Abstract: A laser control circuit in which the laser is driven by a voltage controlled, current driver. At the beginning of each scan, an outer loop senses the laser power, and compares it at an outer loop summing junction to a predetermined value to generate a correction, and then applies that correction to the current driver through an inner summing junction. Within each scan, an inner loop detects the voltage across the laser and applies it as a correction voltage to the inner loop summing junction. The result is that at the beginning of each scan the laser power is set, and during the scan the voltage across the laser is held constant.

Abstract: A method of halftone printing in four colors using, for cyan, magenta and black, halftone screens that will result in screening angles of 15, 45 and 75 degrees, as is the standard process in the art, and a halftone screen for yellow that will result in screening angles of 0, +60 and -60 degrees. This combination will diminish the 2 color moire patterns that result from the interaction between the yellow and one of the other colorants. The 0 and + or -60 degree screening angles are generated by using a screen that produces a four-centered cell having dots that are spaced to form hexagons, when the nearest neighbors of a central dot are connected by lines, as opposed to the conventional trapezoidal orientation.

Abstract: A circuit for seamlessly printing data from a remote source that is arriving at a clock rate that is equal to the clock rate of the local data, but that has a different clock phase, due to the longer path used by the remote data. The circuit generates a number of local clock phases, compares these phases to the phase of the remote clock, and uses for both local and remote data the clock whose phase is nearest that of the remote clock.

Abstract: A circuit for rapidly rotating a digital image through 90 or 270 degrees utilizing memory implemented from ordinary 4-bit wide memory devices. This pipelined circuit transfers the image through a page buffer and a band buffer in a series of memory accessing, shining and reordering steps which converts all vertical lines to horizontal lines and all horizontal lines to vertical lines without requiring the use of a parallel to serial conversion.

Abstract: In a write white color xerographic system which builds up layers of color toner on a web prior to transfer to paper, the method of generating a toner mark on the belt on the first pass by use of the scanning laser, and of detecting that mark on subsequent passes to ensure registration of the first and subsequent passes. The marks are made on the photoreceptor slightly before and after the image area to indicate the area and shape of the image area, and are used in conjunction with ordinary start and end of scan detectors which are used to determine scan speed.

Abstract: A high voltage bipolar transistor fabricated on a CMOS substrate without adding any additional process steps. During the CMOS n-well mask and implant steps an n-well is formed for the transistor. Next, during the CMOS field and deep boron implant steps a circular p-field is formed within the n-well. Finally, during the CMOS p+ mask and implant steps the p+ emitter is formed. The presence of the p-field between the emitter and n+ base provides high voltage protection.

Abstract: When a field effect transistor is used to control the current through an inductive load, the flyback voltage is felt through the vertical pnp transistor at the drain, which onducts to the substrate. This current represents a power loss and a source of heat. This invention supplies a second lateral transistor which conducts this current back to the power supply.

Abstract: A selenium alloy electrophotographic imaging member having an optically transparent NESA coated substrate. An x-ray image is formed from the side of the photoreceptor opposite the transparent substrate and then is scanned from the back side through the transparent substrate with a fine beam of light, the position of which is precisely monitored. The ensuing discharge from the light beam is detected by a non-contacting x-ray transparent electrode located on the outer side of the photoreceptor, away from the substrate, which reads the discharge signal through capacitive coupling, pixel by pixel, according to the position of the light beam, to form a high resolution raster pattern digital readout of the image.

Abstract: A method is described for transferring data on a digital data bus system. The bus system includes a bus having a clock line for communicating a clock signal, address lines for communicating address signals, data lines for communicating data signals, and control lines for communicating control signals. A bus controller is connected to the bus. A plurality of devices are also connected to the bus. Each device has a predetermined address. The control lines include a bus grant line for communicating a bus grant signal that permits the devices addressed by the bus controller to send or receive data signals. According to the method, the bus controller generates a bus grant signal on the bus grant line and source address and destination address signals on the address lines. The devices receive the bus grant signal and the source address and destination address signals. The devices decode the source address and destination address signals in response to the bus grant signal.

Abstract: A set of halftone screens and a write white xerographic system for generating halftone images with a minumum of artifacts. The screens used in a four color printer have at least 64 pixels per pattern and are distributed to creat fourcentered dots that are at either -14, 0,+14 or +45 degrees. The xerographic process involves charging the photoreceptor, partially discharging the photoreceptor with a scanning beam to create an image, and then using toner which adheres to the charged portions of the photoreceptor to create the hard copy.

Abstract: A method for adjusting the weight of a character of an outline font to produce an adjusted character, the character and adjusted character being described by collections of control points that guide the drawing of line or curve segments, with each line or curve segment being described by two end control points and each curve segment also being described by at least one middle control point. According to the method, first and second lines are determined for each segment of the character. The first line is the line defined by the two end control points of the segment, and the second line is the line parallel to the first line and offset from the first line a predetermined distance in a predetermined direction. Next, first intersects are determined for each segment of the character. The first intersects are the intersects between the associated second line and the second lines of adjoining character segments.

Abstract: This invention consists of a pair of modules containing silicon power rectifiers which are wired into the existing ignition system of an automotive vehicle so as to increase the sparkplug life of the internal combustion engine and increase the gasoline mileage thereof.