Abstract: A method for determining degrees of freedom of an object, and in particular, to a device for determining up to six degrees of freedom of a head mount display and a handle. A first camera is attached to a head mount display and senses an optically modulated target. The first camera's video output signal is processed with a digital computer to determine the position and orientation of the head mount display. A second camera is attached to a head mount display and senses an optically modulated target attached to a handle. The second camera's video output signal is processed with a digital computer to determine the position and orientation of the handle.

Abstract: A method for determining up to six degrees of freedom of a camera relative to a reference frame comprises sensing an optically modulated target with the camera and processing the camera's video output signal with a digital computer. The target may have a single pattern, multiple patterns, or patterns of varying size. Multiple targets may also be used. A very wide field of view camera may be used in conjunction with a method for removing geometric distortion from the camera's view. Target patterns may be transmissive, reflective, or retroreflective, or may actively emit light. Asymmetric patterns are used to eliminate ambiguity in the recovery of the degrees of freedom.

Abstract: A print engine including a two-dimensional matrix print head is operated by data signals from a raster image processor through a distributed digital controller having a master controller and a plurality of separate controllers each for a separate set of elements along one of the dimensions of the array, specifically the finger control electrodes of an ion projection printing head. The elements along the other dimension of the array (the RF electrodes of the ion projection head) are controlled by the master controller which also controls the timing of writing of the pixel data signals into memories associated with each of the distributed controllers and the timing of the readout of the pixel data to the finger control electrodes in synchronism with the activation of the RF electrodes and the movement of a medium on which the image is printed so as to print portions of each line in sequence (interleaving dots representing pixels on each line) to form the image on the medium.

Abstract: A hand-held, low cost, low voltage surface resistivity meter is provided by a contact surface which is essentially independent of the geometry of the surface to be measured. The use of special materials for the contact surface permits increased accuracy to be achieved at low voltages. Recognition that readings shown simply to the power of 10 are fully useful in characterizing a measured material permits a low cost, low voltage arrangement for the meter.

Abstract: An inexpensive circuit monitors the resistance between a body (e.g., a static dissipative work surface, a tool, etc.) and ground potential, and compares that resistance with high and low resistance values defining a preset resistance range. An operational amplifier is connected to the body and causes current to flow from the body and through the op amp feedback network. A switching arrangement coupled to the operational amplifier alternately switches the amplifier feedback network between low and high resistance values defining lower and upper ends, respectively, of the preset resistance range.