Abstract: A cleaning blade having a dual action cleaning blade. One side of the cleaning blade is coated with an abrasive material. The cleaning blade is used in an electrophotographic printing machine to remove residual particles from a photoconductive surface.

Abstract: A printing machine having a pair of photoconductive drums with a transfer roller interposed therebetween produces a full color document in two operating cycles. During the first operating cycle, a first color developed image is transferred from the first photoconductive drum to a sheet moving with the transfer roller. A second color developed image is transferred from the second photoconductive drum to the sheet in superimposed registration with the first developed image transferred thereto. During the second operating cycle, the foregoing process is repeated for a third color developed image and a fourth color developed image. In this way, a full color composite toner image is formed on the sheet.

Abstract: A developer unit which develops an electrostatic latent image recorded on a photoconductive member used in an electrophotographic printing machine. The developer unit uses a developer material which ages during the life of the electrophotographic printing machine. Additional developer material having at least carrier granules and toner particles, is supplied to the developer material in the developer unit to extend the life of the developer material. Discharge of developer material from the developer unit is controlled by a permanent magnet and an electromagnet positioned adjacent an exit port in the developer unit. The permanent magnet generates a magnetic flux field in the region of the exit port to form a developer material curtain which prevents the passage of developer material from the exit port. When the electromagnet is energized, it generates a magnetic flux field which attracts developer material from the developer material curtain.

Abstract: An electrophotographic printing machine in which a color highlighted original document having black indicia and non-black indicia thereon is reproduced in a single cycle. An optical system exposes the charged portion of the photoconductive member to record an optical electrostatic latent image corresponding to the black indicia of the original document. The optical electrostatic latent image is developed with black marking particles. Thereafter, the photoconductive member is recharged and a raster exposure system exposes the charged portion of the photoconductive member to record a raster electrostatic latent image corresponding to the non-black indicia of the original document. The raster electrostatic latent image is then developed with non-black marking particles. The black and non-black marking particles are transferred to a copy sheet and permanently fused thereto forming a highlight color copy of the original document.

Abstract: An apparatus in which successive developer units are moved to a development zone to develop, with different color toner, successive latent images recorded on a photoconductive member. At least four developer units move in unison with one another to index successive developer units into the development zone. The developer units translate horizontally to develop successive latent images. The first developer unit, third developer, fourth developer unit and second developer unit are indexed sequentially into the development zone to develop the first, second, third, and fourth latent images, respectively.

Abstract: An infrared densitometer which measures the reflectivity of a selected region on a moving photoconductive belt covered at least partially with marking particles. Collimated light rays are projected onto the selected region of the moving photoconductive member with or without marking particles thereon. The light rays reflected from the selected region of the moving photoconductive member are collected and directed onto a photodiode array. A photodiode array generates electrical signals proportional to the diffuse component of the total reflectivity of the selected region of the photoconductive member with and without marking particles thereon. Circuitry determines a control signal as a function of the difference in electrical signals.

Abstract: A developer unit which stores a supply of developer material has a capacitance cell positioned therein contacting the developer material. The capacitance cell measures the change in capacitance of the developer material and generates a signal indicative thereof. The capacitance change is caused by a change in the dielectric characteristics of the developer material due to changes in the moisture content thereof. This signal, in combination with a signal indicating the concentration of toner particles in the developer material, is used to control various processing stations in the printing machine employing the developer unit.

Abstract: An apparatus in which a sheet is advanced into registration with different color information developed on master sheets secured releasably on different drums. Each master sheet is secured to a gripper bar having outwardly extending pins. The pins in the master sheet gripper bars mount in holes in the drum and extend outwardly therefrom. A chain driven gripper bar advances the sheet into registration with successive master sheets. The sheet gripper bar is mounted pivotably and slidably on the chain. The sheet gripper bar has notches in the leading edge thereof to mesh with the pins extending from the master sheet gripper bar. This detachably couples the sheet and the master sheet to move in unison with one another. In this way, the sheet is placed in registration with the different color information developed on each master sheet.

Abstract: An apparatus in which successive toner images are transferred from a photoconductive drum to a sheet at a transfer zone. The sheet is transported by a perforated belt entrained about a stationary sleeve through a recirculating path. The sleeve has a plurality of spaced ports extending in and through the periphery thereof and connected to a vacuum source. In this way, the sheet is vacuum tacked to the belt to move in unison therewith in synchronism with the photoconductive drum. At the transfer zone, the sheet separates the belt and is interposed between the photoconductive member and a corona generator. The corona generator applies an electrostatic charge to the sheet to attract successive toner images thereto. The sheet moves with the belt in a recirculating path so that successive different color toner images are transferred thereto in registration with one another.

Abstract: A web-steering mechanism, particularly for the endless belt of a xerographic copier, uses two rolls to hold the belt under tension. An idler roll is designed to rotate about an axis which is at a small angle to a tilt axis of the idler roll assembly. Small tilting movements of the idler roll assembly, under the control of a servo-motor are effective to alter the angle at which the web enters and/or leaves the roll, to cause the web to walk along the tilted roll.

Abstract: An electrophotographic printing machine in which an electrostatic latent image is recorded on a photoconductive surface. One portion of the latent image is a discharged area with the other portion of the latent image being a charged area. The discharged image area is developed with toner particles of a first color and polarity by a first developer unit. No greater than 2% by volume of these toner particles have a diameter greater than about 20 microns. The first developer unit generates a weak magnetic field in the development zone and a strong magnetic field at the entrance and exit of the development zone. A second developer unit develops the charged image area with toner of a second color and polarity. The colors of the toners are different from one another.

Abstract: An apparatus in which a latent image is developed with magnetic developer material. A rotating applicator roll transports the developer material. A magnet is mounted rotatably interiorly of the applicator roll and generates a magnetic flux field which attracts the developer material to a portion of the surface of the applicator roll. The magnet rotates under the influence of the magnetic flux field force applied thereon. When the apparatus is developing the latent image, the magnet is prevented from rotating in a first position wherein the magnetic flux field attracts the developer material to the portion of the applicator roll adjacent the latent image. Conversely, when the apparatus is not developing the latent image, the magnet is prevented from rotating in a second position wherein the magnetic flux field attracts the developer material to the portion of the applicator roll spaced from the latent image.

Abstract: A densitometer which measures the reduction in the specular component of the reflectivity of a portion of a surface having a liquid deposited thereon. Collimated light rays, in the visible spectrum, are projected onto the portion of the surface having the liquid thereon. The light rays reflected from the portion of the surface having the liquid deposited thereon are collected and directed onto a photodiode array. The photodiode array generates electrical signals proportional to the total flux and the diffuse component of the total flux of the reflected light rays. Circuitry compares the electrical signals and determines the difference therebetween to generate an electrical signal proportional to the specular component of the total flux of the reflected light rays.

Abstract: An apparatus which develops an electrostatic latent image recorded on a photoconductive member with toner. The toner in the chamber of the developer housing is fluidized and transported thereacross by an elongated member. A donor roller advances the toner particles to a latent image recorded on a photoconductive member. A rotating rod resiliently urged into contact with the donor roller charges the toner on the donor roller. In order to attract toner particles to the donor roller, the elongated member and the charging rod are electrically biased by voltages having the same polarity. The elongated member and the charging rod are electrically biased by voltages of opposite polarity to denude the donor roller of toner particles.

Abstract: An apparatus which develops an electrostatic latent image. A transport roll advances developer material from a chamber to a donor roll. The donor roll advances the toner particles to the latent image. The latent image attracts toner particles from the donor roll. In order to improve the speed with which toner particles removed from the donor roll are replaced, an alternating voltage is applied between the two rolls.The magnetic transport roll is driven to rotate at a surface velocity at least 2, but not more than 5 times that of the rotational surface velocity of the donor roll. Also, the compression pile height (CPH) vs the spacing between the spacing between the donor roll and the transport roller (DRS) is found to be optimal when meeting the ratio CPH:DRS=2:3.

Abstract: An apparatus in which developer material comprising carrier granules and magnetic toner particles is transported closely adjacent to a latent image. The developer roller transporting the developer material is electrically biased. The electrical bias has a wave form that removes a substantially uniform distribution of magnetic toner particle sizes from the carrier granules and develops the latent image therewith.

Abstract: An apparatus which transfers successive different color toner images from a photoconductive belt to a sheet. The toner images are in superimposed registration with one another. Transfer efficiency of successive toner images is improved by neutralizing the charge on the toner image prior to the transfer of the next successive toner image to the sheet. This is accomplished by passing the sheet with the toner image transferred thereto between upper and lower neutralization corona generators. The upper neutralization corona generator applies a charge on the toner image having an opposite polarity to the normal polarity of the toner image. The lower neutralization corona generator applies a charge on the backside of the sheet having the same polarity as the normal polarity of the toner image.

Abstract: An apparatus that monitors the quality of copies reproduced by a printing machine. A signal of an image to be reproduced by the printing machine is transmitted to an electronic subsystem. The electronic subsystem converts the signal to a reference bitmap and transmits the reference bitmap to a raster output scanner in the printing machine. The printing machine reproduces the image on a copy sheet. The image reproduced on the copy sheet is scanned by a raster input scanner and a scanned bitmap generated. A comparison is made between the scanned bitmap and the reference bitmap to determine if the image reproduced on the copy sheet is at an acceptable quality level.

Abstract: An apparatus in which an electrostatic latent image recorded on a photoconductive belt is developed with toner. A donor belt is wrapped about a portion of a magnetic roll to define an extended loading zone. The magnetic roll advances a developer material comprising carrier and toner to the loading zone. At the loading zone, toner is deposited on the donor belt. A plurality of electrode wires are positioned in the space between the donor belt and the photoconductive belt. The electrodes are electrically biased to detach the toner from the donor belt so as to form a toner cloud in the space between the electrodes and photoconductive belt. Detached toner from the toner cloud develops the latent image.

Abstract: An apparatus in which a sheet is registered during the movement thereof. The sheet is moved along a path in a forward direction of movement and a lateral direction of movement substantially normal thereto. The lateral movement of the sheet causes the side edge of the sheet to engage a registration edge so as to be aligned thereat. The magnitude of the moving force applied on the sheet is proportional to the thickness of the sheet. In this way, the moving force varies as a function of the thickness of the sheet with the sheet slipping laterally when engaging the registration edge to prevent buckling thereof.