Abstract: An electromagnetic-field-responsive (preferably optical), code-based, graphic data-acquisition system for tracking the operational status of a mobile write-effective component (stylus, eraser, etc.) in relation to a defined writing-surface area. The preferred embodiment features an active optical structure which is disposed adjacent the writing-surface area for creating, by scanning, a defined zone of optical radiation, optically reactive, retroreflective code structure which is joined to the mobile component and which is capable of reacting (reflecting the same) to radiation within the zone when the code structure intersects the zone, a reaction monitoring structure for monitoring the reaction behavior of the code structure and for producing a related response, and interpretation structure which acquires that response and determines therefrom the desired operational-status-tracking information. Modification to this preferred structure are also illustrated and discussed.

Abstract: A system and method for calibrating and monitoring the height of an electromagnetic radiation expanse above a writing surface is described. An electromagnetic-radiation-generating structure is disposed adjacent produce an expanse of radiation in a substantially planar zone near the writing surface. At least one object is located at a first point in the zone remote from the structure. The object is capable of interacting with the expanse to effect the production of quantitative data correlating to the relative distance between the expanse and the writing surface at the first point. A processor receives and processes the data and allows the position of the expanse relative to the writing surface to be monitored. In a preferred embodiment, four calibration strips are placed near the corners of a writing surface in a system employing two beam-generating scanners to provide X, Y and Z information concerning the location of a writing implement relative to a writing surface.

Abstract: A system and method for detecting movement of an object along an axis normal to a planar surface is described. The invention is applied to a graphic data-acquisition system in which a digitized record is produced according to the X, Y and Z location of a writing implement relative to a writing surface. An expanse of electromagnetic radiation is generated in a zone closely adjacent to the writing surface. An electromagnetic-interactive structure is associated with the writing implement at a location where it will interact with the expanse when the pen is in a write mode. The configuration of the radiation-interactive structure and its positioning relative to the expanse allows the production of an analog data stream which may be correlated to relative distance between the tip of the pen and the writing surface. After fine analog data is digitized, a processing routine is used to determine reliably and accurately when the pen has moved to the non-write mode.

Abstract: An electromagnetic-field-responsive (preferably optical), code-based, graphic data-acquisition system for tracking the operational status of a mobile write-effective component (stylus, eraser, etc.) in relation to a defined writing-surface area. The preferred embodiment features an active optical structure which is disposed adjacent the writing-surface area for creating, by scanning, a defined zone of optical radiation, optically reactive, retroreflective code structure which is joined to the mobile component and which is capable of reacting (reflecting the same) to radiation within the zone when the code structure intersects the zone, a reaction monitoring structure for monitoring the reaction behavior of the code structure and for producing a related response, and interpretation structure which acquires that response and determines therefrom the desired operational-status-tracking information. Modification to this preferred structure are also illustrated and discussed.

Abstract: In a line scan fiber optic cathode ray graphic recorder a continuous sheet of light sensitive paper is drawn perpendicularly before a regularly timed intensity modulated beam from the cathode ray tube. Due to gearing inaccuracies and anomalies, the velocity at which the paper is drawn past the beam varies cyclically resulting in a variation in the spacing between each recorded data line on the paper. For higher paper velocities, the recorded lines are closer together, and for lower paper velocities, the recorded lines are farther apart. The closer lines create a darker image band on the paper and the more distant lines create a lighter image band on the paper. The present invention includes paper velocity monitoring means which provides an input signal to a compensation circuit for inversely varying the intensity information of each pixel dot as a function of the paper velocity.

Abstract: A graphic input system determining position coordinate data of a mobile element on a writing surface by measuring the transit times of ultrasonic signals and an electromagnetic signal. The mobile element may comprise either a writing instrument or an eraser. The electromagnetic signal contains information that represents the color of ink used in the writing instrument and identifies the portion of the eraser in contact with the writing surface.