Abstract: A device for detecting the marginal edge or a marking of a material web. The device contains an optical sensor and two light sources associated with the optical sensor. The first light source emits directed light beams and aims such beams at the material web. The first light source is formed by a plurality of light-emitting diodes, arranged such that the light reflected by the material web in a diffused manner cannot be detected by the optical sensor. A second light source is also associated with the optical sensor. The second light source contains a diffuser disk. The diffuser disk generates diffused light that is emitted in all three-dimensional directions. When the second light source is active, the condition of reflection is satisfied so that it is possible to scan the material web having mirror-like reflection.

Abstract: Automated methods and systems for analyzing data associated with an industrial process parse data entries received from devices in an industrial process, such as a mail or paper processing system. The parsing can include applying state machines to the data to identify events and produce output relating to the process for which the data is being analyzed. Statistical measures are computed for the output from each of the state machines. The statistical measures are compared to design limits. Output is displayed to the user in a format that facilitates interpretation of the data.

Abstract: An embodiment of the present invention comprises a method and apparatus of detecting edges. Light directed from any angle at a smooth surface will not cast a shadow regardless of the printing on the surface. Light cast at an appropriate angle on a stepped surface casts a shadow. The apparatus and method of the present invention cast light from several directions/sources while focusing on one location. If the same level of gray is detected from all sources, there is no shadow and hence the location is not an edge. If the result of one or more of the light sources is a darker image than the others, there is indication of an edge by the presence of a shadow. The use of edge detection in an insertion machine can help to decrease the amount of user adjustment needed to operate the machine using various sizes of envelopes.

Abstract: A wafer prealignment apparatus comprising a CCD linear sensor and a wafer prealignment method which facilitate the sensing of wafer presence, improvement in precision of position sensing, and edge sensing adapted to the material of the wafer even of the material is transparent or not. A photodiode (27) is provided in a vicinity of the first pixel from the center shaft of the wafer rotation means of a CCD linear sensor (5) to detect a wafer (1) on the basis of the luminous energy value. The time from the issuance of a measurement command to the sensor (5) to that of an ROG signal for transmitting the detection timing of the sensor (5) is measured to correct the angular error of a measurement position due to the rotation during this measurement. For sensing an edge position of the wafer (1), the scan start point of the sensor (5) is set on the opposite side of the center shaft of the wafer rotation means. When the wafer is transparent a sense signal is binarized to set its change point as the edge position.

Abstract: A testing device is used to establish the position of a notch or bump on a disk. The testing device has: a testing area for positioning at least one disk having an edge with a notch or bump; a light source for illuminating the edge of the disk; a first light sensor for receiving light of the light source reflected by the edge of the disk; a second light sensor for receiving light of the light source reflected by the notch or bump of the disk, if the notch or bump is located within a predetermined positional area; and an assessment unit for establishing, based on the light falling onto the first light sensor, whether a disk is positioned in the testing area and for establishing based on the light falling onto the second light sensor whether the notch or bump is located within the predetermined position.

Abstract: A laser inspection apparatus has a light source 13 for outputting laser beam, application means 5, 33, 34 for irradiating the laser beam 7 output from the light source 13 to any desired position of a detected body 21, first detection means 2 for detecting fluorescence 8 generated from the detected body 21 to which the laser beam 7 is applied, and second detection means 3 for detecting reflected light 8 scattered on a surface of the detected body 21 to which the laser beam 7 is applied.

Abstract: A notch or flat sensor for a semiconductor wafer on a wafer stage or support includes a dual photodiode detector arrangement located at the edge position of the wafer. Each photodiode element has substantially equal coverage of the wafer edge when the wafer's notch or flat is not proximate to the detector, but has different coverage from the other photodiode when the notch or flat is proximate to the detector. A light source illuminates the edge of the wafer opposite the detector arrangement. Comparison of the light intensity sensed by each photodiode, e.g. by means of a differential amplifier circuit and threshold sensor, reveals the position of the notch or flat.

Abstract: Apparatus and method for precise detection of a leading edge of an object, such as printing plate. The printing plate penetrates a gap between a light source and a sensor. Detection is made when the amplified signal equals the peak signal divided by N, meaning 1/N of the sensor is covered by the plate.

Abstract: A substrate detection sensor is operatively connected to a door moving mechanism for opening/closing a front door with respect to a sealed container accommodating therein a plurality of substrates. The substrate detection sensor enters the sealed container and detects the substrates successively as it is lowered integrally with the front door, and retracts from the sealed container when all of the substrates have been detected.

Abstract: A sensor system for determining the position of an edge of a moving web of material travelling along a predetermined travel path. the sensor system comprising a transmitter/receiver assembly, a beam reflector assembly and sensor signal processing. The transmitter/receiver assembly is positioned adjacent to the travel path of the moving web of material. The transmitter/receiver assembly has a transmitter transmitting a light curtain across at least a portion of the travel path, and a receiver receiving a shifted light curtain transmitted across at least a portion of the travel path and generating video output signals indicative of the position of the edge of the moving web of material. The beam reflector assembly is also positioned adjacent to the travel path of the moving web of material such that the travel path passes between the transmitter/receiver assembly and the beam reflector assembly.

Abstract: A reference medium is scanned both with a medium sensor (44) capable of detecting a low-transmittance printing medium with high accuracy and with a medium sensor (45) capable of detecting a high-transmittance medium with low accuracy so as to find edge positions Ry0, Ry1 of the reference medium. The difference Diff0 between the edge positions is calculated and stored as a correction value. If it is hard to detect a printing medium by means of the medium sensor (44), the medium sensor (45) is used to detect the medium, and the resulting edge position is corrected using the correction value Diff0. In addition, for any given printing medium, a first driving level of a light source for outputting a predetermined output amount of the sensor (44) and a second driving level of a light source for outputting a predetermined output amount of the sensor (45) are calculated and, based on the difference between the two driving levels, the type of the printing medium is determined.

Abstract: A reflection type sensor includes a light emitting element emitting light to an object and including a plurality of LED chips disposed to be adjacent to each other and integrated into a package, and the LED chips emit light beams belonging to different wave bands. A light detecting element detects the light reflected on the object, and performs a photoelectric conversion for the light beams belonging to the different wave bands, thereby delivering a light signal. A light detecting circuit determines the presence or absence of the object on the basis of the light signal delivered from the light detecting element.

Abstract: A method of detecting an edge of an object, including the steps of lighting, in each one of a plurality of different directions, at least a portion of the object, taking an image of the portion of the object and a vicinity of the portion which are lighted in the each one of the different directions, synthesizing the respective images of the portion of the object taken by lighting the portion in the different directions, and detecting, based on the synthesized images, an edge of the portion of the object.

Abstract: A dual beam concentric polar axis scanning machine for allowing flat parts to be easily scanned and measured. Flat shaped parts are placed on a glass datum type part support surface. The dual beam laser type scanners are positioned on a motion stage beneath the part support surface and move in the x and y planes parallel to the part support surface. Detectors above the surface receive the beams and move in unison with the scanners. Initially, the beams trace the external outline of the part and measure all grooves, side indentations and the like. Next, the beams pass over the surface of the part locating and mapping the locations of any openings therethrough. Finally, the beams trace perimeter edges of each of the openings for their measurements.

Abstract: A device for detecting a web, the device including a light source adapted to emit light generally in the direction of the web; a lens spaced apart from the light source and adapted to receive light originating from the light source, the lens having a radial index of refraction gradient; and an image sensor aligned with the lens, the image sensor adapted to receive light from the lens and to convert the light to a signal. Also, a method for detecting a web, the method including emitting light from a light source; capturing light reflected by the web with a lens having a radial index of refraction gradient; focusing the captured light on an image sensor; and converting the focused light to a signal. Also, a method for aligning two webs, wherein each web has a position, and a method for detecting an object.

Abstract: The invention relates to a device for detecting the location of an edge (2) of a transparent, anisotropic material (3, 3′) comprising at least one sensor (1) with a light source (4), two polarization filters (6,7) with transmission axes (8,9) meeting at a 90° angle as well as a light detector (10), whereby the light source (4) and one polarization filter (6) are located on one side of the edge (2) to be detected and the second polarization filter (7) and the light detector are located on the other side.

Abstract: A method and system for guiding a web of moving material is disclosed. The system includes a plurality of variable light sources that can project light onto the surface of the web. One light source or a combination of light sources can be selected to project light onto the web, and the wavelength of the light can be selected. A light detector receives light reflected from the surface of the web and generates a data signal in response to the light received. A controller can be used to analyze the reflected light to determine the position of the web of moving material. The system enables the lateral and/or longitudinal position of various types of webs to be efficiently and effectively determined based upon the position of a line, edge, or other mark disposed on the surface of the web.

Abstract: The mapping sensor system of the invention is intended for use with a mechanical arm of an industrial robot which loads and unloads flat circular objects, such as semiconductor wafers, into and from wafer cassettes on operations of processing the semiconductor wafers in stand-alone or cluster machines used in semiconductor production. The mapping system consists of a light source, a light-receiving element, and a light beam shaper. The light source is installed on the front end of the robot arm and directs the light via the beam shaper to the leading edge of the semiconductor wafer. The beam reflected from the wafer edge is sensed by a light-receiving element, such as a photodiode. The shaper modifies the shape and the cross-section of the beam directed towards the wafer so as to provide reflection from the curvilinear surface of the edge, irrespective of the existence of the notch, most optimum for detection by the photodiodes and without generation of false signals.

Abstract: A method and apparatus is disclosed to precisely locate an edge of an imageable plate mounted on a drum or other support surface. A light source and light sensor are used to measure the difference in reflectivity between the plate and the support surface. The drum or support surface contains at least one groove to increase the difference in reflectivity between the plate and the support surface. The groove may also contain an anti-reflecting layer to further increase the difference in reflectivity. The groove may also have a geometric shape that causes incident light to be directed away from the light sensor.

Abstract: In an optical device having an objective lens for magnifying an image of a target object and a focusing unit including a laser source for irradiating the target object through the objective lens and a focus detecting light-receiving section for receiving light reflected from the target object, positions in the periphery of the target object are detected by using the laser beam emitted from the laser source of the focusing unit while changing a relative positional relationship between the target object and the objective lens.

Abstract: An edge detector with sub-micron accuracy. The edge detector comprises two single mode optical fibers with an optical path between them. One fiber is coupled to a laser light source, and creates a light beam. The other fiber is coupled to an optical power detector. The optical power reaching the optical power detector is determined by how much of the light beam is obscured by an object. Thus the position of the edge of the object may be determined from the optical power measured by the detector. The edge of an object may be positioned automatically according to the optical power measured by the detector.

Abstract: A method and device for detecting the position of a transparent conveyor belt including directing light beams (2) onto the region of an edge (3) of the conveyor belt, detecting a jump in intensity of the light beam (2, 2′) as a consequence of the partial insertion of the conveyor belt into the beam path (2) and evaluating the detected jump in intensity in order to determine the position of the conveyor belt, wherein the light beams (2) are linear polarized light and the beam path (2) is directed at an angle or irradiation (&agr;) between 40° and 80° of the light (2) onto the bounding surface (7) in such a way that a high degree of reflection is achieved and reflected light and non-reflected light is detected.

Abstract: A device for exposure of the peripheral area of a film circuit board in which the edge of the copper foil can be exactly determined and the position of the irradiation area can be controlled with high precision is obtained in that a resist (R) in the peripheral area of a conductive foil located on a film circuit board (TP) is irradiated with exposure light and is thus exposed, while the film circuit board (TP) in which there are perforation holes (PH) with a stipulated pitch to one another, is transported, in that an optical detector (4) is used as the sensor for determining the edge part of the conductive foil, in that the sensor light emitted onto the edge part of the conductive foil is received by a light receiving part (4b), in that the optical detector (4b) is subjected to motion control in the direction which orthogonally intersects the transport direction, such that the amount of light reception is constant and in that the area irradiated with the exposure light is moved by the same amount as the optic

Abstract: The present invention describes systems and methods for exposure and removal of material on the periphery of a substrate. The system includes an emitting radiation or exposure source, preferably a guide such as an optical assembly and an emitter, an edge detector, a transport, which comprise rotating and radial mechanisms, and a substrate support. The optical assembly directs radiation from the exposure source to the wafer or emitter. The transport supports the emitter and the edge detector about the substrate, and a tracking exposure head preferably supports the emitter and edge detector. As the emitter moves along the periphery of the substrate, the edge detector sends signals to control systems, which process signals, and command the transport to adjust the position of the emitter when necessary to expose the periphery of the substrate. In another embodiment, the system provides an exposure source chamber, a process chamber, and optionally a control chamber to isolate particle and thermal problems.

Abstract: A wire analyzing device includes a source of radiation that irradiates a plurality of sensing elements. The source of radiation preferably is a laser beam and the sensing elements preferably are light sensitive devices that each provide an individual output indicating the amount of radiation incident on each sensing element. A wire sample is moved near the sensing elements so that it interrupts the radiation received by each sensing element. The output of each sensing element is utilized to determine any one or more of a number of desired characteristics of the wire sample. Example characteristics include the length and condition of an exposed, conductive portion of the wire, a position of an insulation shoulder, a position, orientation and condition of a seal member placed onto the wire.

Abstract: This invention uses the pattern-based signal to accelerate the evaluation process as a means to replace complicated computing procedures. This invention is constructed through implementing absolute coordinates to produce pattern-based signals by position and two optical sensor signals, and through conducting the feature extraction process. This process produces feature signals of sidelong and overlapped issues. Furthermore, through transforming signals, feature signals can be handled by the digital data processor. Thus, this invention can achieve the three main objectives of wafer mapping.

Abstract: A method and apparatus for the detection of an edge of an object, with at least two photoelectric barriers, having at least one sender and at least one receiver apparatus as well as at least one common evaluation electronic unit for the detection of the edge or the presence of the object found on a transparent transporting belt. A diaphragm apparatus creates specially shaped light beam cross sections, wherein at least one light beam (B) is irradiated as a sufficiently narrow slit (5) in the direction of the edge to be detected, wherein the signals of the photoelectric barriers (3,4,10,11,12,13,14) are logically interconnected in the common evaluation unit (8).

Abstract: A semiconductor device lead inspection apparatus and method are provided for capturing images of the semiconductor edges and leads along two optical axes which have different directions in a plane perpendicular to the semiconductor device edge. A first image is reflected off an optical surface of a prism to a direction corresponding to the camera optical axis. A second image is reflected by two optical surfaces of the prism to a direction corresponding to the camera optical axis.

Abstract: A disk-shaped object detecting system detecting the presence or absence and position of a disk-shaped object such as semiconductor wafers or magnetic disks includes a light emitting element emitting light toward a circumferential edge of the object while being moved across the object, a light receiving element receiving the light reflected on the circumferential edge of the object while being moved across the object together with the light emitting element, delivering first and second light signals each according to the received light, the first and second light signals having a ratio depending upon at what position between opposite ends the light receiving element receives the light reflected on the circumferential edge of the object, the first and second signals having a magnitude relation which is reversed when the light reflected on the circumferential edge of the object has been moved from one end side to the other end side of the light receiving element, an AND processing section supplied with the first

Abstract: A device and a method for detecting and distinguishing between shelf-forming supports in cassettes and disk-shaped objects deposited thereon are provided for increasing accuracy in the determination of the position of shelves and objects as well as reliability of detection in distinguishing between cassette types without a disruptive influence being exerted on the objects by the inserted protective supports. The objects and different types of supports for the objects which are distinguished through an offset arrangement in the measurement plane pass through measurement beam bundles with their end sides, wherein each of the measurement beam bundles is situated in the region of only one type of support. The extension of the end sides of the supports in the measurement plane is completely detected by the measurement beam bundle. The device is used for the fabrication of integrated circuits.

Abstract: A sensor and detection system is included. The sensor includes at least one transmitter which has associated optical elements for emitting at least one light beam toward the object to be detected. At least one receiver is positioned adjacent the transmitter for receiving light reflected from an edge of the object. The receiver generates a signal responsive to the reflected light. The associated optical elements of the transmitter include a converging lens for emitting a focused light beam in one plane, and a cylindrical lens for emitting a diverging light beam in another plane, such that a portion of the reflected light is diverging and is received by the receiver over a wide angle of coverage.

Abstract: This invention relates to a method and apparatus for collecting or collimating light for detection. More particularly, the invention is directed to a technique for detecting the edge of an object using an apparatus having a plurality barriers or shield structures that are advantageously aligned with an optical sensor array to collect or spatially filter generated light for improved detection of the light. The invention also relates to methods of forming the structure. Application of the invention is found in the field of detecting edges of objects such as sheets of paper that are fed through imaging devices along a paper path.

Abstract: A printing apparatus places multiple images on a sheet, either by re-feeding the sheet through a duplex path back to a marking device, or by feeding the sheet to successive marking devices. An edge position detector upstream of the marking device determines the location of the sheet so that an image may be precisely placed on the sheet. The system ensures that images on both sides of a sheet are in registration with each other.

Abstract: A cable to be tested includes an electric conductor and insulation. A sleeve is fitted on the insulation. The exposed cable end is prepared for a crimped connection, the electric conductor being connected of a conductor crimp, and the insulation and the sleeve being connected by an insulation crimp to a contact. The dimensions of the conductor crimp zone and the insulation crimp zone of the contact determine the spacing of the insulation end from the conductor end, and the spacing of the sleeve end from the insulation end. To test the sleeve position, the cable is moved over a diaphragm, the diaphragm being more or less covered depending on the instantaneous edge structure of the cable, and the light quantity transiting the diaphragm varying depending on the edge structure of the cable. The edge structures of the cable can be determined from the transiting light quantity.

Abstract: A module (28) for sensing the edges of a banknote as it passes through the module. The module consists of an array of LEDs (32) optically coupled to a light diffusing element (36) past which the banknote moves. A CCD array (40) has photoelectric conversion elements coupled to the path in which the banknote moves by a self-focusing fiber-optic lens array (38). The CCD array consists of four segments (42,44,46,48) having individual shift registers which are read out in parallel, and converted to digital signals by a number of comparators (56). The comparators compare the CCD pixel output with individual threshold levels which are stored in a digital memory (54). The pixel threshold levels are converted to an analog signal for comparison with the CCD output signals by digital to analog converters (54). The digital data streams produced are divided into series of data which are analyzed to determine the presence of an optical transition in the corresponding pixel series of the CCD arrays.

Abstract: A sensor system for determining the position of an edge of a moving web of material travelling along a predetermined travel path. the sensor system comprising a transmitter/receiver assembly, a beam reflector assembly and sensor signal processing. The transmitter/receiver assembly is positioned adjacent to the travel path of the moving web of material. The transmitter/receiver assembly has a transmitter transmitting a light curtain across at least a portion of the travel path, and a receiver receiving a shifted light curtain transmitted across at least a portion of the travel path and generating video output signals indicative of the position of the edge of the moving web of material. The beam reflector assembly is also positioned adjacent to the travel path of the moving web of material such that the travel path passes between the transmitter/receiver assembly and the beam reflector assembly.

Abstract: A method for detecting the position of the edge of a moving material web by contactlessly scanning the material web with a row of sensors. The sensors generate signals that are filed in a storage unit. A turning point is determined based on the function of the signals received from the sensor locations, and is issued as the edge position.

Abstract: Apparatus for the measurement of position of an object in a given direction, comprising: a one-dimensional array of light detectors, comprising a plurality of detectors including at least three detectors, each of which produces a signal at a given position in response to light reaching the detector; at least one edge between a dark and a light area viewed by at least one of the plurality of the detectors, which the at least one edge moves, in relation to the plurality of detectors, as the object moves in the given directions; and computing circuitry which receives signals from the at least one detector viewing the at least one edge and determines the position responsive to the signals produced by the at least one detector at the given position.

Abstract: For the detection of—or for the determination of the position of edges (K) of objects (G), a light source/sensor device arrangement in the manner of a light barrier is utilized, in which the light beam generated by the light source (12) is focussed to a light line (10) in an object plane (O). Foreseen furthermore are devices for the generation of a relative movement between the light beam and edges (K) to be detected or objects (G), in such a manner, that edges (K) to be detected are moved in the object plane (O) and in doing so are aligned parallel to the light line (10). In particular for the detection of edges (K) of transparent objects (G), sensor devices (11.1-11.3) in a receiving zone (B) are equipped in such a manner, that they measure not only light intensities in the area of the axis (A) of the light beam, but also intensities of light, which is deflected from the light beam by an edge (K) in the object plane (O) positioned transverse to the light line (10).

Abstract: A measuring device for measuring structures on a transparent substrate includes an incident-light illuminating device, an imaging device, and a detector device for the imaged structures and a measuring stage for receiving the substrate. The stage is displaceable in an interferometrically measurable fashion perpendicularly to and relative to an optical axis of the imaging device. The measuring stage is designed as an open frame with a receiving edge for the substrate. A transmitted-light illuminating device is provided beneath the measuring stage. The optical axis of the transmitted light illuminating device is aligned with that of the incident-light illuminating device.

Abstract: A sensor system for determining the position of at least one edge of a web of material traveling along a predetermined path. The sensor system has a transmitter assembly capable of selectively transmitting at least one collimated light curtain and a receiver assembly capable of generating output signals in response to receiving portions of the collimated light curtain transmitted by the transmitter assembly. The receiver assembly is spaced a distance from the transmitter assembly so as to define a travel path therebetween whereby at least a portion of the web of material traveling along a predetermined travel path blocks at least a portion of the collimated light curtain transmitted by the transmitter assembly. The output signal generated by the receiver assembly is indicative of the position of the web of material as the same is moved along the travel path between the transmitter assembly and the receiver assembly.

Abstract: A method of detecting an edge of an object, including the steps of lighting, in each one of a plurality of different directions, at least a portion of the object, taking an image of the portion of the object and a vicinity of the portion which are lighted in the each one of the different directions, synthesizing the respective images of the portion of the object taken by lighting the portion in the different directions, and detecting, based on the synthesized images, an edge of the portion of the object.

Abstract: A method is used for imaging applications so that one can simultaneously apply multiple illumination schemes and simultaneously acquire the images, each associated with one of the multiple illumination schemes. The illumination schemes can be, but not limited to, any combination of reflective illumination, transmitive illumination (backlighting), bright field illumination, dark field illumination, diffused illumination, cloudy-day illumination, and structured illumination. The radiation can be in any wavelengths, ranging from sonic waves, ultra sound, radio waves, microwaves, infrared, near infrared, visible light, ultra violet, X-rays, and gamma rays. The radiation of each of the illumination schemes used in an imaging application is modulated, that is, affixed with a unique signature. One or more imaging devices can be used to collect the radiating rays simultaneously after the rays interact with the object(s).

Abstract: A sensor system for determining the position of at least one edge of a web of material traveling along a predetermined path. The sensor system has a transmitter assembly capable of selectively transmitting at least one collimated light curtain and a receiver assembly capable of generating output signals in response to receiving portions of the collimated light curtain transmitted by the transmitter assembly. The receiver assembly is spaced a distance from the transmitter assembly so as to define a travel path therebetween whereby at least a portion of the web of material traveling along a predetermined travel path blocks at least a portion of the collimated light curtain transmitted by the transmitter assembly. The output signal generated by the receiver assembly is indicative of the position of the web of material as the same is moved along the travel path between the transmitter assembly and the receiver assembly.

Abstract: When a vehicle traveling ahead of another vehicle and a reflector on a road exist laterally adjacent each other, signals indicative of reception levels of waves reflected from the objects are added together for every beam to carry out the detection of the target. The preceding vehicle and the reflector are detected in an integrally merged form because the wave reflected from the reflector is strong. Therefore, in a region influenced by the wave reflected from the reflector, only the reflector is detected without addition of the signals indicative of reception levels of the reflected waves for every beam. In a region which is not influenced by the wave reflected from the reflector, the preceding vehicle is detected by adding the signals of the reflected waves together. Thus, the reflector and the preceding vehicle can be detected in a discriminating manner.

Abstract: A position detecting apparatus for a semiconductor wafer includes a wafer worktable supported by an X-Y stage. The worktable is rotatable about an axis on a reference center for positioning the wafer. The apparatus also includes a photoelectric sensor arranged to correspond to the edge region of the wafer on the worktable. The photoelectric sensor includes an infrared-ray emitting LED and a collimator lens for applying a parallel luminous flux to the wafer edge region, and a photo diode facing the collimator lens through the wafer edge region, all arranged on the optical axis. The photo diode outputs a signal having a level corresponding to a received light quantity. The photoelectric sensor also includes a light shielding slit plate having a slit arranged on the optical axis.

Abstract: A module (28) for sensing the edges of a banknote as it passes through the module. The module consists of an array of LEDs (32) optically coupled to a light diffusing element (36) past which the banknote moves. A CCD array (40) has photoelectric conversion elements coupled to the path in which the banknote moves by a self-focusing fibre-optic lens array (38). The CCD array consists of four segments (42,44,46,48) having individual shift registers which are read out in parallel, and converted to digital signals by a number of comparators (56). The comparators compare the CCD pixel output with individual threshold levels which are stored in a digital memory (54). The pixel threshold levels are converted to an analog signal for comparison with the CCD output signals by digital to analog converters (54). The digital data streams produced are divided into series of data which are analysed to determine the presence of an optical transition in the corresponding pixel series of the CCD arrays.

Abstract: A sensor system for determining the position of at least one edge of a web of material traveling along a predetermined path. The sensor system has a transmitter assembly capable of selectively transmitting at least one collimated light curtain and a receiver assembly capable of generating output signals in response to receiving portions of the collimated light curtain transmitted by the transmitter assembly. The receiver assembly is spaced a distance from the transmitter assembly so as to define a travel path therebetween whereby at least a portion of the web of material traveling along a predetermined travel path blocks at least a portion of the collimated light curtain transmitted by the transmitter assembly. The output signal generated by the receiver assembly is indicative of the position of the web of material as the same is moved along the travel path between the transmitter assembly and the receiver assembly.