Abstract: Highlight color printing apparatus and method for forming one black and two color images. A tri-level image containing CAD and DAD image areas and a background area is formed. A second DAD image is formed by discharging the background area forming part of the tri-level image.

Abstract: Balanced, efficient corona transfer for both the charged area image and the discharged area image of a developed tri-level image is obtained by the provision of a selective pre-transfer charge corona device in combination with a pre-transfer discharge lamp. While improved transfer over prior art devices is obtained using a pre-transfer lamp prior to pre-transfer charging the preferred embodiment of the invention utilizes a pre-transfer lamp before and in coincidence with pre-transfer charging.

Abstract: Tri-Level Highlight color imaging apparatus utilizing two-component developer materials in each of a plurality of developer housings. The triboelectric properties of the toners and carriers forming the two-component developers are such that inter-mixing of the components of each developer with the components in another developer housing is minimized.

Abstract: In a tri-level imaging apparatus, a development control arrangement wherein the white discharge level is stabilized at a predetermined voltage and the bias voltages for the developer housings for charged area and discharged area development are independently adjustable for maintaining image background levels within acceptable limits. The white discharge level can be shifted to preferentially enhance the copy quality of one or the other of the charged area or discharged area images.

Abstract: Stabilization of the white or background discharge voltage level of tri-level images is accomplished by monitoring photoreceptor white discharge level in the inter-document area of the photoreceptor using an electrostatic voltmeter. The information obtained thereby is utilized to control the output of a raster output scanner so as to maintain the white discharge level at a predetermined level.

Abstract: Disclosed is an electronic printer employing tri-level xerography to superimpose two images with perfect registration during the single pass of a charge retentive member past the processing stations of the printer. One part of the composite image is formed using MICR toner, while the other part of the image is printed with less expensive black, or color toner. For example, the magnetically readable information on a check is printed with MICR toner and the rest of the check in color or in black toner that is not magnetically readable.

Abstract: Tri-Level Highlight color imaging apparatus and cleaner apparatus therefor. Improved cleaning of a charge retentive surface is accomplished through matching the triboelectric properties of the positive and negative toners and their associated carriers as well as the carrier used in the magnetic brush cleaner apparatus. The carrier in the cleaner upon interaction with the two toners causes them to charge to the same polarity. The carrier used in the cleaner is identical to the one use in the positive developer. The carrier of the negative developer was chosen so that the toner mixed therewith charged negatively in the developer housing.Thus, the combination of toners and carriers is such that one of the toners charges positively against both carriers and the other of the toners charges negatively against one of the carriers and positively against the other.

Abstract: A magnetic brush developer apparatus including a plurality of developer housings each including a plurality of magnetic brush rolls associated therewith. Conductive magnetic brush (CMB) developer is provided in each of the developer housings. The CMB developer is used to develop electronically formed images. The physical properties such as conductivity, toner concentration and toner charge level of the CMB developers are such that density fine lines are satisfactorily developed notwithstanding the presence of relatively high cleaning fields.

Abstract: A magnetic brush developer apparatus comprising a plurality of developer housings each including a plurality of magnetic rolls associated therewith. The magnetic rolls disposed in a second developer housing are constructed such that the radial component of the magnetic force field produces a magnetically free development zone intermediate a charge retentive surface and the magnetic rolls. The developer is moved through the zone magnetically unconstrained and, therefore, subjects the image developed by the first developer housing to minimal disturbance. Also, the developer is transported from one magnetic roll to the next. This apparatus provides an efficient means for developing the complimentary half of a tri-level latent image while at the same time allowing the already developed first half to pass through the second housing with minimum image disturbance.

Abstract: Printing apparatus for forming toner images in black and at least one highlighting color in a single pass of a change retentive imaging surface through the processing areas, including a development station, of the printing apparatus. The development station includes a pair of developer housings each of which has supported therein a pair of magnetic brush development rolls which are electrically biased to provide electrostatic development and cleaning fields between the charge retentive surface and the developer rolls. The rolls are biased such that the development fields between the first rolls in each housing and the charge retentive surface are greater than those between the charge retentive surface and the second rolls and such that the cleaning fields between the second rolls in each housing and the charge retentive surface are greater than those between the charge retentive surface and the first rolls.

Abstract: Apparatus for minimizing the contamination of one dry toner or developer by another dry toner or developer used for rendering visible latent electrostatic images formed on a charge retentive surface such as a photoconductive imaging member. The apparatus causes the otherwise contaminating dry toner or developer to be attracted to the charge retentive surface in its inter-document and outboard areas. The dry toner or developer so attracted is subsequently removed from the imaging member at the cleaning station.

Abstract: Undesirable transient development conditions that occur during start-up and shut-down in a tri-level xerographic systemw when the developer biases are either actuated or de-actuated are obviated by using a control strategy that relies on the exposure system to generate a spatial voltage ramp on the photoreceptor during machine start-up and shut-down. Furthermore, the development systems' bias supplies are programmed so that their bias voltages follow the photoreceptor voltage ramp at some predetermined offset voltage. This offset is chosen so that the cleaning field between any development roll and the photoreceptor is always within reasonable limits. As an alternative to synchronizing the exposure and developing characteristics, the charging of the photoreceptor can be varied in accordance with the change of developer bias voltage.

Abstract: An energy efficient means for selectively pre-magnetizing a magnetic recording medium of a thermoremanent magnetographic printer is disclosed. It consists of a pair of axially aligned, elongated two-pole, substantially cylindrical permanent magnets separated by a narrow gap and oriented so that like poles of adjacent magnets confront one another across the gap. The recording medium moves between the magnets in a direction perpendicular to the magnets. The elongated magnets produce magnetic field components that are additive in the surface of the recording medium and that cancel in the direction normal to the recording medium's surface. The magnetizing field of the magnets may be turned off for latent image retention by rotating the magnets about 90 degrees.

Abstract: An apparatus in which a supply of developer material stored in the chamber of a housing develops a latent image. A transport, disposed in the chamber, moves the developer material into contact with the latent image to form a powder image thereof. As developer material is depleted from the housing, the housing moves automatically toward the transport to furnish a continuous supply of developer material thereto.

Abstract: A method comprising a magnetic brush development system within a photocopier that circulates developer by the use of magnetic rollers includes deflecting members interposed between the rollers that are oscillated laterally to maintain homogeneity of developer circulating over the rollers.

Abstract: A magnetic mixing apparatus and process for mixing magnetizable developer material for use in the development system of an electrostatographic reproducing machine. In accordance with one embodiment a blanket of developer material is magnetically divided into a plurality of widely spaced apart streams. In accordance with an alternative embodiment, the blanket of developer material is magnetically divided into a plurality of closely adjacent or touching streams having different trajectories. Preferably the streams are then directed into one or more cross-mixing devices to provide enhanced side-to-side mixing of the developer.

Abstract: A magnetizable donor is magnetized to define a microfield with a characteristic spacing between pole centers of about 0.010 inches. The strong short range fields between poles pick up and hold a thin uniform and continuous layer of magnetic toner. The layer of toner is then electrostatically charged and brought into close proximity to a receptor, without touching the same, where only latent image areas of the receptor attract toner from the donor layer.

Abstract: A magnetic brush development system within a photocopier that circulates developer by the use of magnetic rollers includes deflecting members interposed between the rollers that are oscillated laterally to maintain homogeneity of developer circulating over the rollers.

Abstract: An apparatus which renders a latent image visible by depositing developer material thereon. The apparatus includes a tubular member having a styrene-butadiene layer coated on a nonmagnetic roll. Magnets are disposed interiorly of the tubular member to attract the developer material thereto. The developer material is transported into contact with the latent image to produce a powder image thereon.

Abstract: A magnetic brush development system including a spatially programmable electrode-type applicator roll for developing latent electrostatic images carried by an imaging surface of an electrostatic processor as the imaging surface moves through a development zone which is subjected to a substantially stationary, locally generated electrostatic field having a generally uniform intensity widthwise of the imaging surface and a preselected, non-uniform intensity lengthwise of the imaging surface.