Burroughs, Inc.

Daniel A Wisner

Jack Beery

Truman T Schmalzriedt

Andrew H McMillan

Flavius A Mathamel

Andrew S Mihalik, Jr

System for determining whether magnetic ink is present on specific areas of a document bearing magnetic ink characters. Signals are produced as a magnetic read head passes over the area in question on the face of the document. These signals are routed to apparatus which operates in response to the signals by providing outputs of a first kind when magnetic ink is present and outputs of another kind when ink is not present or is not present in sufficient amount to produce a signal exceeding a threshold value. Logic means responsive to the signals of the first and second kinds establish the presence or absence of magnetic material.

Intercharacter gap detector for MICRS

A voltage regulator for converting an unregulated input voltage into a regulated D.C. voltage. The voltage regulator includes a driver transformer which periodically receives energizing current from a voltage source through a transistor switch. A switching regulator controller regulates the conduction time of the transistor so as to control the amount of energizing current supplied to the driver transformer. The driver transformer secondary windings drive the base of output transistors which, when conducting, connect the primary windings of an output transformer to the voltage supply. A capacitor is connected in parallel with the primary winding of the driver transformer so as to short circuit the primary winding of the drive transformer when the driver transistor is turned off. The current flow in the secondary of the driver transistor causes removal of the stored base charge from the output transistors which decreases the turn off time of the output transistors. The primary windings of the output transformer are connected in series with first and second capacitors connected between the common junction of the primary windings and the voltage supply to effectively create a virtual ground at the common junction. One end of each of the secondary windings of the output transformer is connected to Schottky diodes arranged in a full-wave, center tapped rectifier configuration. A hollow ferrite sleeve is disposed around a conductor connecting each Schottky diode with a secondary winding and provides sufficient inductance to protect the Schottky diodes from transient reverse overvoltages.

Voltage regulator

An apparatus and process for detecting overlapped documents in a document processing apparatus by detecting the translucency of the documents. The disclosed apparatus includes a transport path for guiding documents and drive wheels for moving the documents along the transport path. Four LED (light source) phototransistor (light detector) pairs are located across the transport path. One LED-phototransistor pair is used together with electronics to detect when a document is present. Two LED-phototransistor pairs are used together with edge detection electronics to detect sudden significant changes in document translucency from the immediately previous translucency of the same document as the documents pass thereby. The other LED phototransistor pair is used together with level detect electronics to sample and hold the translucency level at the beginning of each document, and then to detect when the present translucency level of the document exceeds predetermined guardbands on either side of the translucency level at the beginning of the document as the documents pass thereby. Overlap indicating electronics indicates overlapped documents when the outputs of the two edge detects and the level detect are continuously coincident for 1 millisecond, and then the output of the level detect remains continuously present for an additional 5.6 milliseconds.

Document overlap-detecting apparatus and process

An apparatus is provided for controllably moving a load in a return mode back to a first or home position by a motor driven shaft, which shaft moves the load toward a second position in a forward mode to track a moving object field. An apertured fan-shaped timing disk or element is secured to the rotating shaft to move therewith. A position feedback sensor senses the angular displacement of the shaft by generating a feedback signal upon optoelectronically sensing an aperture in both the forward and return modes. An optoelectronic sensor detects the passage of the moving object field to provide a return signal after the object field has passed a predetermined position. A motor and its amplifier controllably move the load back to the first position in the return mode in response to the return signal. The inertia of the system causes the shaft to rotate to move the load to the second position in the return mode after responding to the return signal. A return home circuit is responsive to the difference in the number of feedback signals in the forward mode and the up-to-date or current number of feedback signals in the return mode to provide an accelerating bias signal and then a decelerating bias signal to the amplifier to accelerate and decelerate the load respectively as the load moves back towards the first position.

Return and position control for a DC servo system

D.C. power supply having a reactive buck automatic D.C. voltage regulator which directly controls the rectified D.C. output of a loosely coupled transformer thereby providing load regulation from an unregulated alternating current source. The load current passes through the secondary winding of an auxiliary buck transformer and is stepped down to a much lower value in the primary winding of the auxiliary buck transformer. The primary winding of the auxiliary buck transformer is coupled to an isolated winding on the core of a ferroresonant C.V.T. transformer which receives the unregulated alternating current input signal, and the coupling between the isolated winding and the primary winding of the buck transformer effects a bilateral energy transfer between the two transformers which effects a real time reactive compensation which regulates the D.C. output of the power supply for changes in the input voltage and in the load while conserving the energy which would normally be wasted in achieving regulation by transferring it back to the resonant circuit via the bilateral energy transfer between the two transformers. The control system is set up so that the auxiliary buck transformer is normally bucking under all line and load conditions when the frequency is precisely at the resonant frequency of the saturable inductor and capacitor. A frequency shift either above or below resonance simply changes the amount of bucking that takes place in a complimentary manner. It should be noted that little power is consumed during the buck process as the power is returned from the auxiliary buck transformer to the loosely coupled ferroresonant transformer. The operating point of a negative feedback system which determines the point about which the bilateral energy transfer occurs, may be fine-tuned by an error-sensing feedback circuit for altering the voltage level which the coupling network operates to hold constant by controlling the bilateral energy transfer. A capacitor is provided across the primary of the auxiliary buck transformer to reflect capacitance into the secondary winding during conditions of little or no bucking action in order to enhance the stability of the regulator.

High efficiency power supply having a reactive buck automatic D.C.

A system for detecting the occurrence of a fault in a solenoid utilization system when the fault is manifested by the solenoid armature or plunger being seated either too early or too late. A predetermined time interval is established such that the seating of the solenoid armature or plunger during this time interval is regarded as acceptable. A cusp detector circuit detects the point in time at which the solenoid plunger or armature seats and if it is within this predetermined time interval, it is recognized as acceptable, but if it is detected either too early or too late, an indication is generated that a fault exists and the occurrence and probable nature of the fault may be flagged. A test mode is provided whereby the predetermined established time interval can be considerably narrowed so that maintenance can be performed on the system so as to insure that the solenoid armature or plunger seats at exactly the proper time. As the predetermined time interval is narrowed, the acceptable range is narrowed and if the solenoid armature or plunger is found to seat a little too early or too late, it can be taken as an indication that a future failure is to be anticipated unless maintenance is performed. The system can then be recalibrated to insure that the solenoid armature or plunger seats at the proper time thereby averting a future failure.

System for predicting or detecting a fault in a solenoid utilization

An improved switching regulator converts an unregulated DC voltage into a regulated DC output voltage and maintains regulation over the entire range from maximum load current through zero load current. The improved regulator employs a plurality of series switching paths connected between the unregulated DC input and a summing node at a filter capacitor output. Each series switching path includes a power switching element, a catch diode and a series inductor. The other end of the summing node is connected through a current limiting circuit to the DC regulated output, and at least a portion of the voltage at the summing node is fed to a voltage error amplifier and used to control the duty cycle of the series switching elements. Feedback from the current limiting circuit can override the voltage error amplifier control should the maximum current limit be exceeded. The switching control means employs pulse-width modulation for adjusting the duty cycle of the series switching elements, and the technique of pulse-width modulation employed in the present invention is of the constant frequency, variable 'ON' time variety, as known in the art. The switching element control means utilizes a selecting means whereby different ones of the switching elements in different ones of the series switching paths are sequentially selected such that the selected series switching element is always turned on into a non-conducting inductor and a fully-recovered catch diode so as to minimize or eliminate the power loss associated with switch turn-on; the noise usually associated with switching regulators; and the turn-on transient which is often propagated into the supply line in the switching regulators of the prior art, thereby allowing highly efficient and reliable regulation to be maintained at very low values or even no value of load current.

High efficiency switching regulator

A digital tachometer for generating electrical pulses at a rate indicative of the speed of rotation of a shaft-like member. A first toothed disk having N teeth is affixed to the shaft and a housing having a second set of M teeth is fixed with respect to the shaft and positioned around the toothed disk. As the shaft rotates, individual ones of the teeth on the outer periphery of the disk which is affixed to the rotating shaft alternatively pass into and out of close proximity to individual ones of the teeth of the outer housing resulting in periodic increases and decreases in the reluctance of the system. A sensing coil is positioned with respect to the housing so as to generate an electrical current which varies as the reluctance changes from one polarity to another as the shaft rotates. At each point of maximum reluctance and at each point of minimum reluctance, the polarity of the reluctance and correspondingly the slope of the current waveform changes and these changes are detected by a slope-change detector circuit which generates a digital signal in response thereto. The rate of generation of these digital signals is therefore indicative of the speed of rotation of the shaft and the speed of rotation can be sensed over a very wide range from very slow rotational speeds to very high speeds.

Wide-range digital reluctance tachometer

A solenoid control system wherein the duration of actuation of a solenoid is a function of the workload imposed thereon so that the current to the solenoid is always turned off as soon as the solenoid plunger or armature is seated. Solenoid control logic responds to an external demand for the energization of the solenoid and enables a solenoid drive circuit which supplies current to the solenoid coil. The level of current builds in the solenoid coil until the solenoid plunger or armature is pulled in. The current continues to build as the solenoid plunger or armature is drawn in until that point at which the reluctance of the magnetic circuit is changing faster than the current in the solenoid coil is able to build. From this point until the solenoid plunger is seated, the current drops. As soon as seating has occurred, the reluctance ceases to change and the current once again begins to build in the solenoid coil. The change in reluctance and the termination of that change is represented by a cusp in the waveform of the current through the solenoid coil. A broad band cusp detector senses the point at which this change in reluctance ceases (i.e., when the solenoid plunger or armature seats) and generates a pulse which is supplied to solenoid control logic causing it to disable the solenoid drive circuit and turn off or reduce the current to the solenoid coil. The solenoid control logic further insures that the solenoid drive circuit is disabled in the event that the cusp-indicative pulse does not occur within a predetermined interval of time so as to conserve energy and protect the solenoid and associated circuitry.

Growing community of inventors

Milan, MI, United States of America

Daniel A Wisner