Abstract: An electrophotographic print engine with a photosensitive flexible belt stretched over a plurality of rollers in a compact electrophotographic printer such that a developing position on the belt is disposed in a vertical plane, the developing position exposed first to a light on one side of the printer and activated to trace the image of the document to be printed and second passed vertically adjacent at least one toner module extending a decorator roller horizontally to the photosensitive belt on a second side of the printer to create a developed image, the developed image transferred at the upper end of the vertically disposed belt to the downward facing side of a sheet of paper which passes through a fuser to fix the print before the paper is placed facedown in an output tray, permitting the compact printer to create multi-page documents in sequence without manual re-sorting of the document, residual toner wiped from the vertically disposed belt to fall by gravity to a modular collection receptical.

Abstract: An improved toner module for use in an electrophotographic print engine. A decorator or developer roller with a rotatable core provides an apparatus for, and an improved method of, replacing developer. The decorator roller has a core that is partially magnetic and partially nonmagnetic. By rotating the decorator core to adjust the position of the non-magnetic portion of the decorator core, developer can be both removed and added without the use of any additional equipment. A mixing roller within the toner module provides for greater quantity of developer to be stored within the toner module. The disclosed toner module therefore has a greater capacity for storage of developer.

Abstract: An improved color correction apparatus for improved color printing in a subtractive color printing system is disclosed. The disclosed apparatus utilizes an optimized three-dimensional look up table of pigment density values addressed by primary color values. The look up table is created by printing a plurality of pigment bars in response to known input density signals to a laser beam for each of three color pigments used in the system. Each of these sets of bars is subsequently scanned by the input scanner to determine the spectral content of the resultant bars and thus create a plurality of color pigment values corresponding to the spectral content of each bar for each color which is a complementary color of one of the pigments. These characteristics are used to calculate the spectral content of an actual printed image generated in response to an image generated by an input triplet to the system.

Abstract: Improved dual belt synchronization for a print engine for color electrophotography using a photoreceptor belt and a seamless transfer belt on which a composite image is built up. Improved synchronization of the two belt drives enhances image registration. A tension mechanism used in conjunction with the belts prevents rapid changes in the belt dimensions. An improved transfer belt cleaner system is synchronized with the belt drives such that excess toner is not left in the imaging area of the transfer belt.

Abstract: A video conferencing network includes remote video terminals (10) interconnected to a switching network (66) through coaxial cables (16). The switching network (66) is operable to provide an audio and video data path between two or more video terminals (10). The switching network (66) operates as both an audio/video crosspoint switch and also as a network controller. In the network control mode, the switching network (66) operates in both a master mode for maintaining data communication with all of the video terminals (10) and also in a slave mode for maintaining status of devices attached to the switching network (66). In the master mode, the switching network (66) receives requests from each of the video terminals (10) and services these requests to determine available data paths for interconnection with other video terminals. In the slave mode, the switch (66) is in data communication with all of the video terminals (10) to determine the status thereof which is stored in a slave status table.

Abstract: A workstation (10) for interfacing with a video conferencing network comprises a display (12) which has an internal camera (32) associated therewith. The camera (32) and various auxiliary devices such as a VCR (28) are input to a video switch (52) for selecting a video output. The video output is input to either a monitor (12) and/or to the network through an interface circuit (51). In addition, video can be received from a local processor (42). The monitor (12) operates at two video rates and can be switched therebetween by a CPU (48). The local processor (42) operates at a separate rate from the NTSC video of the monitor (12). A viewfinder (14) having a viewing surface smaller than the monitor (12) is provided as another output on the video switch (52) such that two displays can be received by the user at a given time. A microphone (34) and a speaker (64) are provided and controlled by an audio switch (54 ). This allows a full duplex audio path to exist between the network and the workstation (10).

Abstract: An adaptive system is shown for electronically correcting for errors in a laser scanner. A start-of-scan signal is provided by a photodetector having a special mask with a window over the front of the photodetector. The start-of-scan signal from the photodetector eliminates the facet-to-facet errors. The special mask gives a stepped amplitude signal output from the photodetector with the maximum amplitude of the signal providing amplitude modulation to correct the intensity of the laser beam, and the lower amplitude of the stepped amplitude signal providing frequency modulation to correct the facet-to-axis error. By the use of the delays, counters, and memory, the intensity and facet-to-axis errors are continuously being corrected with each revolution of the spinner.