Abstract: The present invention provides an external rotor stepper motor consisting of four individual, independently controlled, co-planar stepper motors optimized for vehicle direct wheel drive applications. The innovative design eliminates the need for bifilar coil winding, each of the motors' coils being single conductor, each coil being wound in the same direction throughout the entire motor. Each of the four independent motors is simultaneously energized. Because adjacent, outside coils of adjacent motors are simultaneously energized at the same polarity, there is substantially no energy wasting cancellation of magnetic flux. Carefully chosen radially spacing of the four independent, co-planar motors also eliminates substantially all flux interaction between the motors. Because similar coils of the four motors are all connected in parallel, the net inductance presented driver circuits is minimized. This yields fast rise time pulses and improved efficiency through minimized reactance of the motor.

Abstract: A movement sensor for a multi-bar positioner includes a first section having a curved corner reflector (76), a second section (70), and a third section with an analog position-sensitive-photodiode (84). The second section (70) has three LEDs (72, 82) and four photodetectors (74). Two of the LEDs (72) and the four photodetectors (74) face a first direction towards the corner reflector (76). The third LED (82) faces a second direction, different than the first direction, towards the position-sensitive-photodiode (84). The second section can be mounted on an arm of the positioner and used in conjunction with the first and third sections to determine movement or position of that arm.

Abstract: An apparatus for positioning an end-effector comprising a multi-bar linkage drive mechanism. The drive mechanism has a base structure of a movable arm structure. The moveable arm structure has four arms arranged in a general parallelogram profile with a center of gravity at a main shaft located at a connection of two of the arms. Two of the arms have energizeable electromagnetic coils and the base structure has permanent magnets for moving the arms. Analog and/or digital position sensors can be used. Dynamic balancing can be provided to produce reactionless ultra-high speed X-Y motion. A torque cancellation motor for cancellation of Z-axis moments produced by these coils can be provided. A Z-direction actuator can also be provided.

Abstract: An actuator for use in positioning a probe. The actuator has a magnet, two C-shaped cores on opposite sides of the magnet, an electromagnetic coil, and an armature movably connected with the cores. The armature has a projecting face located over portions of both pole faces for each core for the entire range of motion of the armature. The armature is primarily retained with the cores by magnetic attraction by the magnet. The actuator also has an armature position sensor which can include either an optical sensor or a magnetic sensor. A test probe is mounted to the armature which can be preloaded and have dual springs to prevent scrubbing and increase contact force with an object being tested.

Abstract: Alternately stacked radial-pole stator and spacer laminations provide a simple linear actuator, in which alternating layers form magnetic teeth in the axial direction. The spacer laminations are non-ferromagnetic or dimensionally spaced from the flux path. The stator laminations have radially extending pairs of poles, forming a central hole which may be filled and ground smooth along with the spacers, forming smooth pole faces upon which the armature may slide.Flux paths are coplanar with stator laminations, thus making each lamination completely independent. Electromagnetic force increases linearly as stator laminations are added. The stacked stator laminations have pole faces each having a finite pole face flux capacity; related armature rings can be mounted on a nonmagnetic support tube and made as light as possible so long as each ring is of sufficient cross-sectional area to carry half the pole face flux capacity.

Abstract: A high resolution positioning sensor having a magnetic field generator, a device connected to the magnetic field generator for concentrating lines of magnetic flux produced by the magnetic field generator, and a magneto resistive element connected to the concentrating device. The magneto resistive element is adapted to change resistive properties as a function of magnetic flux density. A reference position scale is also provided, having a transducer grid with a number of protuberances. Two flux couplers are connected to the magneto resistive element and are arranged out of phase with one another with respect to the protuberances of the transducer grid. These flux couplers modulate flux distribution between the concentrating device and the transducer grid.

Abstract: A high performance, low cost variable reluctance stepper motor has an integral structure with a ring and a plurality of aligned salient pole members. A plurality of teeth are located on the face of each pole member. Windings are disposed on alternate ones of the pole members and a high impedance means isolates the pole members from one another. A rotor with a plurality of teeth and a plurality of holes disposed thereon coacts with the pole members and is moved in a step fashion by the sequential energization of the windings. The flux generated by the energization of the windings is confined to a short path and coupling to the remainder of the structure is negligible. Recesses positioned symmetrically around the structure also serve to enhance flux splitting and reduce adjacent flux coupling.

Abstract: A method of and apparatus for controlling gray scale in the charge sensitive media of a matrix printer by using constant amplitude write pulses. Their use is intended to overcome registration problems caused by constant movement of the charge sensitive recording media during the actual print cycle. This control method and apparatus are implemented by varying, as a function of the desired intensity of one or more pixels to be printed, the effective write time and the number of constant amplitude pulses applied to any one or more of a plurality of print electrodes over a complete write cycle. The normal printer write cycle is divided into a number of subdivisions, that number being a function of the maximum permissible allowable error that can be perceived by a human eye. Further, the write pulse waveforms used are derived so that there is not more than one write cycle subdivision difference at either termination point of any intensity pixel printed therewith.

Abstract: A preheating pad and assembly for electrolytic printing apparatus is provided. The pad is adjustably mounted to the write head of the printer for movement normal to the recording medium used therein. The pad is fabricated from a ceramic chip and includes a resistive heating element that is protected by a thin bottom layer provided for that purpose.It is joined to an insulated carrier arm by a spring which serves to electrically and mechanically couple the pad and the print head. The biasing effect made possible by the spring allows the pad contact pressure with the recording medium surface to be tuned or adjusted as required. In operation, the pad's position is adjusted to force moisture deposited by an applicator on the surface of the recording medium to penetrate the recording medium's surface layer while simultaneously heating both the surface layer's constituent materials and the fluid being driven therein.