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 one mirror with a electromagnetic oscillator and a raster scanning device. The raster scanning device includes a non-contact sensor which produces a position signal. The position signal is representative of the location of the raster mirror. The position signal is utilized to adjust the motor drive signal which positions the raster scanning device. The position signal allows the motor a low cost sheet metal stepper motor to be positioned more accurately despite performance degradation over the life of the motor.

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 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: 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: 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 wiring base for a bar code scanner or the like provides a conductive housing open at one face for connecting cables at various screw terminals to a circuit board providing signal processing for the signals and permitting various different-connections of the cables. The shields of the cables pass into the conductive housing to be terminated on conductive housing thereby enlisting the conductive housing as a shield around all the cables. Attachment of the scanning head to the upper face of the wiring base closes the housing to be free from the egress of dust or liquid and completes a Faraday cage around the connections while connecting two multi-pin connectors one within the base and one within the scanner, communicating the signals to the scanner. A visual indicator attached within the conductive housing indicates the presence of power and its polarity prior to connection of the scanning head to the conductive housing.

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 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 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.