Abstract: A device for indicating the phase of the a full-frequency alternating current (AC) magnetic field signal transmitting from the pointing device of a cordless digitizer and for determining if the phase of a half-frequency alternating current (AC) magnetic field signal transmitting from the pointing device is approximately the same or approximately inverted from an immediately preceding half-frequency signal from the pointing device. The indication of the phase of the full-frequency pointing device signal is used by the digitizer logic circuits to determine the location of the pointing device on the tablet's sensing surface. The information concerning the change in phase of the half-frequency signal is used by the digitizer logic circuits to decode the status of various pointing device buttons. If the phase in the induced half-frequency signal is unchanged from the last, this no-change condition represents one binary state. If the phase has changed, the condition represents the other binary state.

Abstract: An integrated voltage controlled oscillator (VCO) circuit which utilizes the relative capacitance ratio between capacitors and the relative resistance ratio between resistors in an integrated circuit (IC) to output a signal having a predictable frequency for a given control signal voltage. The VCO output frequency will not vary more than 3.0% from one IC chip implementing the VCO circuit, to the next. This low variance between IC chips is derived from the phenomenon whereby the respective ratios of capacitance and resistance between capacitors and resistors in the IC will not vary more than .+-.1.5% from the ratios of like capacitors and resistors on other IC chips. The integrated VCO circuit includes a control signal subcircuit, integrator subcircuit, filter subcircuit, and comparator unit subcircuit.

Abstract: This is a pen cursor structure for a positional digitizing device such as a digitizing tablet or a pen-driven computer. It comprises a structure of an electrically insulating material having a plurality of areas for receiving and carrying electrical components, an inner structure having a plurality of electrical contacts disposed within the areas and a plurality of electrical traces interconnecting the plurality of electrical contacts. The structure is curved about a longitudinal axis to fit within an outer, hollow, pen-shaped housing.

Abstract: In a pen cursor for use in performing writing motions on the surface of a tablet, this is a sensor for mounting in a tip portion of the pen cursor to develop a signal output indicating longitudinal force on a writing tip of the pen cursor. A tip member extends from the tip portion of the pen cursor and is mounted for longitudinal movement. It has a plunger portion extending therefrom within the pen cursor. A resistive member and a conductive member are disposed within the pen cursor behind the plunger portion. The plunger portion forces the resistive member and the conductive member together in electrical contact over a contacting area which is directly proportional to the amount of longitudinal pressure on the plunger portion. A voltage is connected across the contacting area whereby resistance as a function of longitudinal pressure on the plunger portion can be measured.

Abstract: An improvement to a communications system such as a satellite communications system, or the like, wherein a plurality of nodes transmit over a common path on a time sharing basis via a central hub. The method and apparatus permits closer spacing of the communications from the nodes on the path and eliminates wasted delay time. The method comprises designating one of the nodes as the reference node and the remaining nodes as slave nodes. A transmission sequence is begun by having the reference node transmit a repeating, pre-established, pseudo-random, digital sequence at a pre-established bit rate. The reference node continues its sequence, but then omits a portion between the start and end of the sequence. A slave node wishing to join the transmission sequence begins the same repeating, pre-established, pseudo-random, digital sequence at approximately the same pre-established bit rate and then starts transmitting an approximation of the portion of the sequence being omitted by the reference node.