Abstract: An electromagnetic shutter (40) is comprised of two poles, a south pole (42) and a north pole (44) that are disposed above the surface of a delivery roller element (32). The delivery roller element (32) rotates about a fixed magnet (30) that has various poles. The south pole (42) of the electromagnetic shutter (40) is aligned proximate to the one of the north poles of the magnet (30). When the electromagnetic shutter (40) is activated with the windings (48) and (50) or winding (48) only, the shutter will form a magnetic dam (79) of toner particles which will effectively prevent passage of the toner particles thereby.

Abstract: A buried electrode drum (48) includes a rigid core (10) over which a controlled durometer layer (12) is disposed. On the surface of the controlled durometer layer (12) is disposed a buried electrode layer (14), having electrodes (16) disposed therein along the longitudinal axis of the drum (48). The electrode layer (14) is covered by a controlled resistivity layer (18). The controlled resistivity layer (18) is operable to be contacted on the surface thereof by an electrode (24) to allow a voltage to be transferred to the underlying electrodes (16) and therefrom along the longitudinal axis of the drum (48). Various electrodes can be disposed about the peripheral edge of the drum (48) to allow any pattern to be formed on the surface of the drum (48).

Abstract: A precurl device for adjusting the curvature of the paper prior to being disposed on a transfer drum (48). The paper is fed along a path defined by a guide (296) to a nip between two precurl rollers (244) and (246). The durometer of the roller (246) is higher than the durometer of the roller (244), such that the roller (244) will deform at the nip between the rollers. The paper is fed to an attachment roller (198) that is adjacent the drum (48). A variable precurl device (312) is operable to vary the force on the roller (244) against the roller (246), to vary the amount of arcuate deformation imparted to the paper (146).

Abstract: An electrophotographic print engine includes a photoconductor drum (20) that interfaces with a transfer drum (48) to form a transfer nip therebetween. Paper is disposed in a paper feed path (242) for traversal through the nip between two precurl rollers (242) and (244). The durometers of the two rollers (242) and (244) are different, such that one roller will cause the other to compress. This causes the paper to have a curvature bias in the direction of the curvature of the drum (48). The paper is then fed into an attachment nip formed between an attachment roller (198) and the drum (48). The paper is adhered thereto by electrostatic forces with the curvature of the paper allowing smaller forces to be utilized. In a multi-color print operation, the paper is maintained on the drum (48) for a number of passes until all images have been transferred thereto from the drum (20). A picker (248) then extracts the paper from the drum (48) and feeds it into a fuser mechanism.

Abstract: A buried electrode drum (48) includes a rigid core (10) over which a controlled durometer layer (12) is disposed. On the surface of the controlled durometer layer (12) is disposed a buried electrode layer (14), having electrodes (16) disposed therein along the longitudinal axis of the drum (48). The electrode layer (14) is covered by a controlled resistivity layer (18). The controlled resistivity layer (18) is operable to be contacted on the surface thereof by an electrode (24) to allow a voltage to be transferred to the underlying electrodes (16) and therefrom along the longitudinal axis of the drum (48). Various electrodes can be disposed about the peripheral edge of the drum (48) to allow any pattern to be formed on the surface of the drum (48).

Abstract: A method for measuring and adjusting the toner density of black toner in a multi-color copy machine includes first developing and transferring a layer of yellow toner (132) onto the surface of a transfer belt (18). A crosshatch pattern (134) of black toner is then developed and transferred onto the surface of the yellow toner layer (132) in a series of patches (138)-(148). The cross-hatch pattern (134) is comprised of vertical and horizontal bars (136) that are spaced a predetermined distance apart and have a predetermined width. A toner density sensor (40) is disposed over the surface of the transfer belt (18) to measure the toner density. The amount of toner deposited on a photoreceptor belt (12) is altered by varying the grid voltage on a charging corona (28) during the developing step to provide multiple toner densities for each of multiple patches (138)-(148). This data is then extrapolated to determine what the grid voltage on the charging corona (28) should be for the desired toner density.

Abstract: A belt conditioning system for a flexible belt electrophotographic print engine includes a cleaning blade (144) which is operable to clean a transfer belt (20) on a per page basis. A roller (152) is operable to be disposed in contact with the belt (20) on a page intermittent basis to more aggressively condition the belt (20). A controller (39) is operable to activate the roller (152) on a page intermittent basis and, during activation of the roller (152), transfer of images to the transfer belt (20) from a PC belt (30) is inhibited to prevent any registration problems from occurring during the conditioning cycle.

Abstract: A transfer mechanism for a full color double transfer electrophotographic print engine. Relatively conductive developer materials having successively increasing triboelectric charge characteristics are used to develop sequential images. Conductive plates displaced away from the transfer station along the direction of travel of the transfer belt are used as one electrode for applying an electrostatic field at each transfer station. A parameter of the transfer mechanism is a bulk resistivity of the transfer belt in the range of 10.sup.7 to 10.sup.10 ohm-centimeters and a surface resistivity for the belt in the range of 10.sup.7 to 10.sup.10 ohms per square. A selectively operable compression roller, compressing paper and transfer belt against a rubberized idling roller at one of the transfer stations increase dwell time in the transfer station. The compression roller automatically falls to a cleaning station where it is rotated by another rotary member to clean it between transfers.

Abstract: An audio conferencing system includes a plurality of remote stations (10) which are interconnected in a conference mode through a central switching network (66) through communication lines (16). Each of the remote stations has a microphone (34) and a speaker (64) associated therewith. The microphone (34) on each of the remote stations has a voltage controlled amplifier (VCA) (59) associated therewith and the speaker (64) has a VCA (60) associated therewith. A CPU (48) selectively controls the output of the microphone (34) to selectively decrease the gain thereof when voice is not detected. When voice is detected above a predetermined threshold, the microphone (34) is allowed to operate at full gain and the speaker (64) has the output level thereof decreased. This effectively reduces the audio loop gain between remote stations in a conference.

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).