assembly comprised of an array of light emitters, and array of gradient index lenses, and a light control film. The light control film, which is comprised of a plurality of microlouvers, is disposed such that it limits the angle at which light from the light emitters can enter the gradient index lenses. The light control film increases the depth of focus of the gradient index lens array without significantly reducing the effective radiometric efficiency.

LED printbars with depth of focus enhancement

A light emitting diode based exposure station (and electrophotographic marking machines that use such exposure stations) that requires only a small amount of photoreceptor waterfront (space). The small waterfront requirement is achieved using a gradient index lens array that transmits focused light onto the photoreceptor with a total conjugate that is sufficient to permit the widest part of the light emitting diode based exposure station to be displaced sufficiently far from the photoreceptor that other printing machine devices can be disposed between the widest part of the exposure station and the photoreceptor. The increased total conjugate is achieved using a gradient index lens array having longer rods and/or wider rods.

Electrophotographic marking using an exposure station having a small waterfront requirement

Arrays of light emitting diodes, and LED printbars and electrophotographic marking machines that use arrays of light emitting diode, that have active area geometries that produce compact irradiance profiles. Compact irradiance profiles are achieved by placing the diode electrodes along the outer periphery of the light emitting active areas. When used with gradient index lenses, such light emitting diodes produce light spots having more compact irradiance profiles. When such light emitting diodes and gradient index lenses are incorporated into LED printbars, and when those printbars are used in expose stations of electrophotographic marking machines, improved composite images can result.

High resolution printbar pixel geometries

An imaging module mounting structure is used for mounting an imaging module to an imaging device that has a support member and a rotatable photoreceptor. The imaging module includes an imaging bar and a corona generating device. The imaging module mounting structure includes a pair of pivot block devices which are pivotably connected to the support member in a spaced apart relationship. The imaging bar and the corona generating device are secured to each one of the pair of pivot block devices. Each pivot block device includes a cam follower element. The pair of pivot block devices are operative to flex independently of one another while the photoreceptor rotates so that the respective cam follower elements remain in contact with the rotating photoreceptor to compensate for photoreceptor run out. A method for practicing the present invention is also described.

Imaging module mounting structure

An apparatus for compensating LED printbars, and printers which use LED printbars, for aging. Changes in the slopes of the forward voltage drop verses forward current characteristics (the I-V characteristics) of the LEDs of the LED printbar are determined. The drive currents of the LEDs are then changed as a function of the changes in the slopes so as to compensate for changes in the LED light outputs.

LED printbar aging compensation using I-V slope characteristics

Uniformity light output of an LED printbar is achieved by a technique which senses the operational on time of each LED. When the on time difference between the LED with the longest on time and the LED with the shortest on time exceeds a predetermined value, the outputs of at least some LEDs comprising the printbar are compensated for to normalize their light output. This normalization is achieved via a drive circuit which drives each LED based upon correction data, and by determining an update of the correction data based upon the difference between the on time of individual LEDs. The correction data is determined when the difference between the on time of the LED with the longest on time and the on time of the LED with the shortest on time exceeds a predetermined maximum difference.

Automatic LED printbar uniformity and adjustment

An apparatus for positional tracking a moving photoconductive belt and adjusting an imager in an electrophotographic printing machine to correct for alignment errors when forming a composite image. Registration errors are sensed by developing an appropriate set of target marks, detecting the target marks, and controlling the position of the imager.

Apparatus for image registration

A precision belt hole sensor and associated conditioning circuitry provides precise trigger signals that enable synchronous printing in a color printer. An image bar recording system, which, in a preferred embodiment, utilizes a plurality of LED image bars, forms a plurality of latent images on a moving photoreceptor which may subsequently be developed in different colors. A pair of sensors associated with each printbar views illuminated pixels at the end of a printbar, through a pair of oppositely aligned photoreceptor holes. The signals detected by the sensor are amplified and processed to provide inputs to a comparitor circuit which generates an output signal at a time which precisely defines the passage of the trailing edge of the hole, past the sensors. The signal from the comparitor is used to accomplish skew registration of the printbar and to provide sync signals to enable precise formation of the leading edge of the associated image frame.

Method and apparatus for registration of sequential images in a single

A single pass, hybrid ROS/print bar system provides a plurality of latent images which may subsequently be developed in different colors. A ROS unit is initially aligned so that each scan line is registered in the process direction. The alignment is accomplished by forming a pair of opposed V-shaped apertures in the surface of the belt and detecting scan line cross-over of the legs of the V. These cross-overs are manifested as two sets of pulses generated by sensors associated with each target leg. The time differences between pulse sets are compared and the scan line is rotated until the time differences are equal. Once the ROS is registered for skew, one or more print bars are registered by enabling non-image pixels and comparing the output generated by detectors when the lit pixels are viewed through the V-shaped aperture.

The present invention relates to a color printer which forms multiple latent images on the surface of a belt type photoreceptor in a single pass. The invention enables the placement of imaging stations on both a tensioned and non-tensioned side of the belt. On the non-tensioned, an asynchronous line at a time printer such as an LED print bar is used to form the latent image in response to video data signals. On the tensioned side of the belt, either synchronous type imagers, such as laser ROSs or asynchronous imagers such as LED print bars may be located to form the latent image. The leading edges of each image frame are registered according to known methods. Each scan line within an image frame is registered by comparing the belt speed beneath each of the imagers and generating a correction signal to the asynchronous print bar. Since the print bar operates asynchronously, it is possible to vary the pulsed line write time so as to register each of the scan lines formed by the print bar with the scan line being formed by the imagers at the tensioned side of the belt.

Color printer

A printing system operating in a charged area development environmental utilizes a high resolution image print bar in cooperation with a low resolution image discharge bar to expose a charged surface of a photoreceptor with a minimum of stress being applied to the high resolution bar. The high resolution bar is addressed from an image data source so as to expose areas of the photoreceptor which correspond to informational areas of the image being printed. The low resolution bar is addressed from the same data source so as to discharge the photoreceptor surface in non-informational areas such as background areas and interimage areas. In a preferred embodiment, both the high and the low resolution bars are LED arrays located in a common exposure station.

Method and apparatus for charged area development printing with high and

An amalgam fluorescent lamp is designed to operate with minimum axial illumination variations when changing from an off to an on state. This is accomplished by incorporating at least three amalgam patches internal to the lamp. Two patches are located at opposite ends of the lamp, and at least a third patch is centrally located. Each patch has an associated thermistor ands external heater sleeve. The patch temperature which correlates wiht the optimum lamp operating temperature is continuously monitored and adjustments are made to the heater sleeve elements to maintain the patches at desired optimum temperature.

Temperature control of a fluorescent lamp having a central and two end

An exposure control system for a document copier is enabled by positioning a segmented variable reflectance mirror along the optical imaging path. The mirror segments incorporate a material whose transmission changes in response to applied voltage signals, the preferred material being an electrochromic material. In a first embodiment a white reference strip along the platen surface is exposed and the charge levels along discrete areas of the photoreceptor are measured by an electrometer with a plurality of probe segments. Outputs from each probe segment are processed in a control circuit and a signal sent to an appropriate mirror segment to increase or decrease reflectance to enable a corresponding decrease or increase, respectively, of the charge level, at the corresponding discrete areas of the photoreceptor illuminated by the mirror segments.

Exposure control system

Flash lamp intensity control in which a small preflash lamp first exposes each document on the platen of an electrostatographic machine, a photosensor generates a signal representative of the intensity of the light reflected from the platen, and a controller increases power to the main flash exposure lamps in response to the signal where the measured intensity is less than the normal exposure intensity of the main flash lamps.

Flash lamp intensity control for electrostatographic reproduction

Lamp operating voltage levels are reduced by using a boost circuit to initiate a triggering sequence in one of two lamps connected in series. The boost circuit is connected across one of the lamps at a connector point common to the two lamps. In a preferred embodiment, trigger pulses are applied sequentially to each lamp, the boost circuit voltage contained in an associated capacitor is discharged through the first triggered lamp, causing it to begin conduction. Most of the voltage from a main storage capacitor then becomes available to break down the second lamp.

Growing community of inventors

Penfield, NY, United States of America

Thomas J Hammond