Abstract: Facsimile or other data to be reduced is scanned and segmented into blocks of isolated figures. The figures are compared to stored templates. If no match is found, the figure remains in place. If a match is found, the figure is erased, i.e., the block is reduced to white. When recognized figures have been erased, the residual image is transmitted using an efficient known two-dimensional encoding compression technique. The locations of figures are specified by inserting identifying data in the data stream at a point corresponding a point on the figure, the preferred point being the lower right-hand corner. If not a recognized template, the receiving end can extract the figure constructed from the data stream and store it in its template memory. If a figure is a recognized template, it is extracted from the receiving end's template memory using the identifying data and inserted into the reconstructed residual image.

Abstract: A document distribution terminal is organized with two supervisory processing units, one to control the data entry and data printing and the other to control the terminal. Each of these processing units only performs control functions. All of the data processing is performed by various specialized devices preparing the document data for transmission or for printing. Further, the terminal is organized with two interfaces and an adapter coupling the two interfaces. The terminal-controlling processing unit supervises one interface that interconnects all of the specialized devices. The other processing unit, that controls the data entry and data printing devices, supervises the second interface. Once the supervisory processing units have set up a job in the terminal, the data transfer across the two interfaces is substantially under the control of logic in the adapter.

Abstract: A document distribution terminal can be required to process large volumes of data. To do this rapidly and efficiently, the terminal herein is organized to process all of the data in specialized peripheral devices. A supervising central processing unit (CPU) controls the terminal but does not perform any data processing. The functions of entering data, scanning documents, encrypting data, compressing data, transceiving data, decompressing data, decrypting data and printing data are all performed in parallel by specialized devices working directly with a memory. A peripheral processing controller is initialized by the CPU. The controller then controls time-shared access to the memory by the specialized devices, such as devices used for processing data representing facsimile images.

Abstract: Developer mix is purged from a magnetic brush developer in a xerographic copier or printer by moving the pick-up zone of a magnetic brush roller out of the throw-off zone of a magnetic transport roller. A purge door is located adjacent the throw-off zone. In a purge operation, a catching container is attached to the developer at the purge door. The purge door is opened, and the magnets of the magnetic brush roller are rotated so that the pick-up zone of the brush moves out of the throw-off zone of the transport. The developer is then driven, and the developer mix moves through the developer, out the purge opening and into the catcher.

Abstract: In a multinozzle ink jet printing system, a closed loop servo system drives the drop generator so that the distance between the streams at which ink droplets are detached is maintained at an optimum range. One or more sensors are positioned downstream from the multinozzle plate of the ink jet printing system. The sensors sense the flight time of ink droplets and output signals which are developed into a variable voltage for controlling the drop generator.

Abstract: A linear image sensor and the video channel associated with the sensor are calibrated to maximize the video signal available. The sensor is limited in output by saturation of the CCD analog shift registers in the sensor. The channel is limited by the range of the analog-to-digital converter in the channel. The useable video signal is maximized by calibrating the sensor relative to its saturation condition and by adjusting the gain of the video channel relative to the range of the analog-to-digital converter. The sensor is calibrated by adjusting its exposure to illumination. The adjustment may be made by adjusting the illumination source or by changing the sampling interval for the sensor. The gain is adjusted by using a variable gain amplifier. A microprocessor monitors the digitized video signal and controls the exposure and gain to calibrate the sensor and channel.

Abstract: In continuous flow ink jet printers, over 95% of the ink in the ink reservior is recirculated each time the volume of ink in the reservoir is cycled through the printer. The apparatus herein provides a very low evaporation rate for the recirculating ink. With a low evaporation rate, the ink may be replenished with ink alone rather than having to supply ink concentrate and solvent to readjust the ink composition. The low evaporation rate is achieved by keeping the temperature of the ink in the reservoir and at the print head near ambient temperature of the printer's environment and by minimizing the air flow through the reservoir. In addition, the ink in the reservoir is replenished as it is consumed.

Abstract: The ingestion of air into the print head of an ink jet printer is controlled by a secondary fluidic system. The secondary fluidic system interconnects the ink supply cavity of the head with the primary fluidic system of the printer. The secondary fluidic system includes a valve which is coupled to a venting port of the print head. A rapid decompression regulator is coupled to the valve. The exit port of the regulator is attached to one end of a conduit. The other end of the conduit is disposed in a fluid-containing reservoir. The reservoir serves as an expansion/contraction chamber and keeps air from entering the head even under extreme thermocycling conditions. Likewise, the regulator controls the pressure in the head so that head pressure (P.sub.h) is greater than or equal to ambient pressure P.sub.a. This pressure differential prevents air from entering the head.

Abstract: Multiple-resolution, interlace, ink-jet printing is accomplished pseudo a single array with multiple nozzles by assuming a psuedo pel (picture element) spacing k' between the nozzles. The ratio between the old resolution and the new resolution is k'/k where k is the actual pel spacing between the nozzles. The print-data must be processed and the print head moved based on the pseudo pel spacing k'. The array of nozzles will still print in an interlace manner so long as k' and Nt (the total number of ink jet nozzles used) have no common factor.

Abstract: A receiver for demodulating a single sideband signal which is subject to rapid phase jitter employs a Hilbert splitter for obtaining the Hilbert transform of the single sideband signal, and a local oscillator for signal demodulation. A post-oscillator feedback loop instantaneously derives the amount of phase jitter in the single sideband signal, and employs the derived phase jitter to adjust the phase of the local oscillator so that the local oscillator tracks the single sideband signal.Instantaneous derivation of the phase jitter is obtained because all post-oscillator signal manipulations are algebraic; post-oscillator Hilbert transform generation is not required. A first embodiment derives the exact amount of phase jitter. A second embodiment, more simple than the first, derives the approximate amount of phase jitter.

Abstract: A peripheral processing controller controls access to a peripheral memory by specialized peripheral devices. The specialized peripheral devices process all of the data independently of a central processor that simply supervises the system. The controller uses Memory Address Registers (MARs) to control the access to the memory by the peripheral devices. Each peripheral device selects a MAR, and each MAR includes a mode register. The start address and mode are set in each MAR by the supervising central processor. Also, each peripheral device is set by the processor to select a MAR. When the controller grants each peripheral device access to the peripheral memory, the peripheral device uses whatever mode and starting address has been initialized for the MAR selected by the device. Each time the device accesses the memory, the address in the MAR is incremented so the MAR is ready for the next access. In this way, a peripheral device will advance through a block of memory space.

Abstract: A fluorescent lamp is adjusted in illumination intensity by controlling the DC current in the lamp during each alternate direct current flow through the lamp. The magnitude of the current applied to the lamp is set each time the direction of current through the lamp is switched, and the current change between switch times is limited. Inductors are used as current change limiting devices so that in each direction of current flow through the lamp, the current can not rapidly change. The amount of current is set, and the direction of current flow is switched when a current monitor detects that the current through one of the inductors is equal to the current desired for the operating point of the lamp. In this way, uniform selectable illumination levels may be achieved even though the lamp is operating in the negative resistance portion of its resistance characteristic.

Abstract: An ink jet pump is switched from a mechanically off or idle state to a mechanically on or active state with no drift in pressure output by maintaining the pump at the same point in its force-temperature characteristic when it is on and off. This is accomplished by driving the pump in both the active and idle states with signals that dissipate the same amount of power in the pump. The frequency of the idle state signal is high enough that the pump can not mechanically respond. The power dissipations in the active and idle states are matched by adjusting the current build-up and current decay through the coil of the pump during the idle state. When the RMS current through the coil in the active state equals the RMS current in the idle state, the power dissipations are matched.

Abstract: An illumination system for a document scanner comprising a fluorescent lamp for illuminating a document to be scanned and an efficient light guide which "pipes" the light to the target document area. The fluorescent lamp has an aperture defined by an aperture angle wherein the lamp radiance is determined by the aperture angle. The light guide has a trapezoidal longitudinal cross section. An input window associated with the narrow base of the trapezoidal shape light guide is coupled to the aperture of the lamp. An output window associated with the wide base of the trapezoidal shape light guide is directed to the document area.

Abstract: The apparatus shown herein controls a facsimile system to reduce four source documents and print all four reduced copies on a single copy page. The facsimile system prints one of the source documents in each quadrant of the copy document. The images of the source documents are reduced in the horizontal dimension by discarding every other picture element in the scan image. The images are reduced in the vertical dimension by increasing the scanner speed so that the size of the picture element in the vertical dimension is doubled. At the receiver, two scanned and reduced images will be printed on the left-hand half of the copy document. Subsequently, two additional scanned and reduced images are printed on the right-hand half of the copy document. When printing the right-hand half of the copy document, the printer must be referenced to start printing at the horizontal mid-page of the copy document rather than the left-hand edge of the copy document.

Abstract: In an ink jet printer, it is desirable to compensate the flight of the ink drops to correct for print errors caused by aerodynamic effects. The apparatus shown herein corrects the flight of ink drops for all aerodynamic effects, drop interactive and environmental. Correction for drop interactive effects can be accomplished in any of several well known ways. The additional correction for environmental effects is accomplished by scaling the drop interactive correction. The scale factor is first determined for static environmental conditions. Environmental conditions include the climate in which the printer operates and the specifications on the component parts of the ink jet printing assembly. The scale factor can be adjusted dynamically for changes in the environment. In particular, changes in air density of the environment are monitored and used to dynamically adjust the scale factor.

Abstract: A driver for an electromagnetic device, e.g. a solenoid, is capable of driving the device at a fast cycling rate while dissipating minimal power. In response to an actuating signal, a capacitor connected to a high voltage source supplies a high level current to the device for a short time interval until the capacitor is charged. Thereafter, a resistor connected to a low voltage source, supplies a low level current to the device, thus minimizing power dissipation. In response to the cessation of the actuating signal, a transistor connected in parallel with the capacitor turns on, and acts as a low impedance in parallel with the capacitor, to rapidly discharge the capacitor. Once discharged, the capacitor again may supply high level current to the device when the actuating signal is reapplied.

Abstract: The invention relates to an ink jet printer and in particular to correcting the flight path of drops from the printer to reduce print position error on the print media. Compensation values can be stored and retrieved for use by the printer to correct the flight of a drop to the print media. The compensation values are based on the pattern of print data representing the drops in the ink stream with the drop being compensated. To reduce the number of variables that must be dealt with, one or more portions of the print data can be grouped into one or more blocks and each block treated as having a single effect on the drop being compensated. However, basing the compensation value on one predetermined treatment of print drops as having individual effects or as having individual effects in combination with one or more group effects on the drop being compensated does not produce the optimum print appearance for all combinations of print data.

Abstract: A piezoelectric transducer forms a wall of an ink cavity, which has a linear array of ink jet nozzles communicating therewith. The piezoelectric transducer is preferably an arcuate sector of a cylinder having an angle no greater than 180.degree. with its mean radius, wall thickness, and its arcuate angle selected so that the arcuate sector vibrates only in a selected symmetrical mode at a selected resonant frequency when a voltage is applied at that frequency. The length of the transducer is chosen to be longer than the length of the linear array of nozzles so that the periodic pressure waves produced in the ink cavity by the transducer vibrating at the selected resonant frequency will have substantially the same amplitude at the entrance of each of the nozzles to form droplets of substantially uniform size and at substantially the same break-off point. The applied voltage selected is that which is necessary to produce uniformly satellite free droplets from the array of ink streams.

Abstract: A clamp for holding paper on a paper drum contains an aperture which may be optically scanned to detect the presence of paper in the clamp. The clamp is placed near the corner or edge of the document so that the registration of the paper will be known. A single detector scans the aperture as the registration clamp moves relative to the detector and looks for a dark-light-dark sequence of video signals to verify that paper is properly positioned in the clamp.