Abstract: The detection of abrupt changes in opacity of a moving sheet resulting from, for example, an overlap type splice is provided. The web material is fed between two identical light emitter/detector pairs such that its opacity is measured. An abrupt change in web thickness passing through one light emitter/detector pair is sensed as a change in web opacity. The difference and resulting imbalance with the opacity signal from the other light emitter/detector pair, not yet interrupted with the abrupt change, is utilized to indicate the presence of the defect which, in this application, could be an overlap splice. The disclosed invention, although adaptable to thicker textile webs, specifically relates to a device for the detection of overlap splices in a moving sheet representative of all the paper types required by the cigarette, printing, and labeling industries.

Abstract: An optical sighting instrument having a main optical path including an objective lens, an eyepiece lens and a beamsplitter for combining or superimposing images. At least three image planes are defined with reference to the main optical path and the beamsplitter, and at least one of the three image planes is optically superimposed with the other two by the combining effect of the beamsplitter. Movable indicia elements are positioned in two of the image planes, and a fixed indicia element is positioned in the third one of the image planes. As a result, images of all three of the indicia elements are superimposed for viewing through the eyepiece lens, and the image of the fixed indicia element serves as a sighting reference. Illustratively, one of the movable indicia elements is a magnetic compass, the other of the movable indicia elements is a magnetic declination adjustment, and the fixed indicia element is a cross-hair sight.

Abstract: There is provided an optical viewing system, which is preferably a compass which eliminates the parallax and sighting problems of prior art optical systems. The compass includes a beam splitter which displays a sighted image both on a reference screen and a free-floating magnetized sphere or other moving surface. The sighted image on the reference screen and on the sphere are superimposed upon each other when viewed through one facet of the beam splitter. In this manner parallax is eliminated, thus the direction and elevation of the image may be readily and accurately determined.

Abstract: A method is provided for controlling the porosity of a web or film issuing from an electric spark perforating apparatus in accordance with an operator-set reference porosity regardless of variations in web speed, inherent web porosity, spark discharge energy and spark repetition frequency by controlling the frequencies of the electrical sparks applied to the web in accordance with the product of two signals, one a difference signal obtained by comparing the porosity of the web leaving the perforator and the reference porosity and the other signal derived from the speed of the web.

Abstract: A method and apparatus for controlling the perforation of webs being moved in a longitudinal direction, by an array of electrodes spatially distributed in a transverse direction, wherein selected control electrodes are added to or removed from the electrode array to provide a transverse, or spatial, degree of control over web porosity. Synchronized sensing of multiple point transverse web porosity, combined with logic circuitry provides the controls for selection and actuation of the appropriate control electrodes. A combined temporal and spatial porosity control embodiment is disclosed. The combined and alternate embodiments described are particularly useful for perforating paper, film, and like materials, where a high degree of area-balanced porosity control is desired.

Abstract: A system for precision perforation of moving webs employing a pulsed, fixed focus laser beam wherein the laser pulses are automatically controlled in pulse repetition frequency and in pulse width to provide a desired preset web porosity. Closed loop circuitry responsive to web speed, sensed web porosity, and a porosity preset signal provides the precise system control needed to produce and maintain the preset porosity over a wide range of system variables. The illustrative embodiment described is particularly useful for perforating paper, film, and like materials where a high degree of product uniformity and porosity control is desired.

Abstract: A method and apparatus for controlling the perforation of webs being moved in a longitudinal direction, by an array of electrodes spatially distributed in a transverse direction, wherein selected control electrodes are added to or removed from the electrode array to provide a transverse, or spatial, degree of control over web porosity. Synchronized sensing of multiple point transverse web porosity, combined with logic circuitry provides the controls for selection and actuation of the appropriate control electrodes. A combined temporal and spatial porosity control embodiment is disclosed. The combined and alternate embodiments described are particularly useful for perforating paper, film, and like materials, where a high degree of area-balanced porosity control is desired.

Abstract: A system is provided for controlling the porosity of a web or film as perforated by high intensity, coherent radiation. In particular, there is included a laser for providing at least one beam of high intensity, coherent radiation that is directed onto a web that is moved past the beam. The porosity of the web is measured and compared with an operator-set reference of porosity to control the focus of the coherent radiation, whereby the size of the resultant perforation and therefore the porosity of the web is controlled. In one embodiment of this invention, the position of a lens to focus the coherent radiation is adjusted. In a further embodiment, a support surface for receiving the web is adjusted with respect to the fixed facus laser beam to control the size of the perforation or opening created by the beam of coherent radiation.

Abstract: A system is provided for controlling the porosity of a web or film issuing from an electric spark perforating apparatus in accordance with an operator-set reference porosity regardless of variations in web speed, inherent web porosity, spark discharge energy and spark repetition frequency by controlling the frequencies of the electrical sparks applied to the web in accordance with the product of two signals, one a difference signal obtained by comparing the porosity of the web leaving the perforator and the reference porosity and the other signal derived from the speed of the web.