Abstract: An installation for vehicles moving automatically, without human intervention, between starting and arrival points along a predetermined path consisting of stops, junctions, crossings, inlets, outlets of elevators, etc.An installation in which each self-propelling vehicle is adapted to carry a load and has steering-wheels and a central driving-wheel as well as optical detectors designed to read an optical track laid out on the ground and furnishing passive driving signals, the vehicle also being provided with an ultrasonic emitter-receiver assembly working as a radar and operative to detect obstacles along the path of movement of the vehicle.

Abstract: In a tracking servo system of a recording-disc information reading and reproducing apparatus such as a video disc player, a tracking error signal indicative of an amount of deviation of an information pickup medium such as a focused spot of a scanning beam of light from a target track of the recording disc being scanned is amplified with a gain which is varied as the pickup medium is displaced radially of the recording disc between an outer peripheral area and a central area of the disc.

Abstract: A video disc player featuring a signal correcting device capable of compensating for the attenuation of the signal level of high frequency components of the reproducing signal read out from an optically electromagnetically or electrostatically scanned video disc, a device for detecting the presence or absence of recorded information on a video disc being played back, or a tracking servo system which can be locked in reliably and in a stable condition when the servo loop is to be closed from an open condition.

Abstract: A tracking servo system of a video disc player, in which the switch provided in the servo loop of the system is closed and accordingly the servo system is locked in when the level of the reproducing signal read out from the video disc is at its peak or close to the peak and concurrently the amount of error between the scanning spot and the track to be scanned is of a minimum value.

Abstract: A video disc player is described for use with a video disc having frequency modulated video information recorded thereon in the form of a plurality of concentric circles or a single spiral. The information track comprises successively positioned light reflective and light non-reflective regions. A focused light beam is caused to be positioned over the center of an information track and the light reflected from the information track is gathered by an objective lens for application to electronic circuitry for recovering the recorded frequency modulated video signals. Radial tracking means are described for maintaining the focused light spot to impinge upon the center of an information track. Lens focusing means are described for positioning the objective lens at the optimum focused position above the information track for gathering the maximum amount of reflected light from the information track.

Abstract: Apparatus for non-contact tracking of a weld seam to provide lateral position guidance of a welding torch advanced along the weld seam by a traveling carriage utilizes an electromagnetic radiation source for directing an unfocused beam onto the weld seam producing a spatial distribution of reflected electromagnetic radiation having an optical center of power the location of which is functionally related to the lateral position of the welding torch relative to the weld seam, and a lateral cell position sensor for sensing a shift in position of the optical center of power of the reflected electromagnetic radiation spatial distribution. Detection of a shift in position of the optical center of power is utilized as an indication of lateral deviation of the welding torch relative to the weld seam.The apparatus disclosed further includes signal processing circuitry that develops an electrical signal indicative of welding torch position for input to a torch drive servomechanism.

Abstract: A system for determining the position of vehicles in an automated warehouse of the type utilizing transfer vehicles and robot vehicles is disclosed. The position determining system includes a photo-electric sensor flexibly coupled to a robot vehicle, which sensor is responsive to its alignment with a pallet stored in the warehouse. The system further includes a photo-electric reflector retaining bracket mounted adjacent to an aisle in the warehouse, the bracket supporting a number of reflectors arranged in a pattern containing information identifying the aisle. A photo-electric transceiver supported by a mounting bracket is connected to a transfer vehicle and is arranged to provide an output signal related to the pattern of the reflectors when the transceiver is in alignment with the reflectors whereby the transfer vehicle is apprised of its location in the warehouse.

Abstract: A servo control system for maintaining an information detection device, such as a light beam, centered on a moving information track, such as a spiral recording track on a video disc. The system of the invention includes an optical system, a piezoelectric dither element coated with a resistive material, a dither oscillator, circuitry for deriving an intermediate signal indicative of the effect of dither on the detected signal derived from the information track, phase comparison circuitry for deriving a known error signal from a comparison of the dither signal applied to the piezoelectric element and the actual dither modulation of the light beam retrieved from the information track.

Abstract: A method of and a system for tracing a monochromatically contrasting pattern on a uniplanar surface, in which signals indicative of a detected image of the pattern are produced by photoelectric transducer elements arranged in a two-dimensional or linear matrix array and signals indicative of a suitable number of modified reference areas displaced a predetermined distance from a prescribed basic reference area formed on a plane parallel with the uniplanar surface are produced from memory units having the modified reference areas registered therein, whereupon signals indicative of areas over which the detected image sensing zone is overlapped by the modified reference areas are produced to determine the direction in which the matrix array is to be moved with respect to the pattern on the uniplanar surface.

Abstract: A curve follower or line tracing system for converting the common representation of patterns of lines into features which are readily usable as inputs to an adaptive information processing system such as a Nestor adaptive module. The problem addressed by this system is how to sequentially identify, from a global exposure or tracing of a curve, the starting and subsequent points of the curve in the same manner as tracing it by hand. In the curve follower, an array of light sensitive elements located on a grid identify a line at the grid points. Since the end point of the line has a single neighbor, it is readily located. The identification of an end point is used to subsequently inhibit further identification of the end point and create another point which is similar identified. Overall biases may be employed to define a preferred line direction. Once the resulting sequence is obtained, the line may be coded.

Abstract: Disclosed is an interactive graphic apparatus for obtaining a desired formal drawing from a manuscript bearing rough drawings depicted thereon. In this apparatus, the operator can automatically draw onto a drawing paper put on a drawing table, on the basis of the positional information items of drawings on a manuscript disposed on a reading table and the functional information items inputted from a key board. The apparatus has particularly three component elements of digitizer, controlling device and plotter incorporated into an integral desk-like structure and various operational functions, whereby the interaction of the apparatus is improved.

Abstract: In a recording and/or reproducing apparatus having a rotated record carrier, for example, in the form of a disc, adapted to have video or other signals optically recorded in successive turns of a spiral track on a surface of the record disc, a recording and/or reproducing transducer or head assembly with an optical system including a movable lens for focusing a light beam at the disc surface and/or a movable mirror for deflecting the light beam so as to cause the latter to scan the track, and a servo system for detecting deviations from the proper focused and/or scanned conditions, for example, due to fluctuations of the rotated record disc in directions normal to, or in the plane of rotation thereof, and for correspondingly displacing the lens and/or mirror, respectively, so as to maintain the proper focused and scanned conditions; such servo system is provided with a gain-frequency characteristic having peaks at a fundamental frequency corresponding to the rotational speed of the record disc and at least at

Abstract: For focus and tracking controls for a pickup of an optical-type video disc player, wobbles are simultaneously applied to focus and tracking adjustment mechanisms. The wobble for focus and the wobble for tracking are effected by two signals 90.degree. phase-shifted from each other. The respective informations representative of focus and tracking errors are separately detected in a synchronous detection manner using the same two signals to provide focus and tracking control signals.

Abstract: An automatically guided vehicle wherein a guide line is positioned in a predetermined path on the floor and the vehicle has a sensing head positioned over the guide line to detect the position of the guide line with respect to the vehicle and to generate an error signal representative of the vehicle position with respect to the guide line. A control circuit is also provided on the vehicle to steer the vehicle responsive to the error signal generated by the sensing head. The sensing head includes a scanning head to scan across the guide line and to generate an output signal representative of the detected light values at discreet positions of the scan. The control circuit is adapted to steer the vehicle along the right edge, left edge or center of the guide line and is responsive to control codes positioned on the floor adjacent the guide line.

Abstract: An automatic arc welding machine includes a work monitoring device comprising a light source for projecting a light to the workpiece and an image taking device which receives the light as reflected by the workpiece. The light source is so controlled in accordance with the operation of the image taking device that the average intensity of the projected light is increased when the image taking device is in operation. The arrangement is effective to increase the signal-to-noise ratio.

Abstract: A scanner profiling system for locating and "mapping" a selected "feature" in a three-dimensional object, which "feature" is nearest with respect to a defined datum plane. The system includes a laser-distancing-instrument (LDI), and a cooperating motor-driven mirror apparatus which is operated under digital computer control to shift the scan axis of the system, in preselected steps, throughout a defined scan field. Object "feature" location, and related scan orientation data which are obtained during a scanning operation, effect computer scan control, whereby scanning "attention", within the total scan field, is directed particularly to "track" the selected "feature".

Abstract: An airplane or other vehicle is to be used for repeated traverses over an assigned area successively in respective different ones of a plurality of parallel paths displaced laterally one from another. Path alignment apparatus carried by the vehicle cooperates with delivery means that dispenses a material along each of the paths in a swath of predetermined width. The material includes an agent that presents characteristic radiation at a predetermined frequency. A sensing means is oriented to view the path of approach of the vehicle for detecting the radiation and developing a discriminated signal which distinguishes between presence and absence of the radiation. Developed by range-finding means is a distance signal that represents location of the vehicle relative to the location of the path being approached.

Abstract: A machine for tracing an outline of an original picture and recording the same outline image as the picture for making a cutting mask for photo-printing, which includes an optical head for receiving light from a light spot projected to the picture by a projector, detecting elements in the optical head which detect the outline of the picture and produce signals for controlling a driving arrangement, and a processing head for recording a locus of the outline onto the recording material, wherein the processing head has the same movement relative to the recording material as the optical head has relative to the original picture.

Abstract: A video signal play back device derives video signals from successive tracks formed as a continuous spiral on a video disc using a light source and a lens system, which is carried by a rotatable element at a predetermined spacing from the surface of the disc and which defines a folded optical path. The rotatable element translates the lens system in the radial direction relative to the disc for "coarse" steering of the light beam along the information tracks as the disc is rotated by a turntable. The optical path includes a mirror which is articulated for rotational motion about an axis which shifts the point of impingement of the transmitted light beam upon the disc in the radial direction. The returned beam is directed to a photosensitive pick-up which provides input signals to a circuit which generates a "fine" servo control signal to drive the articulated mirror.

Abstract: In accordance with a presently preferred embodiment of the invention, a source of radiation produces a pair of tracking spots focussed on a record carrier and nominally disposed toward opposite sides of a record track on the record carrier. After interaction with the record carrier, each of the tracking spots is detected to produce respective tracking signals. The components of each tracking signal which correspond to the information signal recorded on the record track are compared and a tracking error signal is produced based upon such comparison. By so producing the tracking error signal, proper tracking can be maintained irrespective of the polarity of the record carrier.

Abstract: In a video and/or audio disc player wherein a laser beam is focused by an objective on a record disc for scanning same along a spiral information track thereon, a focus control is provided which comprises a converging lens disposed across the path of the information-modulated laser beam. Two or three photodetector elements are disposed on one of the conjugate planes of the converging lens the other of which substantially coincides with a focal plane of the objective. Aligned in the direction in which the successive images of pits on the record disc travel thereover, the photodetector elements produce electrical outputs having a phase relationship representative of the variable distance between record disc and objective.

Abstract: An improved circular scan line tracing device for use in connection with flame or plasma cutting machines, as well as other machine tools, is disclosed which features provision for adjustment of the lead of the tracing device while the machine is operating.

Abstract: A digital servo system for maintaining a detection device, such as a light beam, centered as closely as possible over an information track, such as an optical track on a video recording disc. The servo system includes circuitry for detecting when the light beam traverses a switching line, which, in the illustrative embodiment, is the track centerline, for applying a constant-magnitude acceleration force to deflect the beam to a corrected position, and for reversing the polarity of the acceleration force when the beam traverses the switching line.

Abstract: A digital servo system for maintaining a detection device, such as a reading beam, as nearly as possible centered with respect to an information track, such as an optical track on a video recording disc. In each of the embodiments disclosed, circuitry is provided to process a signal obtained from the reading beam, to obtain timing signals indicative of transitions of the beam across noncentral switching lines parallel with the track. In one embodiment, a constant-magnitude acceleration signal is applied to a beam position transducer, and is reversed in polarity each time a switching line is crossed after first crossing the centerline. In another embodiment, the polarity of the constant-magnitude acceleration signal is reversed after crossing a switching line a second time and after applying an additional acceleration impulse of relatively short duration.

Abstract: A record carrier is described on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas. By giving the information tracks periodic excursions towards and away from adjacent tracks, in a direction transverse to the direction of reading, the period of the excursions being substantially greater than the average period of the areas and the amplitude of the excursions being smaller than the width of the tracks, a control signal for centering the read beam of radiation on an information track can be obtained without the use of additional optical means. The excursions of the tracks have such relative phase that the tracks are in nested concentric relation and one component of the stored information represents the phase of the undulations.

Abstract: In order to record information spirally on a disk and to reproduce the recorded information accurately without any contact, at the recording, an information signal and a predetermined signal for synchronous detection are added together, the resultant signal is subjected to frequency modulation and, while a laser beam intensity-modulated by the frequency-modulated signal is minutely swung in the radial direction of the rotating disk at the same frequency as that of the synchronous detection signal, it is caused to impinge on the disk to thereby record the information spirally on a recording medium of the disk without any contact. During the reproduction, as the disk is being rotated, a light spot is caused to impinge along an information groove formed on the disk, and reflected light or transmitted light from the disk is detected in the form of an electric signal.

Abstract: A system for guiding a tool according to a predetermined direction includes a detector head which photoelectrically scans a line of the pattern with the line varying in width at predetermined locations and with the output signals of the scanning photoreceptors being conductable to a switching device having an adjustable switching threshold so that when the scanning is in the area of the altered line width an auxiliary signal is formed in addition to the control signal for the coordinate motors.

Abstract: The invention relates to apparatus for automatically guiding a moving object such as a vehicle along a pre-determined path, the apparatus including two detectors which are mounted in a spaced apart relationship on the object, the detectors being responsive to the intensity of electro-magnetic waves such as X-Rays emitted along the path. Comparison means for instance a dividing circuit is connected to the detectors to determine the ratios of the intensities of the magnetic waves and to provide a signal which is acted on by adjustment means that adjusts the direction of movement of the object to bring it back onto the path. The invention provides for irradiation means which is mounted on the object and which causes excitation and emission of secondary waves of pre-determined wavelength from the path.

Abstract: A method for automatically positioning a workpiece having at least one marking, specifically a wafer for integrated circuits which is to be processed in a charged-particle beam apparatus, relative to a scanning field or mask. In the method, a scanning beam scans the workpiece along the line and a marking signal is generated when the marking is reached by the beam. This marking signal controls a device which generates a control signal in response to the marking signal which is proportional to the deviation of the marking position from a reference position and which drives a device for correcting the position of the workpiece relative to the scanning field or mask.

Abstract: A laser therapy apparatus comprising a radiating source, a control system of said radiating source, which system is connected to said source, a mechanical beam shifting scanner connected to said radiating source, a unit for processing and storing information on a program of exposing biological objects to irradiation, to whose output there is connected a unit control for reading out information from said information processing and storage unit, as well as an electromechanical unit whose outputs are connected to the mechanical beam shifting scanner, said electromechanical unit having a drive by means of which directional irradiation, i.e. the beam, is focused on an object exposed to irradiation and oriented in three spatial coordinates, one output of the control and information readout unit being connected to the input of the electromechanical unit, whereas its second output is connected to the input of the radiating source control system.

Abstract: This invention relates to a system for optically playing back recorded signals from a recorded medium on which signals of images or sounds are continuously recorded so as to constitute a signal recorded line or signal track. In play-back the images or sounds are optically recognized by the width-change of the signal recorded line. A narrow light beam for the play-back is deflected at a predetermined frequency in the direction perpendicular to the signal recorded line, i.e. in the direction of the width of the signal recorded line, in order to perform the optical scanning. The narrow light beam which is reflected or transmitted on the recorded medium surface reaches photo-sensitive elements such as photo-diodes.

Abstract: A sensor for use in controlling the operation of a mobile farming machine which has an image taking means carried by the machine and adapted to take the image of a part of the field to be worked, and photoelectric converting means adapted to convert the image into electric signal. The photoelectric converting means consist of a plurality of photoelectric elements disposed in a row crossing the line of movement of the machine, so that the states of the photoelectric elements are changed as the position of a boundary involved by the image taken by the image taking means is moved. Thus, the deviation of the machine from the correct course is detected through the change of states of the photoelectric elements.

Abstract: The line-trace to be read-out is illuminated by a light spot scanning radially from, and by rotation around, a center that it set near the line-trace to be read, the radial scan having its own scan frequency and the scan turning around the center at a specific frequency of rotation. A signal is formed corresponding to the contrast modulation between the line-trace and the surrounding background, which is processed to give a signal corresponding to the minimum distance between the scan sweep center and the line-trace, the latter signal being processed further to produce the co-ordinates needed for directing the servo-control means of a machine tool.

Abstract: A method and apparatus for railroad track surveying for accurately determining track gauge includes a pair of electro-optical sensors which are situated completely above the rail head level. A collimated light source in each sensor projects a narrow light pattern containing a substantial vertical component downwardly against the gauge surface of the rail. An optical system in the sensor collects an image of the pattern and focuses it upwardly along an object axis to a focal plane. A detector in said focal plane is responsive only to that portion of the image which appears at a juncture of the focal plane with an object plane which includes said object axis and extends laterally thereof in directions parallel to the plane of the rail heads and intersects the gauge surface at a point five-eighths of an inch below the running surface when the rail head is at its nominal position.

Abstract: An optical reader for reading information recorded on a disk. The reader includes a mirror and a focussing lens. The mirror surface is alterable by feedback means to shift the point of incidence of a light beam passing through the lens onto the disk. The position of the surface is always selected to allow the light beam to pass through the image side focal point of the lens.

Abstract: A pattern tracer having provision for recognizing special markings on the pattern termed "command marks" and for recognizing at least two different kinds of commands to enable special control of the machine tool controlled by the pattern tracer.

Abstract: An electro-optical computer-controlled scanning system adapted to accurately and rapidly digitize an engineering or other line drawing and to store the digital data, making it possible to reassemble a stored drawing with virtually the same fidelity as the original document. Use is made of a laser beam scanner having a wide angle deflector to sweep the beam in the X and Y directions to a degree sufficient to traverse the X and Y dimensions of the drawing being digitized and a narrow angle deflector for sweeping the beam in the X and Y directions to a degree sufficient to examine any selected region of the drawing. Information is extracted from the drawing in a two-mode procedure, the first carrying out a low-resolution survey along a narrow stripe extending in the X direction across the drawing to determine whether any drawing information is contained therein.

Abstract: While monitoring the phase state of a material in processes including crystallization from a melt, a photo-optical system is operated to receive the radiation coming from the material being treated, and the amplitude-frequency spectrum of the output electric signal of the photoreceiver of this system is followed. The presence in this signal of a low-frequency components within a range of from 0.5 to 30 Hz indicates that the optical system is located above the molten portion of the material being treated. To utilize this method for monitoring the position of the interface between the solid and molten zones or phases, there is employed a carriage supporting thereon the photo-optical system and mounted for reciprocation transversely of the interface between the liquid and solid phases. The output of the photoreceiver of the photo-optical system is provided with a frequency-amplitude analyzer including a circuit for inhibiting the permanent component.

Abstract: A circular scanning optical pattern tracer produces two impulses per cycle, one impulse in the forward direction and one in the reverse. Means are provided to utilize either one of said impulses selectively to cause the tracer to proceed in a given direction or reverse at will in accordance with the pulse selected.

Abstract: This disclosure deals with a line or pattern following system for use with a machine including first and second motors for moving a device in first and second generally perpendicular directions. The system includes an array of light sensitive elements arranged at angularly juxtaposed positions, the array being positioned adjacent said line or pattern. An image of the line or pattern falls on the array and makes an angle .theta. with a reference point on the array. The system further includes means for sequentially scanning the outputs of the elements, and angle means responsive to said outputs and to said reference point for generating first and second signals. The first signal is a function of sin .theta. and is connected to control energization of the first motor, and the second signal is a function of cos .theta. and is connected to control energization of the second motor.

Abstract: A bi-axial scanning device for guiding a template copier for machine tools comprises a shaft carrying a scanner with a pointer at one end and adapted to assume a zero position and follow the shape of a plane profile from the zero position. A flat disc spring supports the shaft at an intermediate point for resilient pivoting. An optical device comprises a source of a calibrated light beam and a photo-detector arranged to receive the beam. Either the calibrated light beam or the photo-detector is in a fixed position and the other is displaceable with the pivoting of the shaft in response to the pointer in contact with the template, the displacement being detected by the photo-detector and producing control signals emitted from the photo-detector. An amplifier is connected to the photo-detector to receive the control signals and an outlet transmits the amplified control signals to the machine tools.

Abstract: A curve line reader of the type wherein a recording medium carrying an optically visible curve line is caused to move relatively to an electronic camera tube which electronically scans an optical image of the medium along a locus extending transversely of the recording direction to generate a video output signal containing pulses produced by the impingement of the tube scanning beam upon the curve line image is modified by the addition of a semicylindrical optical lens having a length at least equal to the transverse dimension of the recording material and arranged with its longitudinal axis lying in the plane of the scanning locus of the camera tube whereby the optical image received by the camera tube is selectively magnified in a direction parallel to the recording direction to sharpen the video output pulses generated by the curve line segments having a large directional component parallel to the scanning locus of the camera tube.

Abstract: An analog of a path through which a cross slide table, for example carrying a workpiece or a tool is to be moved is traced on a drawing sheet. At points of change of direction or commanded speed of movement, graphic machine-readable symbols are placed on the drawing. A sensor, with sensing elements located in the quadrants of an x-y coordinate system, preferably secured to the cross slide itself, is placed above the graphic drawn representation of the movement path, the graphic representation is introduced by means of a program carrier beneath the cross slide and, upon recognition of symbols representing change of direction, speed of movement, suitable signals are derived which control servo motors moving the cross slide and the sensor in accordance with the sensed signals picked up by the sensor from the graphic representation of the movement immediately beneath the cross slide table itself, thus avoiding the necessity of numerical or other programmed input to the cross slide.

Abstract: An apparatus for determining the relative position and orientation of an object by automatic equipment. The objects are transported in a first movement direction on a translucent conveyor belt. A line array of photodiodes is arranged transversely to the belt. The electrical condition of these diodes is scanned in synchronism with the movement of the belt. The extreme signals in the longitudinal and the transverse direction of the belt indicate the tangent points of two sets of mutually parallel, but transverse relative to each other, tangent to the objects. The relative positions of the points are compared with a stored system of coordinates for regularly spaced orientation directions of the objects. The closest correspondence matches the orientation and position of the object. Thus, it is not necessary to memorize each position of objects in an object handling or similar apparatus, so that control processing is simplified.

Abstract: A highway line detection system for an automobile which provides an output signal when a traffic line on a pavement under an automobile is about to be crossed. It includes a photoelectric sensor connected to an electrical bridge circuit, and the bridge circuit includes an impedance element which is varied in impedance responsive to the integrated output of the bridge circuit, and thereby the bridge circuit is maintained in balance for ambient light conditions. Further, the threshold of detection of the system, at which point an alarm is sounded, is varied as a function of the ambient light state, whereby the sensitivity of the system is increased for low light conditions and decreased for high light conditions to compensate for an opposite characteristic of the photosensor.

Abstract: An optical scanning device which scans a rotary video disc with the aid of a light beam comprises an objective which performs focussing movements, for focussing a light spot on a recording surface of the video disc, as well as tilting tracking movements and time-error correction movements. Near its lower end the objective is suspended in an impregnated corrugated loudspeaker diaphragm of fabric fibre which enables the various movements of the objective to be made without giving rise to annoying resonant effects. The tracking movements and the time-error correction movements are obtained with the aid of coils which are connected to the objective near the upper end and which are disposed in air gaps of associated permanent magnetic stators.

Abstract: An automatic lawn mower operable to cut about the periphery of a lawn, moving inwardly, and automatically shutting off at the conclusion of the cutting operation. A cut border is placed about the periphery of the lawn to be mowed and also about any obstacles within the area. The mower utilizes an array of light sensitive resistors and a columnized light source to detect the transition between cut and uncut grass in order to track in an irregularly shaped spiral to the center of the lawn. A portion of the sensor system provides for proper guidance of the mower around the cut perimeter of any obstacles in the cutting area. The mower may utilize an array of light sensitive resistors, a columnized light source and actuated light reflectors to detect the transition between cut and uncut grass in order to track in an irregularly shaped spiral to the center of the lawn.

Abstract: A curve-following device having an optical sensing head which senses a guide zone containing the guide line to be followed and having at least a substantial transverse component, and which is movable along the guide zone at a substantially slower speed than the sensing rate and is connected to a control instrument which forms, from the signals delivered by the sensing head, control signals for the movement of the sensing head along the guide line. Marks associated with the guide line and detectable by the sensing head are detected for tripping further control commmands. At least one separate code zone which is sensed separately from the guide zone is provided at the side of the guide zone.

Abstract: This application relates to circular scanning line tracers or edge tracers and has particular reference to means for producing adjustable lead. In tracing apparatus having a circular scan, the scanner scans in advance of the point of rotation of the tracing mechanism by an amount referred to as the lead. This lead ideally varies depending on the tracing velocity. It is proposed to apply a vari-focal lens to the optics to provide a scanning circle of adjustable diameter to vary the lead.

Abstract: A system incorporating a photosensitive device and associated circuitry for scanning a line to be traced.