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: The present invention provides an autofocus system for an imaging system, such as an external drum platesetter. The autofocus system automatically focuses each of a plurality of scan lines produced by an imaging system on a supply of recording material, and includes a control loop with scan line to scan line feedforward of a motor command waveform.

Abstract: The present invention provides an autofocus system for an imaging system, such as an external drum platesetter. The autofocus system automatically focuses each of a plurality of scan lines produced by an imaging system on a supply of recording material, and includes a control loop with scan line to scan line feedforward of a motor command waveform.

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: An imaging system is provided for imaging media of while supported at an imaging position on a support surfaces. The system includes a loading device configured to move the medium to be imaged along the support surface to the imaging position. During loading, the leading edge of the medium, which extends across the medium width and substantially perpendicular to a direction of movement of the medium, moves in a direction towards a registration device. A registration device is contacted by the leading edge of the medium during loading so as to position the medium in the imaging position on the support surface. A medium securing device secures the medium to the support surface and a perforation mechanism subsequently punches or notches the medium prior to imaging. A drive mechanism is provided to move the perforation mechanism and the registration device, typically prior to loading of the medium, to a position which corresponds to the particular width of the medium to be imaged.

Abstract: The present invention eliminates artifacts in an image formed using a plurality of imaging sources. Visible seams in the image are eliminated by randomizing the stitch point between the scan lines produced by each imaging source. The randomization may be optimized by additionally applying a method for relocating the random stitch point based on the data content of the scan line, adjacent scan lines, and other criteria. The present invention further compensates for in-scan and cross-scan errors caused by thermally induced errors, spinner synchronization errors, mechanical misalignment, and other factors associated with the use of a plurality of imaging systems. A photodetector system, comprising a mask having a pair of triangular openings, provides measurements of the in-scan and cross-scan errors.

Abstract: A laser beam intensity modulation system has a variable delay circuit that is used to control the relative delay in the delivery of a video signal between two cascaded AOM's. This delay circuit is controlled by a delay controller that monitors the intensity modulation of the laser beam to provide feedback control. This system maximizes the rise and fall times of the beam to generate precise beam modulation required for high speed image setters.

Abstract: An imaging system is provided for imaging media of differing widths while supported at an imaging position on a support surfaces. The system includes a loading device configured to move the medium to be imaged along the support surface to the imaging position. During loading, the leading edge of the medium, which extends across the medium width and substantially perpendicular to a direction of movement of the medium, moves in a direction towards a registration device. The registration device is contacted by the leading edge of the medium during loading so as to position the medium in the imaging position on the support surface. A drive mechanism is provided to move the regristration pin, typically prior to loading of the medium, to a position which corresponds to the particular width of the medium to be imaged.

Abstract: A system for scanning a surface includes a radiation emitter configured to emit at least one beam of radiation, and a rotating deflector for deflecting the beam(s) onto a scanning surface. The deflector is movable along a translation axis to modify the path of the deflected beam(s) and thereby correct for any mispositioning of the beam(s) with respect to the scanning surface.

Abstract: A method and apparatus for driving a semiconductor laser device to produce a substantially constant optical power output over a range of temperature while preserving a high optical switching frequency.

Abstract: A logarithmic converter circuit comprises a logarithmic transfer function generating device and a transconductance amplifier connected in parallel with that logarithmic transfer function generating device, the transconductance amplifier preferrably having a transconductance in the range of about two micromhos to about twenty millimhos.

Abstract: An electrochemical sensor system includes a high impedance ion selective electrode and an electrode test circuit that has an isolation capacitor connected between the output signal lead from the ion selective electrode and a test voltage terminal, and a monitoring circuit connected to respond to the output signal from the electrode. The isolation capacitor is a high quality capacitor and provides a shunt impedance that is much higher than the maximum electrode impedance. A voltage transition at the test voltage terminal is coupled by the isolation capacitor to the output lead and the resulting decay rate of the voltage transition on the output lead is monitored to provide an indication of the quality of the electrode.

Abstract: In circuitry in which a digital circuit samples the output of an analog circuit, the improvement of using, during an interval prior to sampling, a solid-state switching element to dissipate the charge stored in a charge storage element (e.g., capacitor) in the analog circuit.

Abstract: Apparatus for measuring deflection of a light beam by sensing the beam with means providing two optical measurements, and providing an electrical output dependent upon the difference between the two measurements, with the instantaneous magnitude of each measurement being dependent upon the instantaneous deflection of the beam and upon the instantaneous intensity of the beam, the apparatus including electrical circuitry for including in the output an offset term dependent upon a scale factor and upon the instantaneous magnitude of at least one of the measurements, thereby making the offset term dependent upon the instantaneous intensity of the light beam, and means for initially zeroing the apparatus by adjusting the scale factor so as to make the output equal to a predetermined base value, whereby changes in the measurements due to changes in light beam intensity are offset by corresponding changes in the offset term, so as to thereby reduce the influence of beam intensity on the output.

Abstract: Magnetic-electronic apparatus for sensing the clearance between two ferrous metals, for application in measuring the clearance between a shear bar and the cutting knives of a harvesting farm machine, is disclosed having a magnetic sensor disposed within the shear bar for producing a magnetic field, the interception of which by the passage of a knife produces an electronic signal which is processed by appropriate circuitry for indicating the clearance between the knives and the shear bar.

Abstract: The crop discharge spout of an agricultural machine is continuously adjusted so that the crop material discharged therefrom is always directed into a wagon connected to the rear of the agricultural machine. A sensor disposed on the agricultural machine cooperates with a mechanical follower which is coupled therefrom to the wagon to provide a signal indicative of the angle between the agricultural machine and the wagon. The signal is compared with a signal from a second sensor indicative of the angle of the direction of the crop discharge from the spout with respect to the agricultural machine and an error signal is developed from the difference therebetween. The error signal is coupled to a motor which rotates the discharge spout accordingly until the error signal is reduced to zero.