Abstract: A transmitter for an alignment system in which a field of electromagnetic radiation is propagated in a non-planar reference cone is disclosed. The transmitter includes a chassis with a source fixed to the chassis for providing a beam of electromagnetic radiation and an optical deflector which converges toward the source reflects the beam into an omni-directional cone of radiation. A flexible support having an omni-directional stiffness supports the optical deflector in the beam to reflect the reference field in a level orientation when the chassis is level. An angular error in the orientation of the chassis from level results in the optical deflector deviating from the aligned position to maintain the reference field in the level orientation. Damping of the deflector is also provided for and sensors detect when the angular error of the chassis has exceeded an allowable amount.

Abstract: A transmitter for an alignment system in which a field of electromagnetic radiation is propagated in a non-planar reference cone is disclosed. The transmitter includes a source for providing a collimated beam of electromagnetic radiation directed parallel to a beam axis. A cantilever strand supports a bob within the beam. The bob has a conical reflecting surface to reflect the collimated beam conically. Optimally, the cantilever strand and bob are chosen to provide a deflection between the bob and plumb which is substantially one-half of any angular error between the beam axis and plumb. In an especially preferred form, a housing surrounds the bob and has inner and outer surfaces which minimize temperature effects on the orientation of the reference plane. Also, detectors are provided to sense when the angular error between the beam axis and plumb is outside of an acceptable range.

Abstract: Apparatus for projecting a laser beam to provide simultaneously a stationary reference beam and a moving reference beam, which rotates in a plane normal to the stationary reference beam, includes a beam diverting arrangement for intercepting a primary beam and for splitting the beam into the two reference beams. The beam diverting arrangement includes first and second deflecting elements which deflect the beam by 90.degree. with respect to the primary beam. A portion of the primary beam, striking the first deflecting element, passes through the element and is shifted slightly by refraction. This shift is compensated by a third beam deflecting element which is fully transmissive, and which refracts the stationary reference beam into alignment with the primary beam. By cutting the first and third deflection elements from the same sheet of material and reorienting the elements appropriately, slight deviation from parallelism in the opposing surfaces of the sheet of material are compensated.

Abstract: A laser beam projection device includes a laser plasma tube assembly having a laser plasma tube and a generally cylindrical casing surrounding the tube. The plasma tube is positioned within the casing such that the beam produced by the tube is aligned with the casing and emerges from the casing through a circular opening at one end thereof. A support frame is provided for mounting the laser plasma tube assembly and also for mounting one or more optical elements in precise alignment with respect to the beam produced by the tube assembly. The frame includes an annular member for engaging the circular opening in the casing in order to align the casing with respect to the frame. The frame further defines a pair of non-parallel alignment surfaces, spaced from the annular member, to contact the outer surface of the casing near the end thereof opposite the circular opening. The casing defines an inner beveled surface surrounding the opening through which the beam emerges.

Abstract: A CRT terminal includes a main unit which houses circuitry and the CRT display. An application module which includes a keyboard plugs into the front of the main unit and electrically connects to its circuitry. A flexible membrane keyboard is employed which includes a keyboard overlay that is easily changed to provide keyboard symbols appropriate to a wide variety of different applications. Resilient bumpers extend completely around the main unit to facilitate its use in industrial applications where physical abuse is common.

Abstract: A CRT terminal includes a main unit which houses circuitry and the CRT display. An application module which includes a keyboard plugs into the front of the main unit and electrically connects to its circuitry. A flexible membrane keyboard is employed which includes a keyboard overlay that is easily changed to provide keyboard symbols appropriate to a wide variety of different applications. Resilient bumpers extend completely around the main unit to facilitate its use in industrial applications where physical abuse is common.

Abstract: A program protection module for a programmable controller checks the critical, or protected, portion of the control program each time the controller is switched to the run mode. This is accomplished by reading each control program instruction out of the controller memory and comparing it with a corresponding control instruction stored in a nonaccessible read-only memory. If all the compared control instructions are identical, the module sets a status bit in the programmable controller which enables the protected portion of the control program to be executed. If identity is not found, an alarm is generated and the protected program is not executed.

Abstract: A programmable controller includes four remotely located input/output interface racks which are connected by cables to an I/O scanner circuit which is centrally located with the controller processor and memory. Input and output data is serially transmitted between the I/O scanner circuit and the interface racks, and fault processors are located in both the I/O scanner circuit and the interface racks to monitor the operation. The fault processors include fault tolerant detector circuits which ignore erroneous transmissions caused by industrial noise, but which initiate a shutdown process when malfunctions occur. The shutdown process is controlled by a programmable disabling circuit which is responsive to program instructions stored in the controller memory to allow independent, quasi-independent, or dependent operation of the machines connected to each of the four interface racks.

Abstract: A set of circuit boards are mounted side by side and electrical connection is made to terminal pads disposed along one edge of each circuit board by connectors which are carried by swing arms. The swing arms rotatably mount to a wire duct and each pivots between a horizontal position and an upright operating position in which connection is made to the terminal pads on its associated circuit board. Wire terminals on the connector in each swing arm provide termination for wires in the wire duct.