Abstract: A circuit providing digital representation of an analog error voltage present as an output of a bridge circuit where the digital representation is independent of supply voltage variations to the bridge circuit. The circuit shows a capacitor designed to ramp from an initial voltage representative of the zero point of the analog error voltage range to a full-scale error voltage in the amount of time it takes for a digital counter to count from zero to full scale. The ramping voltage is compared to the error voltage in order to decode error count whenever the ramping voltage reaches a value just in excess of the error voltage.

Abstract: A continuously variable reduction optical system for document copiers including various embodiments. A scanning optical system embodiment is disclosed for corner referenced documents. Full-exposure optical system embodiments are disclosed for both single-edge referenced and corner referenced documents. The systems can make use of single focus lens or variable focus lens. Specific mechanisms are disclosed for continuously variable adjustments to magnification, to total conjugate length, to image position, to scan speed and scan length and to leading edge registration. All adjustments are tied together under the control of the machine operator.

Abstract: A document feed mechanism for a copier machine incorporating an automatic document feed (ADF) with a semi-automatic document feed (SADF) and enabling the SADF to interrupt the ADF. The ADF tray upon which a stack of documents to be copied is placed is situated directly above the viewing station. A wave generator (shingler) paper feed means fans out the topmost sheets on the stack and up a ramp until the topmost sheet enters closed nip rollers. The nip rollers, together with aligner rollers and a drive belt, move the sheet around a substantially 180.degree. bend and onto the viewing station. Second sheet feeds are prevented by a restraint pad positioned between the nip rollers and the exit of the ramp, the top of the restraint pad being above the nip of the nip rollers so that the topmost sheet presses a second sheet downwardly into the restraint pad. The SADF feeds sheets onto the viewing station using the aligner rolls and the drive belt.

Abstract: In a document copier machine an almost completely enclosed optics module is provided to keep the optical components isolated from the remainder of the machine and thereby minimize contamination of the optical components. The described module has three large openings. One of these openings is an air inlet which opens to the exterior of the machine for bringing cooling air to a fan located inside the module. The second opening is an air outlet to allow the optics cooling air to exit. The third opening is critical to contamination and is an aperture which opens to the interior of the machine to allow illumination to pass from the optics module to a photoreceptive surface. In order to prevent air flow into the module through the aperture, louvers are situated at the fan to direct an airstream onto a first Coanda surface to move air toward the aperture.

Abstract: A system for checking copy quality variables within the image area of an electrophotographic machine. During a test cycle, quality is checked by producing sample test areas within the photoconductor image area ordinarily used for producing copies. Reflectance measurements are made on the sample test areas and compared to a dynamically floating reference achieved by a reflectance measurement from a cleaned portion of the photoconductor within the image area. The testing circuit is balanced so that the same reflectance voltage should be generated whether the single reflectivity-sensing device is viewing a sample test area or a cleaned reference area. The system checks for quality variables such as toner concentration, image voltage and an abnormally low reflectance photoconductor and provides a partial check on its own fault-free condition during periods when it is not in use.

Abstract: Apparatus and method for pinning the value of a white, gray or otherwise colored, single-shaded vector in an electrophotographic machine. The vector is the value of the image voltage minus the developer voltage. Valuation of changes in the image voltage are obtained by (1) sensing the reflectivity of a developed single-shaded image and converting that into a representative voltage; (2) sensing the reflectivity of the bare photoconductor and converting that into a representative voltage; (3) obtaining a comparison of the representative image and reference voltages; and (4) noting changes in the comparison. Pinning the vector calls for adjusting the member for producing the vector such as the developer voltage or document illumination intensity level an amount necessary to compensate for the change in image voltage.

Abstract: Paper aligning rolls wherein the drive roll is skewed to the direction of travel in order to move paper toward a referencing edge while the backup roll is oppositely skewed to urge the paper away from the referencing edge. By selecting the coefficient of friction of the drive roll to be higher than the coefficient of friction of the backup roll, the paper is moved into the referencing edge with a controlled small resultant force tending to not crumple the paper. This system maintains a high forward drive force while minimizing the force tending to crumple.

Abstract: A system for checking copy quality variables within the image area of an electrophotographic machine. During a test cycle, quality is checked by producing sample test areas within the photoconductor image area ordinarily used for producing copies. Reflectance measurements are made on the sample test areas and compared to a dynamically floating reference achieved by a reflectance measurement from a cleaned portion within the image area of the photoconductor. The testing circuit is balanced so that the same reflectance voltage should be generated whether the single reflectivity-sensing device is viewing a sample test area or a cleaned reference area. The system checks for quality variables such as toner concentration, image voltage, and an abnormally low reflectance photoconductor and provides a partial check on its own fault-free condition during periods when it is not in use.

Abstract: A movable self-contained deflector unit for directing sheets into the paper bin of a multi-bin collator. A first motor is mounted on the frame of the deflector unit to drive transport rolls also mounted thereon. The transport roll provides the final impetus for moving the sheets into the collator bin. A second motor is mounted on the frame of the deflector unit to drive the unit to a selected bin. The motor may be reversible in order to approach a selected bin from either direction. Alternatively, movement of the deflector unit in the second direction may be obtained through a spring motor wound through deflector unit movement in the first direction. Speed of the spring-driven deflector unit is controlled by dynamic braking of the second motor. This collator may interact with a copier machine to provide semi-automatic duplexing and the speed of the transport rolls may be synchronized with the speed of the copier for moving copy sheets into bins while the sheet is still in the final processing station.

Abstract: An electrophotographic machine of the transfer type wherein a modular construction is provided including a main slide-out drawer upon which the entire paper path is mounted as well as the transfer corona. Included in the main drawer are the paper supply bins, paper feeding mechanisms, transport guides and conveyors, the transfer corona, detach means, and the fuser. The paper supply bins are mounted in individual mini-drawers separate from but located within the main drawer.

Abstract: A magnetic-brush developer for use in an electrophotographic machine wherein the magnetic brush is used to transport toner-coated carrier particles to an elevated development zone from a pickup zone. A path for so moving the carrier is provided between the magnetic brush roll and an overflow plate, the lower end of which also serves as a doctoring blade. The carrier is moved to the top of the roll where a doctoring blade limits the amount of carrier entering the development zone. Excess carrier is accumulated in an expanded spatial area near the doctoring blade and returned to the vicinity of the pickup zone by falling back between the overflow plate and the housing. An area is provided near the doctoring blade at the top of the roll where no magnetic field is present. The overflow plate is made of non-magnetic material.

Abstract: Method and apparatus for automatically producing a duplexed copy in a document copier machine wherein the leading edge of the rectangular copy sheet is maintained during both passes through the machine and wherein both simplexed and duplexed copies may be collated. This method and apparatus is especially useful when the leading edge is the narrow dimension of the rectangular copy paper.

Abstract: An electrophotographic machine of the transfer type in which tetrafluoroethylene-coated carrier beads transport toner particles to a development zone by virute of the triboelectric attraction between positive toner and negative tetrafluoroethylene. At the development zone, the carrier beads are crushed together and occasionally a piece of tetrafluoroethylene is worn off of the surface of the beads and carried along on the surface of the photoconductor. These tetrafluoroethylene-wear products are subjected to high level preclean corona current to reverse the triboelectric negative polarity thereof. In that manner, a positive wear product is made to act as though it was toner and is therefore carried out of the machine on copy paper. In a similar manner, paper dust and other contaminants on the photoconductor surface are subjected to a high level preclean corona current to receive a positive charge for being carried out of the machine on the copy paper.

Abstract: A continuously variable magnification optical system for use in document copier machines wherein multiple cams are used to provide motion input to the continuously variable drive system. Multiple cams are used in order to provide capability to the machine of copying at 1:1 reduction on various size copy papers without causing the scanning mechanism to scan beyond the usable length of the document glass. A cam-select mechanism is disclosed.

Abstract: A continuously variable reduction scanning optical system wherein a preferred embodiment is disclosed with mechanisms for continuously adjusting the magnification ratio, the total conjugate length, scan speed, scan length, and leading edge registration. Either a single focus or variable focus lens can be used.

Abstract: The optical system disclosed is incorporated in a copying machine and has provision for changing magnification of original documents of diverse sizes while maintaining a common image plane projection and enabling the use of common reference edges at a selected reference corner for any original document that might be used and also maintains common reference edges in the image plane. The system contemplates the combined movement of the lens element as well as one of a pair of mirrors to insure that the original document surface and the image plane remain in their fixed positions, regardless of the magnification factor chosen. The lens element is movable forwardly and reversely along the optical path as well as transversely with respect thereto.

Abstract: The optical system disclosed is incorporated in a copying machine and has provision for changing magnification of original documents of diverse sizes while maintaining a common image plane projection and enabling the use of common reference edges at a selected reference corner for any original document that might be used and also either maintains common reference edges in the image plane or produces borders on the reduced-sized image without deliberately causing the center of the reduced image to coincide with the center of the non-reduced image. The system contemplates the combined movement of the lens element as well as one of a pair of mirrors to insure that the original document surface and the image plane remain in their fixed positions, regardless of the magnification factor chosen. The lens element is movable forwardly and reversely along the optical path as well as transversely with respect thereto.

Abstract: A continuously variable reduction optical system for document copiers wherein a plurality of sets of reduction indicators are provided, each set corresponding to a particular size copy paper. Each set of indicators can be moved by the operator to frame the document to be copied and simultaneously the reduction optical system is set to provide proper adjustment for all system parameters. The indicators are continuously viewable by the operator. An embodiment is disclosed wherein each indicator is positioned so that reduction ratio is maintained whatever the copy paper size.

Abstract: Method and apparatus for adjusting the position of a single-focus lens at two positions in a continuously variable reduction document copier machine. Adjustment is made at a 1:1 ratio by shifting the position of the lens on its carriage and adjusting the position of optical path mirrors until focus is obtained. Adjustment is made at a nominal 0.647 reduction ratio by adjusting the position of the lens carriage until focus is obtained. Apparatus is disclosed which provides the second adjustment without affecting the position of the lens at the first adjustment position.

Abstract: An illumination system of particular use in document copiers wherein an incandescent lamp which may be of the tungsten-halogen type is located at the focal point of a reflector shaped as a conic section such as elliptical cylinder, directing light rays toward an interference filter for separating the IR radiation and redirecting the IR rays back to the incandescent lamp for heating the lamp. Both cold mirror and hot mirror embodiments of the system are disclosed.