Abstract: An improved holographic scanner includes circuitry for adjusting the frequency with which an analog photodetector signal is sampled in accordance with the focal length of the scanning beam produced by the active holographic facet. Two embodiments are shown. In one embodiment, facet-edge signals are used to track the facets. A processor retrieves a predetermined frequency scaling factor appropriate for each facet. In the other embodiment, a holographic disk carries an auxiliary data track. The track has timing indicia with spatial frequencies dependent upon the focal length of the adjacent facet. The timing indicia are used to control the output of a voltage controlled oscillator in a circuit including a phase locked loop.

Abstract: A fixed position optical scanner with a multi-faceted holographic disk includes circuitry for adjusting the lockout voltage as a function of the focal length of the active facet. The disk position is tracked to identify the active facet. A facet identifying signal is used to address a lockout table in processor memory. A digital value retrieved from the lockout table is converted to analog form and applied through a resistor to a voltage divider in the threshold circuit. The voltage divider scales down a white peak following voltage and compares it to a black peak following voltage. The facet-dependent lockout voltage biases the junction of the voltage divider to vary the effective lockout voltage as a function of the focal length of the currently active facet.

Abstract: A method for forming UPC or EAN bar code labels from scans of half labels or less than half labels requires that captured data be examined and classified as being either a first type of data configuration or a second type. A first type includes a given number of numeric characters delimited by both margin and center characters. A second type includes either a margin character or a center character and a given number of numeric characters. Labels are formed, where possible, by using appropriate first type data configurations. If labels cannot be formed using only first type configurations, second type configurations are examined to determine if they could represent different portions of the same region (left or right) of a label. If complementary second type configurations are found, they are merged to form a half label. The formed half label may be further merged with a complementary first type data configuration to form a complete label.

Abstract: A system is disclosed for preventing processing of duplicative coded label signals generated by a scanner lacking item detectors. The system establishes a variable lockout time as a function of operator performance. Any detected label candidate which duplicates a candidate received within the lockout time is assumed to be duplicative. Any transfer to the terminal is inhibited. Operator performance is tracked by measuring the inter-item arrival times for candidates actually transferred to the terminal. The inter-item arrival times are averaged over a given number of items. The average value is used to select a lockout time which is generally proportional to the average inter-item arrival time.

Abstract: An optical scanner is improved by securing beam directing holograpic films to the transparent scanner window. The films alter the paths of beams at the window to provide scanning beams suitable for rear or side scanning of label-carrying products. A vertical scanning beam, which sweeps a path parallel to the window's leading edge, might be used to detect the approach of a product to be scanned.

Abstract: An optical scanner uses frequency modulation and detection techniques to produce and utilize multiple, simultaneous scan patterns in which corresponding scan lines have different focal lengths. Two or more solid state lasers are modulated at unique frequencies. The frequency modulated output beams pass through different combinations of focusing lenses and are deflected by a single beam deflecting apparatus. Light reflected from any scanned object is detected. The resulting multi-frequency signal is applied to a plurality of bandpass filters to separate the returned signal into a plurality of separately decodable signals.

Abstract: A data processing terminal device includes a substantially enclosed optical chamber which serves as a wireless communication "bus" between pluggable functional units such as a controller unit, printer units, display units, etc. Each functional unit includes a transducer having an emitter component for injecting optical energy into the cavity and a detector component for sensing optical energy injected by transducers of other functional units. The energy distribution within the cavity is shaped by elliptic parabolic reflectors, preferably molded integrally with the floor of the chamber structure.