Abstract: Print enhancement circuits for an electrophotographic printing machine are placed between the character generator and the printhead to modify drive signals for the printhead. Modifications include smoothing the digitized edges of slanted lines; broadening single pel width lines in the direction perpendicular to the scan direction as well as in the direction parallel to scan. Inhibiting circuits are provided to prevent passage of enhancement signals under certain conditions. Generally, leading and trailing edge gray signals are provided next to all black data in a direction parallel to scan while expanded black signals are provided for the single pel data in a direction perpendicular to scan by adding to the black signal on both its leading and trailing edges.

Abstract: This describes a vibrating probe for measuring electrostatic surface potential. A multilayered piezoceramic bender element assembly is provided with a multilayered shield surrounding the bender assembly on all sides except for one opening window. The conductive sense element of the bender assembly is located in the window and is positioned near the surface to be measured. The bender assembly includes a conductive layer sandwiched between a drive piezoceramic layer and a feedback piezoceramic layer. The feedback piezoceramic layer is coated (on the side opposite to the inner conductive layer) with the conductive sense element and with a separate conductive area for connection to a drive oscillator. The multilayered shield is comprised of inner and outer conductive layers sandwiching an insulator. A circuit is provided whereby the sensed signal floats on a high voltage signal applied to the conductive layers of the shield.

Abstract: A common memory interfacing circuit and method for coupling a memory to either a synchronous bus or an asynchronous bus. Synchronizing means are provided for synchronizing memory request signals with a local clock when the interfacing circuit is coupled to an asynchronous bus. The interface circuit responds to signals from the memory when internal memory operation has been completed and generates an acknowledge signal to send to the requesting bus. To simplify the common interface circuit, a synchronous protocol for information exchange between system components is made similar to an asynchronous protocol.

Abstract: A mounting mechanism for the backup roll of a roll pair wherein a four bar linkage is provided. The backup roll is mounted at one end of a first arm and bears against a mating roll positioned in a stationary location. The first arm extends to a pivot point around which the backup roll rotates to engage the mating roll. A second arm is rigidly connected to the first arm at the pivot point and extends to an end point. A third arm, comprised of a coil spring with a coupler threaded thereto, extends from the end point of the second arm to a stationary point. The fourth arm of the four bar linkage is the ground extending between the stationary points to which the first and third arms are attached. By adjusting the coupler, the number of active coils in the third arm is adjusted thereby adjusting the normal force between rolls to a desired value.

Abstract: This discloses an electrophotographic printing machine with circuits to enhance the printing of fine lines, such as lines of a single picture element (pel) in width. Provision is made for broadening such lines in one dimension by adding small "black" areas to each edge of the fine line in order to broaden it. In a second dimension, perpendicular to the first dimension, lines are broadened by placing gray pels next to black pels. The disclosure also discusses specific cases in which it may be considered desirable to inhibit the enhancement signals.

Abstract: An optical system for use with laser chips to counteract variations in wavelength produced by semiconductor chips, to counteract astigmatism effects common to laser chips, to counteract variations in the distance between the plane of emission of the beam and the plane of a collimating lens, to counteract variations in beam size in perpendicular planes, to counteract variations in the divergence angle of emission common to laser chips, and to counteract tilt variations caused by imperfect reflecting surfaces. The system includes an apertured achromatic doublet lens for collimating the beam, a cylindrical lens, a rotating mirror, and a combination of toroidal and spherical lens.

Abstract: An electrophotographic printing machine utilizing a scanning light beam to produce generated characters is disclosed. The start of character generation is controlled by the edge position of paper receiving the image. Edge position of the paper is sensed prior to entry of the paper into the print receiving station. Signal(s) representing the edge position are sent to data processing control means. The signals are converted into an appropriate shift factor for controlling the start of pel generation. In that manner, the image to be generated is shifted in accordance with paper position so that proper margins are maintained regardless of paper position.

Abstract: A method and circuit for using signature analysis testing techniques without deriving start/stop and clock signals from the device under test. In this invention, a start signal is derived from the output data stream by configuring that data stream to indicate when the test stream begins. The stop signal is derived by counting the predetermined number of data bit cells to be measured and issuing the stop signal when the count is reached. Data clock pulses are derived as a fraction of test system clock pulses at a frequency approximately equal to the bit cell frequency. The data clock pulse is located at the midpoint of the bit cell time so that the data stream is clocked into the signature analysis tester at a stable point.

Abstract: A continuously variable magnification/reduction scanning optical system for a document copier machine where the lens and total conjugate length adjustment are made prior to the copy operation without use of a special optics positioning motor. Optical component adjustment is achieved through use of the scan drive motor by coupling the scan carriage to the lens carriage during the set-up period and uncoupling the carriages during normal operation.

Abstract: A moving document copier machine with a hinged cover of a recirculating semiautomatic document feed device for pivoting away from the top surface of the machine to expose the document feed path and enable the copying of a book or like object. A spine or rail means is provided along one edge of the document feed path to receive the center break of an opened book. Roll means interior to the document feed path support that portion of the book to be copied as it moves across the viewing station while other rollers, exterior to the document feed path, support that portion of the book not to be copied. A gate is provided to register the book.

Abstract: A system for checking copy quality variables within an electrophotographic copier machine involving the production of a developed sample test area and a base reference test area on a photoreceptive surface. An optical transducer is used to view the test area and circuits are provided to produce an output signal indicative of quality. The circuit triggers itself by detecting a substantial change in transducer produced signal level when the sample test area is viewed, thus negating the requirement that the test circuits be operated under the control of the machine.

Abstract: A motor control circuit for providing high acceleration currents by providing a driver comprising a transistor operating in the saturated region in parallel with a transistor operated in the nonsaturated region. The saturated transistor supplies the heavy accelerating current while the nonsaturated transistor is controlled to provide an increasing current through the accelerating period to make up for drops in the current flows through the saturated transistor due to build up of back emf in the motor.

Abstract: Erase apparatus for use in an electrophotographic copier machine where an array of light-emitting diodes (LEDs) is placed adjacent a plano-convex-cylindrical entrance end of an optical element such that light rays from the LED array are directed through the optical element to its exit end. At the convex-cylindrical exit end, the light rays are directed to the photoconductive surface of the machine. The optical element directs the more intense light rays emitted from the LEDs near the central axis to the edges of the erasure footprint while the less intense rays emitted from the LEDs at larger angles from the central axis are redistributed to the central portion of the erasure footprint.

Abstract: A paper feed device to forward documents to be copied across a document glass utilizing foraminous rollers positioned above the glass at a slight angle to the direction of document movement to move the side of the document into sliding relationship with a reference edge during the forwarding operation. The angle is produced by a curved drive shaft and rollers at opposite ends of the drive shaft are at different angles to the direction of paper movement. The rollers and drive train are rigidly mounted on a plate which is nonrigidly carried in a frame which pivots about a hinge at one end of the document glass. The plate rests on the top surface of front and rear reference edges when the frame is closed to assure accurate positioning of the rollers in relation to the document glass. After completing the forward feeding of a document, it is reversed a slight distance to a registration position for the copying operation.

Abstract: Process for eliminating the need for a separate cleaning station in a one-cycle electrophotographic document copier machine of the transfer type. A backcharge corona generator is added to provide an overcharge/backcharge process to obtain the desired level of charge on the photoconductive system prior to exposure of the photoreceptor to the subject. In that manner, residual toner remaining on the photoconductor after production of the previous copy is cleaned simultaneously with the development of the succeeding copy.

Abstract: A system for minimizing contamination of an electrophotographic copier machine wherein toner particles and/or carrier beads are the contaminating agents. The leading edge of corona housings is positioned a substantial distance from the surface of a rotating drum so as to not affect the rotating boundary layer near the drum surface. In that manner, vortex formation within the corona housings may be prevented. The trailing edge of corona housings is given a curved shape and is at least as far removed from the drum surface as the leading edge. The system includes a vacuum scavenging chamber to remove toner particles entrained in the boundary layer. The leading edge of the scavenging chamber is given a curved shape to create a venturi in order to draw the boundary layer into the vacuum. Carrier beads are removed in the scavenging chamber since the broad curved leading edge interferes with fringe fields holding carrier beads to the surface.

Abstract: A three piece aperture comprising a centerpiece positioned much as an "island" between two outer pieces so as to form two light transmissive slits. The two outer pieces may contain symmetrical light transmission edges. The aperture is of particular use in electrophotographic copier machines where substantially continuously variable reduction is practiced.

Abstract: Erase apparatus for use in an electrophotographic copier machine where an array of light-emitting diodes (LEDs) are placed adjacent one end of a light channel with the other end adjacent a moving photoreceptive surface. The channel allows light rays to pass freely from LED to LED but contains the rays in a direction parallel to the direction of photoreceptor movement. The channel may be comprised of sides with reflective surfaces normal to the photoreceptive surface or may be a solid plastic sheet through which the rays pass. In the latter embodiment, rays are internally reflected from the surfaces of the plastic sheet.

Abstract: An electrophotographic copier machine with a roll fuser where one of the mating rolls is comprised of a thin outer shell which takes a variable taper so that a concave shape is produced under high humidity conditions and a relatively straight roller is produced under low humidity conditions. Means for changing the support at the roll ends is provided to produce the variable taper. End plugs can be moved axially inward at high humidity to provide support for the end portions of the normally concave roll and can be moved axially outwardly under low humidity such that no support is provided until the roll ends are flattened under the pressure of a mating roll.