Abstract: A stylus for use with a digitizer tablet has a tip element that includes a front portion with a tip for engaging the surface of the tablet, and a back portion of the tip element within the stylus housing. The back portion of the tip element is adapted to apply pressure to a pressure sensitive resistance element. The front and back portions of the tip element are coupled together by a spring, in order that the tip element be resiliently compressible in the axial direction of the stylus.

Abstract: In a digitizer and method for laying out and using the tablet of the digitizer, wherein the tablet provides unambiguous binary code outputs. The digitizer may employe a cordless transducer and signal processing circuitry providing relative phase detection for determining coarse location of the transducer. An unambiguous binary code output is obtained with a grid layout which generates a set of unique binary codes, none of which is the the same or the binary inverse of any other member of the set.

Abstract: The invention disclosed herein provides a method and apparatus for counteracting the effects of a localized drag on a sheet medium as it is being moved by a drive system, for example, in a printer or plotter to prevent misregistration of the sheet medium with the X-axis drive system as the sheet medium is moved past the print or plot head which creates a drag thereon. The sheet medium is stiffened in the region thereof which is contacted by the print or plot head by bending the sheet medium in a direction normal to the direction of movement of the sheet medium. The bend may be provided by a curved guide located between the print or plot head and the X-axis drive system. Friction is reduced between the sheet medium and the curved guide by mounting the curved guide, e.g., one or more rollers, to rotate freely under the action of the sheet medium moving thereover, or by pneumatically supporting the sheet medium above the curved guide as the sheet medium is moved thereover.

Abstract: A cassette for ribbon for a printer, particularly a thermal printer, is disclosed. The cassette is configured to be stably mounted to a print carriage of a thermal printer, or to a storage turret mounted to the printer for storing a number of cassettes, and to be transferred by a passive transfer system between the print carriage and the storage turret simply in response to movement of the print carriage. A smooth, low friction path is provided for the ribbon within the cassette with no acute angle changes in the path when the cassette is in a printing position and being acted upon by the printer's print head. The cassette is provided with a brake mechanism which automatically engages the supply and take-up reels in the cassette when the cassette is removed from the print carriage, and automatically disengages the brake mechanism when the cassette is mounted to the print carriage.

Abstract: A digitizer tablet with a cordless transducer which is capable of providing to the tablet information relating not only to the position of the pointing device but also with respect to the status of any button switches on the transducer. This is obtained by providing a plurality of oscillators, connected in circuits in which the relative ratio of the signal frequency outputs of the oscillators can be varied in response to activation of a switch while at the same time the sum of the amplitudes of the oscillating signals remain constant. Thus, the determination of the sum can be used as a indication of the position of the pointing device with respect to the tablet, whereas by determining the differences in the signal intensities of the different frequency oscillating signals, it is possible to determine the status of the button switches on the pointing device. The invention is typically used with a stylus or cursor driven tablet.

Abstract: Apparatus especially X-Y plotters having a marking device for marking a surface. A support is provided for supporting the marking device. The support is movable along an axis of the housing while the marking device can be selectively raised and lowered relative to the surface. The raising and lowering is carried out by means of a flexible driving element, for example, a cable, connected to a pivotable link on the support and activated by a motor. The marking device support is freely translatable relative to the flexible driving element.

Abstract: Motor-driven cutting apparatus for cutting sheet media are disclosed, particularly for use with plotter and printer apparatus. The cutting apparatus of one embodiment comprises two cutting members in which at least one of the cutting members is moved both angularly and linearly, e.g., pivoted and reciprocated, relative to the other to cut media placed between the two cutting members. In another embodiment, the cutting members are both simultaneously pivoted relative to each other. Rotary motion of a driving member, e.g. a motor shaft or a shaft coupled to a motor shaft, is converted to combined angular and straight line motion or only angular motion at one or both cutting members by a simplified coupling arrangement which may comprise simple sleeves with eccentric structure and pivot-type joints. Cutting apparatus according to the invention may be used for X-axis and/or Y-axis cutting.

Abstract: A belt-drive tensioning system for a motor drive positioning system, especially for X-Y digital plotters. The tensioning system employs spring-loading involving motion along only one translational direction to accurately preset and maintain constant the desired belt tension. Preferred embodiments to provide a self-contained modular unit include a dual plate assembly in roller-bearing relationship, and the use of V-shaped mounting springs.

Abstract: Apparatus is disclosed for use with printers (or plotters) for storing and transferring ink-containing ribbon cassettes between a print head and a storage location. The printers (or plotters) are of the type which include a print head that is not as wide as the width of the medium to be printed on so that the print head has to be moved to print (or plot) across the full width of the medium. The apparatus automatically removes a cassette mounted to the movable carriage to which the print head is also mounted and deposits it in the storage station, and automatically removes a selected cassette from the storage station and deposits it on the print carriage. The apparatus includes cassette holders at the storage location and a cassette holder mounted to the print carriage.

Abstract: Method and apparatus are disclosed for determining the diameter of sheet material wound on a reel, and for setting the tension on sheet material as it is wound on the reel. According to one embodiment, the diameter of a take-up reel including sheet material wound thereon is determined from the angle of rotation or instantaneous angular speed of the take-up reel, and movement of the sheet material as obtained from rotation of a circular element such as a drive roller in a pinch roller drive system which rotates in proportional to sheet material movement. In another embodiment, the diameter of a reel in a reel-to-reel transport system is determined from the angles of rotation or instantaneous angular speeds of the supply and take-up reels, the total amount of sheet material in the system, and the packing factor of the sheet material rewound on the take-up reel.

Abstract: A digitizer tablet providing hysteresis compensation in which the X and Y coordinates of a pointing device are measured at different times. In order to enable the tablet to report X and Y coordinates that when displayed will more accurately reflect the pointing device movements, a correction algorithm, built, for example, into the controlling software, estimates and reports what the first measured coordinate would have been, measured when the second coordinate is measured, based upon the calculated velocity and acceleration of the pointing device. A similar technique can be used to correct the reported value of the second coordinate. In a preferred embodiment, constant coefficients of a linear equation having as variables three consecutive coordinate values or three consecutive preprocessed coordinate values are predetermined and used in the correction algorithm. The preferred embodiment integrates the velocity and acceleration hysteresis compensation into a three point recursive noise filter.

Abstract: A belt drive tensioning system for a motor drive positioning system, especially for X-Y digital plotters. The tensioning system employs spring-loading involving pivoting motion of a motor-mounted plate relative to a fixed plate to accurately preset and maintain constant the desired belt tension. A preferred embodiment provides a self-contained modular unit using two pivot bushings interconnecting the two plates.

Abstract: Disclosed herein are position determining apparatus and conductor structures or grids therefor. The conductor structure for each axis includes a number of conductors which are run in a serpentine-type path each with uniform repeat increment. The repeat increment, which is the spacing or span between one run and the next of the same serpentine-type conductor, are uniform for each conductor (but may change from conductor to conductor) and is constrained by a maximum repeat increment, or a minimum repeat increment. In the preferred embodiments, there is at least a constraint on the maximum repeat increment to provide noise immunity. The conductors are arranged for each axis of the grid in a pattern such that signals obtained for that axis may be processed to provide binary numbers in a Gray-type code each unique to a small region of the active area in which the coil center is located.

Abstract: An electromagnetic digitizer tablet comprising an array of conductors having plural, spaced, similar active portions regularly and uniformly distributed throughout the active tablet region, together with additional structure to distinguish pointing device positions over the similar active portions. This arrangement reduces the number of individual conductors required. In a preferred arrangement, the active portions have a block S shape. As a further feature, novel algorithms are used to calculate the fine location of the pointing device.

Abstract: An accessory for improving the accuracy, and/or facilitating the use, and/or improving aesthetics and/or ergonomics of digitizer cursors is disclosed. The accessory mounts an optical element to the position-sighting aperture on the cursor. In all embodiments, the accessory or accessories may be completely and easily removed from the cursor (and replaced). Optical elements may be interchanged and combined so as to permit the operator to select optics that are most efficient for a particular digitizer task. In particular embodiments, the lens is mounted directly to the position-sighting aperture or to another member which is directly mounted to the position sighting aperture. In some embodiments, the optical element is pivotally mounted so that it can be moved into and out of the operator's line of sight. This allows the operator to move the optical element out of his line of sight to the position-sighting aperture without removing the optical element from the cursor.

Abstract: A digitizer table which employs low pass filtering of raw coordinate data to reduce noise and jitter. A weighted filtering is employed, in which the new position data is averaged with a previous average or previous position data before being reported. The weighting factor applied to the new data is determined by the degree of monotonicity represented by the data, with intentional movements of the pointing device indicating high monotonicity undergoing light filtering but noise indicating low monotonicity undergoing heavy filtering.

Abstract: A digitizer system comprises a source of a light for producing an image, a shutter, and a transparent or translucent digitizer tablet. The source is positioned to direct the image to the tablet via the shutter. The shutter comprises a liquid crystal layer and transparent planar conductors on opposite surfaces of the layer. The system further comprises a source of an adjustable voltage connected between the planar conductors for adjusting the transmissivity of the shutters.

Abstract: A digitizer tablet exhibiting improved regional error correction comprises evaluation of two linear equations to correct the generated raw coordinates. The equations contain certain constants unique to tablet regions exhibiting similar error patterns. These constants are empirically determined and stored for use in the evaluations.

Abstract: A stylus switch is activated automatically when the tip of the stylus is pressed against a digitizer tablet with sufficent force. The pressure switch inlcudes a transducer in the form of an ink layer having electrical resistance which varies as a function of the pressure applied thereon. Electrodes of conductive ink contact the ink layer of the transducer, providing a circuit element including a variable resistance. The current which flows between the two conductive ink electrodes varies as a function of the force with which the stylus tip is pressed against the data tablet, thus providing an analog output which can be detected as a function of pressure or which can be detected to determine when the pressing force exceeds a predetermined value. Processing of the data representing the coordinates of the stylus tip is enabled only when the tip is being pressed with at least a predetermined force, i.e. the amount of force applied by a stylus user during writing.