Abstract: Apparatus for adapting a common dc motor for use in a typewriter to drive the ribbon lift and advance functions. The motor is coupled by means of a set of gears to a shaft on which are mounted the ribbon advance gear and ribbon lift cams. Also mounted on the shaft is a slotted disk. As the motor and disk rotate, an optical sensor outputs a signal for each slot. A processor then computes the motor speed from the slot timing and issues modulated pulses to the motor to regulate its speed.

Abstract: A typewriter carriage cable snubber which is automatically reset at the time power is turned on is described. The cable is normally tensioned by a mechanism which is spring driven to maintain the cable tension at the proper value, and a snubber is provided to prevent the positioner from allowing the cable path to shorten under the increased tension that occurs during carriage acceleration. When the power is turned off, the cable tends to shrink due to the decreased temperature. When power is turned on, the carriage is initialized by positioning it at the left end of its range. At this position the cable tensioning mechanism can be reset to allow a shorter cable length by having an extension of the carriage disengage the snubber, allowing the positioning mechanism to reset itself to a shorter cable length.

Abstract: An apparatus that determines the density of the liquid developer in a xerographic system by depositing charged toner on a NESA glass segment, and optically measuring the density of the toner. A cleaning station is also provided. If the toner density is too low, more toner is added, and the test is repeated.

Abstract: In a high-density VLSI NMOS semiconductor such as a ROM, a voltage sensing mode amplifier in the output thereof, operative to sense relatively very low input signal swing bit read signals from the ROM with relative insensitivity to fabrication process variation. The structure includes a common gate amplifier for receiving the ROM signal, a very sensitive reference voltage circuit, a two-stage differential digital switching module operative to compatively receive the common gate and voltage reference signals to effectively distinguish relatively weak bit signals as read from the high-density VLSI ROM.

Abstract: A phantom formed of a non-biological material into the shape of a breast, said material having radiation characteristics of breast tissue, for use by medical personnel while in training to interpret mammographs, and as a tool to assess the quality of a radiological imaging system. The phantom material comprises one epoxy resin based tissue substitute which simulates the breast tissue, and another which simulates the skin tissue. A slot is formed in the phantom into which targets for simulating breast masses, fibers and calcifications can be placed.

Abstract: A circuit for correcting a raster input scanner or raster output scanner is described. During calibration, a calibration strip is scanned, the output of the light detector is compared to a reference voltage, and the difference is saved. This is a closed loop so that the difference value will settle at a value such that the detector output will accurately match the reference value before the final difference value is stored. In one mode, the correction is applied to one dynode of the PMT light detector, which varies the gain without varying the bandwidth of the circuit. The difference voltage is analog, but is stored in a digital memory through the use of A to D and D to A converters.

Abstract: A circuit for correcting for polygon drive motor velocity irregularities in a flying spot scanner is described. A crystal controlled oscillator is used to generate the system clock. As the motor speeds up, or slows down, pulses are subtracted, or added, to the stream of clock pulses so that the data bit stream will always occupy the same line length on the page regardless of polygon velocity variations.

Abstract: An improved edge extraction technique for use in copying a halftone original to produce a halftone copy is described. The prior art uses a two path system to rescreen a halftone, a filter path to remove the original screen and an edge extraction path to enhance the edges. The final gray scale signal, before rescreening, is the addition of the outputs of the two paths. This invention is an improved edge extraction technique for use in such a system. First, the sign and magnitude of horizontal and vertical edges is computed. Then a root mean square of these values is taken to provide a two dimensional enhancement. Next, the enhancement is tested against certain thresholds to test whether the value is a result of image noise, or whether there is a probability that a small enhancement may be in the wrong direction. Finally, the enhancement is added to the filter path output.

Abstract: The described circuit and method controls a thermal printer for loading into a print register that segement of a line to be printed that contains the exact number of black pixels that can be printed by the associated power supply, regardless of the length of the segment. The printer then continues to print segments until the end of the line is reached. Finally, the last partial segment of the line is printed, containing the remainder of black pixels. This method will achieve the maximum possible printing speed from a given power supply.

Abstract: An arm assembly for a disk drive having a read/write head and a servo head on the same Winchester arm assembly is described. To eliminate the possibility of crosstalk from the data head during the write mode, to the servo head, a mumetal shield is used to partially surround the servo head ferrite core and coil. The servo head is a composite structure having a non-conducting body and a thin ferrite core so that the magnetic core volume to be shielded is minimized. In addition, a conducting layer and a ferramic plate is interposed between the data and servo heads to further isolate these heads.

Abstract: An improved paper gripper bar is described. The upper and lower portions are made from extruded aluminum and hinge together for their entire length for greater stiffness. Two or three spring clips provide a bias for closing the bar. The paper is held between the bottom ends of the spring clips and the upper bar when the bar is in the closed position. Finally, the clips are assembled into grooves in the upper and lower portions so that no additional parts are required to maintain the gripper bar parts in their proper positions.

Abstract: An improved system for the automatic development of large xeroradiographic images. The system is arranged from left to right in the following order: the development station, the transfer station, the cleaning station, the input and output stations and the elevator. The transport system has two main levels, one to carry the exposed plate over the station to the left, the other to carry the plate through the stations to the right to develop an image. The top of the elevator serves as a relocation station and plates are stored in the bottom of the elevator. To save additional space, the development station moves to the left as the plate passes over it to the right.

Abstract: A circuit for correcting the data rate to compensate for polygon facet irregularities in a flying spot scanner is described. A crystal controlled oscillator is used to generate the system clock. As each facet becomes the current facet, a number of pulses appropriate for that facet are subtracted from the bit clock stream so that there will always be a constant ratio between data speed and scan speed regardless of the scan speed variations between individual facets.

Abstract: A method of enlarging or reducing the size of a halftone one bit per pixel raster image without changing the screen pitch is disclosed. First, there is a determination of whether the current byte is on an image edge using any edge detection means. If the current byte is on an edge, the nearest neighbor algorithm is applied to the original image on a bit by bit basis to prevent edge jaggedness. If the current byte is not on an edge, the nearest neighbor algorithm is applied on a byte by byte basis to prevent Moire patterns in the solid areas of the image.

Abstract: A xerographic system which makes two, or more, copies for each exposure by developing the image twice. This can be done by either providing two developing, drying and transfer stations within the system, or by reversing the direction of the exposed plate so that it is processed twice by these stations. This technique is possible because a large part of the image remains on the plate after the first development cycle.

Abstract: This is a circuit and method for adaptively selecting one of a plurality of predictor patterns to encode a stream of image data blocks such as would be output from a raster-input-scanner. A variety of halftone and nonhalftone predictor patterns are used and compared, with the best one being selected to predict the next block. Using this technique, the best predictor pattern is usually selected, predicted data buffering is not needed, and no code need be transmitted with the data to the receiver to specify the predictor to be used in the deprediction process since the same basic information is also available to the receiver.

Abstract: A circuit for controlling the hammer velocity of an impact printer is described. A velocity sensor generates a signal which is a function of hammer position. This is compared to a reference voltage, and a drive pulse is generated if a velocity correction is needed. The sensor can be located at the backstop and used to control the hammer velocity toward zero as the position nears the backstop. If the sensor is located at the backstop, the sensor output will remain constant for following velocity as its position approaches the backstop, allowing a constant reference voltage. A table look-up can be inserted in the circuit to supply corrections, for a sensor that does not have a position dependent velocity output.

Abstract: A circuit for use in an ink jet printer in which the carriage motion either approximates a sinusoidal vibratory pattern, or which has any variable velocity pattern that reliably repeats from cycle to cycle. It is further assumed that the printer will print in both directions of the carriage, and that the flight time of the ink drop from jet to paper is constant. A counter starts at a value corresponding to the flight time of the ink drop, and then measures the time of the carriage over a predetermined distance. The difference is the required delay. A second delay counter uses this value to produce a time delay prior to ejecting the ink drop. Since, in an actual ink jet printer, several drops will be in transit at the same time, the circuit is provided with a plurality of phases or channels which operate concurrently.

Abstract: A stepper motor controller which can control the motor to stop rapidly and with minimum overshoot and oscillation at a selected position by turning on and off one or several coils in a binary fashion to force the motor to conform to a predetermined position/velocity profile, resulting in the motor velocity and the position deviation from the null point to converge to zero at the selected null point. An encoder continuously generates current position and velocity data, a comparator compares the current velocity and position to a predetermined velocity/position profile to produce a binary output, and one or several motor coils are energized to drive the current motor velocity toward the predetermined value.

Abstract: This patent describes a user interface device (UI device) used for machine control. The UI device is comprised of a video display capable of presenting desired images to the machine operator and a touch sensitive device capable of detecting operator requests by means of the operator touching the surface of the video display. A standard keyboard may also be employed when typed responses are required of the operator or for infrequent use a QWERTY keyboard may be displayed on the Display. The UI device is controlled by a general purpose computer, which also controls the on-line machine. Visual elements presented to the user on the UI device's display include instructions in text (orthographic display), and images (imaginal display). Displayed images may include and log status indicators (E.g., meters, thermometers) and buttons which the operator can touch to signal control requests.