Abstract: A collaborative input system 10 includes a host computer 12. A display 14 is associated with the host computer. The host computer includes a processor 15 configured for executing an application to provide an image 17 on the display 14. At least one electromagnetic digitizer 18 is provided separate from the host computer. The digitizer 18 has an input surface 22 defining a display space that is mapped to coincide with the display 14, and a pen structure 24 operatively associated with the input surface such that proximity of the pen structure with respect to the input surface, as a result of a user's input, is detected by the digitizer.

Abstract: A collaborative input system 10 includes a host computer 12. A display 14 is associated with the host computer. The host computer includes a processor 15 configured for executing an application to provide an image 17 on the display 14. At least one electromagnetic digitizer 18 is provided separate from the host computer. The digitizer 18 has an input surface 22 defining a display space that is mapped to coincide with the display 14, and a pen structure 24 operatively associated with the input surface such that proximity of the pen structure with respect to the input surface, as a result of a user's input, is detected by the digitizer.

Abstract: Methods and apparatus are shown for correcting velocity-induced offset errors in a digitizing system when the cursor is moved diagonally across a sensing grid. Primarily, this is a system for reducing the offset error in the actual and depicted cursor position when a pen cursor is moved rapidly over a digitizing screen of a pen-driven computer. It also provides double the number of positional outputs for added accuracy. A triplet of data is formed by taking two samples from one axis and one from the second axis. The two samples are averaged to form one component of the cursor position and then the average along with the single sample from the other axis are output as the positional coordinates. A second sample is then taken from the second axis to form a new data triplet. The averaging process is repeated with the two data points from the second axis and the average along with the second sample from the first axis are output as a next position of the cursor.

Abstract: Methods and apparatus for setting the signal-sampling period of each grid wire in a digitizing tablet having grid wires that are sequentially and repetitively scanned to develop a positional signal related to a cursor so as to reduce jitter associated with non-movement of the cursor and signal error associated with rapid movement of the cursor. The method comprises setting the signal-sampling period of each grid wire to a longest signal-sampling period the digitizer tablet is designed to employ if the cursor is not moving and setting the signal-sampling period of each grid wire to a value inversely related to the present speed of movement of the cursor such that the faster the present speed of movement of the cursor the shorter the signal-sampling period of each grid wire as compared to the longest signal-sampling period the digitizer tablet is designed to employ. The present position of the cursor is then saved as the prior position of the cursor for the next time the steps of the method are performed.

Abstract: A loopback conductor arrangement for a digitizer grid employs rotation sequencing of the conductors. The conductors in each of the X- and Y-directions are looped back and forth in a parallel, spaced relationship across the active grid area so as to provide a plurality of crossing conductor segments, with the positions of selected conductors (e.g., alternate conductors) in each successive loop shifting in sequential positions by a constant offset with respect to the other conductors in those loops.

Abstract: In a digitizer tablet system employing a tablet having equally spaced parallel grid wires disposed in a plane along an axis parallel to the tablet's upper surface and a pen cursor having a sensing coil disposed concentric with and perpendicular to a longitudinal axis of the pen cursor to develop a characteristic output waveform from electromagnetic inductance between the grid wires and the sensing coil, this invention is the method of compensating a calculation of the position of the pen's tip on the tablet's upper surface and along the axis determined from an interpolation of the characteristic output waveform to find its zero voltage crossing point for tilt of the pen cursor longitudinal axis from perpendicular to the tablet's upper surface comprising using voltage values from grid wires next on opposite sides of the zero crossing point to calculate a pen tilt compensation factor.