Abstract: An improved method and apparatus for handling saturation conditions in the digital compensator of a control system. A clipping limiter is incorporated in the digital compensator for outputting both a limited signal to be sent to the actuator, and for outputting a clipping signal indicative of a difference between the input and the output of the clipping limiter. The clipping signal is delayed by one sample period, and fed back to the input to the compensator in order to provide a correct amount of compensation when the system is operating at or near saturation.

Abstract: A bar code reader mirror oscillator is disclosed herein. The oscillator includes a permanent magnet having first and second poles of opposite polarity and an electromagnet having a core with first and second pole locations. The permanent magnet is fastened to a mirror carrier resiliently mounted to a frame to oscillate about a rotational axis, wherein the electromagnetic core is fastened to the frame so that the poles of the permanent magnet are equidistant from the pole locations of the electromagnet. This oscillator configuration directs substantially all of the energy applied to the electromagnet to the production of oscillatory motion in the associated reader mirror.

Abstract: A bar code reader for reading bar codes falling within a rectangular scan area having two vertical sides, a top and a bottom is disclosed herein. The reader includes two oscillating mirrors operable to scan a light beam over the area. Each mirror is oscillated by an assembly controlled by a control circuit which produces controls signals which define the rate and frequency at which the mirrors are oscillated. More specifically, the mirror which sweeps the light beam between the vertical sides of the area is oscillated at a constant frequency, and the mirror which causes the mirror to progressively sweep between the top and bottom of the area is rotated so that a greater number of sweeps occur when the light beam progresses from the bottom to the top of the area than when the light beam progresses from the top to the bottom of the area.

Abstract: A bar code reader including a dynamic damper for an oscillating mirror assembly is disclosed herein. The reader includes a frame which supports a light source for producing scanning light, and a transducer for receiving scanning light reflected from a bar code being read by the reader. The light produced by the light source is scanned over the bar code by an oscillator assembly including a carrier defining a rotational axis, a light reflector fastened to the carrier, and a spring assembly fastened to the carrier and the frame to resiliently support the carrier for oscillation about the rotational axis. A damper fastened to the frame and slidably engaged with the carrier is provided to inhibit oscillation of the carrier perpendicular to the rotational axis. Such undesirable oscillation is typically caused by forces external to the scanner such as jarring of a structure supporting the scanner.

Abstract: An optical code reader having an improved mirror support is disclosed herein. The optical code reader is of the type which scans a code with a light beam and determines the information embodied in the code by decoding signals representative of the portions of the light beam reflected from the code. The scanning motion of the light beam is produced by a mirror supported for oscillation at a predetermined frequency. In particular, the mirror is supported by a shaft which is supported relative to the frame of the reader by two sets of four U-shaped springs. One set of springs is fasted between the first end of the shaft and the frame and the second set is fastened between the second end of the shaft and the frame. This spring configuration supports the mirror and shaft for oscillation about a desired rotational axis without the use of bearings.

Abstract: A bar code reader of the type which directs a light beam to scan an area (i.e. raster scan) is disclosed herein. The reader includes first and second oscillating mirrors for directing a light beam from a photodiode to a bar code, and for directing portions of the light beam reflected from the bar code back to a photodetector which generates an electrical signal representative of the information embodied in the bar code. The first oscillating mirror scans the light parallel to a first line (e.g. vertical line) at a first frequency onto the second oscillating mirror. The second oscillating mirror scans the light from the first mirror parallel to a second line (e.g. horizontal line perpendicular to the vertical line) at a second frequency greater than the first frequency onto the bar code. The first mirror may be a compound mirror having a concave, reflective surface which circumscribes a flat, reflective surface.

Abstract: A motor control system and the electrical bus for interconnecting the components of the control system are disclosed herein. The system includes a main motor control unit connected to four motor axis control modules. The control algorithms and commands for the system are stored and executed by the control unit which communicates control commands to the individual motor axis control modules. Each motor control module processes the control commands to control a motor connected to the module, and also communicates feedback signals produced at the associated axis to the control unit. The interconnection between the control unit and the modules is positioned at the face of the components to facilitate removal and insertion of the modules. The electrical bus includes both communications conductors and power conductors, and is included in the interconnection of the components.

Abstract: A bar code reader and the mirror oscillating system thereof are disclosed herein. The bar code reader is of the type which produces a scanning light beam by oscillating at least one mirror with a electromagnetic oscillator. The electromagnetic oscillator includes a winding which is energized with an alternating current signal produced based upon a position signal generated by a magnetic pickup. The position signal is representative of the location of the mirror. The position signal is amplified, phase-shifted, and assigned a duration based upon the difference between the desired angle of mirror oscillation and the actual angle of oscillation to produce the alternating current signal which is applied to the winding. When applied to the winding, the alternating current produces an alternating magnetic field which interacts with a permanent magnet fixed relative to the mirror to oscillate the mirror.

Abstract: A bar code reader including automatic scan beam focusing based upon decoding performance is disclosed herein. The bar code reader includes a focusing lens which is movably supported along the light path of the scanning beam. An electric motor is coupled to the lens support to move the lens relative to the light beam source in response to control signals. The control signals are produced based upon the data error rate for the data produced by the decoding circuit of the reader from the signals produced by the photodetector therein. Based upon the data error rate, the electric motor is controlled to move the lens to focus the light beam and reduce or eliminate the data error.

Abstract: A bar code reader for reading two-dimensional bar codes is disclosed herein. The reader includes first and second oscillating mirrors which oscillate to scan the light beam of the reader over the code. The first mirror is oscillated about a horizontal axis at a first velocity during the first half of its oscillating cycle, and at a second velocity during the second half of the oscillating cycle. The second mirror is oscillated about a vertical axis at a generally constant frequency. The reader varies the first and second velocities based upon the error rate monitored during decoding. By varying the first and second velocities, the slope of the scanning lines can be varied to enable reading two-dimensional bar codes which are oriented at slopes which differ from bar code to bar code.

Abstract: The present invention provides a circuit breaker trip unit configured to operate with a plurality of different plug-in display units. The display unit includes a memory which stores data representative of the particular display unit, and which allows the trip unit to automatically adapt to communicate with the display modules. The trip unit includes a processor and programming which permits a bi-directional flow of data between the units, such as display data and control data.

Abstract: Assemblies for providing the contacts of a circuit breaker with a pivoting motion. Each assembly is adapted to electrically couple the contact to the base of the assembly which is connectable to a terminal of the circuit breaker. Each assembly includes an arm for supporting an electrical contact, a pivot pin for pivotally mounting the arm, a base for supporting the pivot pin, and means for urging the pivot pin into contact with contact surfaces of the base. The arm is pivotable about the longitudinal axis of the pivot pin, and the arm and pivot pin are arranged such that at least two contact locations occur between the arm and the pivot pin.

Abstract: A circuit breaker including a contact operating mechanism configured to prevent the switch handle of the circuit breaker from being placed in an OFF position when the contacts are not separable. In addition to the switch handle, the mechanism is operable with a tripping circuit which actuates the mechanism to urge the contacts apart when the current flowing through the circuit breaker exceeds the preset limits of the circuit breaker. When the contacts are not separable and the tripping circuit actuates the mechanism, the operating handle is restricted from being placed in the OFF position, thereby avoiding the possibility of indicating an incorrect position of the contacts.

Abstract: A load center enclosure according to the invention has a unitary plastic frame of uniform cross-section, including a central base pan portion having projections, slots, and the like suitable for mounting bus bars, circuit breakers and neutral bars thereon. The frame also has a rear wall and a pair of opposed side walls which form part of the enclosure, the base pan portion serving as part of the rear wall of the enclosure. A pair of covers are secured to opposite ends of said frame to form top and bottom walls of said enclosure. A door assembly may then be mounted on the front of the enclosure. Such a load center enclosure utilizes an extrudable plastic frame as both a major component of the enclosure and as a base pan for mounting the current-carrying electrical components.

Abstract: An electrical enclosure (10) having a box (12) having an open side, a trim panel (20) for covering the box open side, a support tab (22) and an aperture for receiving the support tab (22). A portion of the aperture edge may be formed by a flange edge (18). The support tab (22) supports the weight of the trim panel (20) during installation of trim panel fasteners (28) into holes (16, 24) formed in the box (12) and trim panel (20), respectively. The support tab (22) may be formed simultaneously with the trim panel fastener hole (24) in a stamping operation.

Abstract: Power is supplied to a computer facility by a plurality of electrical plug-in busways fed by a power distribution unit. The power distribution unit includes circuit breakers for the busways served. Powered equipment is connected by its own power cable to the busways via a plug-in cable tap box having an approprate receptacle for the particular equipment and also housing a circuit breaker dedicated to that equipment.

Abstract: A multi-phase switch assembly (10) has a base (12) and an operating mechanism (14). The base (12) and operating mechanism (14) are formed to fit together as an integrated unit by sliding engagement of the base (48) of framework (32) between bosses (30,31) of the base (12) of the switch. Fastener holes (74,76) extend through both the base (12) of the switch and the operating mechanism (14) so that the entire switch assembly (10) can easily be mounted as a unit.

Abstract: A primary disconnect assembly for a circuit breaker. The assembly includes a plurality of contact fingers for engaging the terminals of a bus bar assembly. The terminals and fingers are configured such that the terminals each include depressions adapted to accept the contact portions of the contact fingers. This configuration provides at least two contact locations between each contact finger and terminal. Additionally, this configuration increases the force required to slide the fingers relative to the terminals.

Abstract: A mechanism for accumulating and storing mechanical energy, wherein the energy is used to close the primary contacts of a circuit breaker. The energy can be input to the mechanism manually or by means of a motor. The mechanism includes a series of linkages which function to utilize the energy to close the primary contacts. These linkages also function to maintain the closing force upon the primary contacts, while also functioning to allow rapid contact opening when desired.

Abstract: A low voltage electrical power circuit breaker in which an actuator in the form of a pushrod controls the separation of arcing contacts by an actuating mechanism, a force-actuated mechanical latching assembly is interposed between the pushrod and the actuating mechanism. Under fault current conditions, the current-induced force tending to open the contacts exerts sufficient force on the latch assembly to unlatch it, thereby permitting the contacts to open freely on their own, without waiting for the operation of the actuating mechanism.