A system for writing geometric structures on a photosensitive substrate including a modulated laser beam source, a focusing lens, a deflector for producing a scanning action between the light source and the lens, and a device for mechanically moving the surface relative to the laser beam. Compressed data for use in writing the geometric structures is read out of a memory into a data delivery circuit such that the data is formatted to have both beam power and position information. A modulator logic circuit operates to call up the data from the data delivery circuit, form a modulation drive signal based on the power information, and delay the modulation drive signal based the position data. The modulator logic circuit thus operates to vary the modulation drive signal to begin or end exposure along the scan lines with greater resolution or pixel density by at least a factor of four more than the resolution or spacing density between adjacent scan lines. The scan lines are arranged within stripes, and adjacent stripes preferably are made to overlap such that the stripes are blended in the overlap according to a predetermined stepwise changing function.

Method and apparatus for the production of a structure by focused laser radiation on a photosensitively coated substrate

An image forming apparatus such as a laser beam printer or an ink-jet recording apparatus has a recording head which records an image on a recording medium in the direction of main scan in accordance with image signals. The recoding medium is moved relative to the recording head in a sub-scan direction substantially perpendicular to the direction of the main scan. A controller controls conditions of recording performed by the recording head so as to effect a correction of recording density unevenness cause by a variation of the relative speed of movements of parts of the apparatus.

Image forming apparatus with means for correcting image density unevenness

In a copier or printer producing a sequential stream of sheets with limited time therebetween, and with compiling and finishing of those output sheets on-line while subsequent sheets are being printed, a non-slip sheet feeder normally feeding copy sheets downstream to the compiler is selectably intermittently temporarily stopped holding the lead edge area of the first copy sheet for the next set to be finished so that continued feeding of the trail end of the same sheet by a relatively closely spaced upstream feeder buckles that sheet into a buckle chamber assisted by a buckle inducing arcuate baffle extending from the other side of the sheet path. The next printed sheet is fed normally while the buckled first sheet is positively held out of its way. When the second sheet reaches the downstream feeder, it restarts to positively feed both sheets downstream to the compiler, together, but overlapped by a preset amount for registration stacking. A substantial increase is provided in the time for the preceding copy sheets to be operated on in the compiler. A plural sheet collection point may also be provided by this sheet buffering system.

Trail edge buckling sheet buffering system

A large scale LED exposure array and system for printers, and unique methods of inputting data to and operating such an array, are disclosed. The array can be loaded and refreshed with data information at rates compatible with high speed printing, and forms part of an electronic image forming and handling system which can load an refresh an exposure array at variable speeds of at least 100 to 300 ft./min. The system includes compensation for differences in illuminating capability of individual LEDs in a large array, by introducing modifications in LED on-time which are centered with respect to the incremental area of the photoreceptor on which a pixel is to be formed, and to compensate for changes in pixel exposure time with increase in speed of the photoreceptor. Also disclosed are an LED configuration which can emit high energy in a controlled pattern to give a desired pixel spot on a photoreceptor, and an arrangement for mounting the array to maintain each light emitting spot in focus on the photoreceptor surface, although a wide array is employed.

Imaging diode array and system

The present invention is a method and apparatus for compensating for position error inherent in a raster output scanning printing system by adjusting the intensity of image exposure to effect a correction in the output image. The invention is particularly well suited to compensate for position errors arising from a plurality of sources by first summing the errors and then applying a single compensating adjustment to the intensity of individual scan rasters based upon the position error thereof.

Method and apparatus for compensating for raster position errors in output scanners

A photosensitive, photoconductive media moving in a first direction relative to a laser light beam scanning in a second direction, transverse to the first direction, incurs velocity variations. These velocity variations result in variations in the absolute and relative heights of white and black image features. This printed image nonuniformity is especially visually detectable for closely spaced parallel lines in the second direction, and/or gray scale. An optical velocity sensor senses instantaneous media velocity. An analog or digital velocity error processor maintains a running average velocity and determines, by subtraction, an instantaneous velocity error as the difference between currently sensed and running average velocities. The instantaneous velocity error so determined is used to adjust the intensity of the laser light beam to be proportionally brighter (dimmer), exposing a wider (narrower) scan line, on a faster-moving (slower-moving) media region. By this compensating, the ratio of white and black image features is maintained constant during media velocity variations.

James A. Howe

Papers

Modulating laser intensity in a laser printer proportionately to the velocity of the photoconductive media