Abstract: A method for generating mask transparencies for the mass production of printed circuit boards using a laser photoplotting system includes an algorithm for mapping geometric entities from the continuous plane such as is used in vector photoplotting to a pixel graphic representation of the geometric entities. The method reduces offset errors between rectangular entities and circular entities in phototool primitives constructed in the discrete pixel graphic system by selecting a pixel to represent the corner of the rectangular entity that is closest to the circumference of the circular entity.

Abstract: A pick and place machine has two pairs of centering jaws slidably mounted in rectilinear slots of a shift plate, with each jaw pair being driven by a pair of scissor links respectively pivoted to a pair of nuts mounted on a dual reverse threaded shaft.

Abstract: A cathode ray tube with a fiber optic faceplate is successively stepped to discrete adjoining areas of a photosensitive film upon which a pattern is to be exposed. The pattern is divided into a plurality of sections, which are exposed upon the film by the cathode ray tube one at a time at its successive positions. In each position of the cathode ray tube, its beam traces a pattern of light upon its faceplate that corresponds to one section of the overall pattern. The pattern of light traced on the faceplate is transmitted directly to the film which is in contact with the fiber optic faceplate.

Abstract: A pick-and-place machine having magnetic elements which hold down the chips at the pick stations, thus preventing shingling, and also hold such chips at the pick stations adjacent a stop element. The magnetic elements create magnetic forces in two directions relative to chip elements having magnetizable terminal portions. The magnetic elements are provided in combination with feed apparatus that is adapted to stop, when the associated groove is full of chips, rather than causing the machine to jam.

Abstract: The image formed by a laser flying spot scanner on a photosensitive medium is subject to error in size and/or position because of deviation of the photosensitive surface from a nominal position. The deviation will occur if the substrate carrying the photosensitive surface does not have a uniform thickness. In a scanning system having a code mask that produces reference signals for controlling timing of writing beam modulation, compensation for the error is provided by maintaining a fixed distance between the code mask and the surface of the medium. The code mask floats freely upon the medium surface to move up and down with height variations of the surface as the medium passes under the code member and under the writing beam. Alternatively, the platen that supports the photosensitive medium is allowed to float and is continuously urged upwardly against spacing or position sensing devices to maintain the medium surface at a fixed distance from the mask.

Abstract: The precision rotatable polygonal mirror of a laser scanning system is fixed to one of a pair of spaced flanges of a rotatable shaft, and has one surface supported upon a fixed air bearing. A floating air bearing is formed to define a differential piston which is pressurized to load the bearing and provide the desired air film bearing thicknesses. The two part thrust bearing has a net effective axial dimension that varies to significantly decrease required tolerances, to minimize moments introduced into the shaft and polygonal mirror, and to provide a more constant air bearing clearance over a larger range of air pressures.

Abstract: A laser pattern generator for making a printed circuit board master image has its control data divided into image components according to whether a component is a simple figure such as a trace 32 that readily lends itself to conventional data compression coding or a more complex pattern 35 that is less readily coded. Data describing the complex patterns are prestored in a data library 358. Scan line elements of traces and patterns are independently assembled in separate work buffers 366-372. Data in the separate work buffers are then combined, either additively or subtractively, for assembly in a line assembly buffer 374 from which a data stream is derived for modulation of the laser 10. Additively combining data from the work buffers allows one image component to be electronically overlaid upon another, whereas subtractively combining data from the work buffers enables the pattern defined by subtractive data to be removed from another pattern.

Abstract: This invention provides a feed arrangement for chips in a pick-and-place machine in which a vertical magazine feeds chips into a groove in a vibrating table, with the chips being advanced toward a pick station by a gravity actuated lever which will be stopped in the event the groove is full of chips rather than causing the machine to jam or cause damage.

Abstract: The laser beam of a flying spot scanner is turned on and off to write data under control of a reference clock that generates clock signals determined by the position of the writing beam. To detect position of the writing beam a reference beam is scanned in synchronism with the writing beam along and through a coding mask to a strip of retroreflective material fixed adjacent the mask. The reference beam is retroreflected through the mask back through the scanning optics to a fixed detector that produces an output determined by the scanning coded reference beam. Unwanted reflections from the mask surface are separated by tilting the mask. Reading of a document having a pattern of opaque and transparent areas is accomplished by retroreflecting a scanning laser reading beam from a body of retroreflective material adjacent to but spaced from one surface of the document.

Abstract: The laser beam of a flying spot scanner is turned on and off to write data under control of a reference clock that generates clock signals determined by the position of the writing beam. To detect position of the writing beam a reference beam is scanned in synchronism with the writing beam along and through a coding mask to a strip of retroreflective material fixed adjacent the mask. The reference beam is retroreflected through the mask back through the scanning optics to a fixed detector that produces an output determined by the scanning coded reference beam. Unwanted reflections from the mask surface are separated by tilting the mask.

Abstract: This invention provides an air bearing system for guiding along one of two opposed walls by a piston-mounted air bearing. A second piston-mounted air bearing is adjacent the other of the opposed walls, having a larger piston to exert a greater force and cause the first piston to bottom against a stop. The bearings receive air pressure along their inner surfaces for balancing the load on them and avoiding distortion.

Abstract: This invention provides an electric motor for high speed operation that includes an inner housing assembly made up of two members having tubular walls having telescoped sections bonded together at the central portion of the assembly, with the field of motor bonded to the inside of the two inner housing members. The opposite ends of the inner housing assembly then are bored to provide precisely aligned bearing support surfaces. Ball bearings fit on these surfaces and rotatably mount the armature. An outer housing fits around the inner housing and is spaced from it, providing an unobstructed annular passageway for circulating coolant. The passageway includes inwardly directed portions around the bearings for efficient removal of heat from those areas.

Abstract: A method and related apparatus for finding center lines or center points of distinguishable areas in a scanned field, such as the field of view of an optical scanning device in which is positioned an integrated-circuit chip. The invention is disclosed in the form of circuitry for analyzing a serial digital data stream representative of the image of the scanned field, and for determining the positions of center lines of center points of distinguishable areas in the field falling within a selected size range. The circuitry includes separate sections for analyzing the scanned image in order to detect center lines with respect to four separate scanning directions, the outputs of these sections being synchronized with each other, although delayed from the original serial data stream, and being representative of center lines of areas falling within the selected size range.

Abstract: This invention provides a frictional clamping arrangement for holding the workpiece being cut by a router so as to prevent movement of the cutout portion of the workpiece in the last increment of the cut. The device includes a pressure foot having a clamping member which is forced downwardly against the surface of the workpiece when the cut is nearly completed for holding the cutout portion of the workpiece motionless relative to the worktable so as to prevent its lateral movement during completion of the cut. The clamping member is fixed relative to the spindle during the principal part of the cut, but is released for limited movement relative to the spindle when holding the workpiece.

Abstract: This invention provides a drill changing device for a drilling machine in which a collar is provided on the shank of a drill at a predetermined location relative to the tip of the drill, the collar being frictionally gripped by a split sleeve so that the shank projects outwardly from the sleeve, the sleeve being slidable relative to a fixed support and normally biased against a shoulder on the support, allowing overtravel when the collet of a drilling machine engages the collar and receives the shank. The tip of the drill is at a predetermined position relative to the collet when the collet engages the collar so that the drill will effect proper penetration of the workpiece in a drilling operation.