Metrologic Instruments, Inc.

Mark Lucera

Xiaoxun Zhu

C Harry Knowles

Frank Check

LeRoy Dickson

Joseph Ralph

Timothy A Good

Mark C Schmidt

Matt Jefferson

A laser scanning system that employs synchronous time-division-multiplexed laser scanning operations and signal processing operations (for bar code detection). A plurality of successive non-overlapping time slots are defined and logically assigned to a unique laser scanning beam and corresponding photosensor. During a given time slot, the laser scanning beam logically assigned thereto is selectively generated (or selectively projected) into the scanning volume while generation (or projection) of the other laser scanning beam is disabled. Moreover, during the given time slot, the photosensor logically assigned thereto is operably coupled to signal processing circuitry that performs bar code detection operations on the data signals derived therefrom while the other photosensor is operably decoupled from such signal processing circuitry. The frequency of time slots logically assigned to a given laser scanning beam and corresponding photosensor is preferably greater than at least two times the highest frequency component expected in the scan data signal received at the photosensor. In other embodiments, the time slots logically assigned to a given laser scanning beam and corresponding photosensor correspond to scanning planes (or scanning plane groups) generated by the given laser scanning beam during revolution of at least one rotating polygonal mirror. In the preferred embodiment, such synchronous time-division-multiplexed laser scanning operations and signal processing operations (for bar code detection) are embodied in a bioptical laser scanning system comprising a plurality of laser scanning stations, each of which produces a plurality of groups of quasi-orthogonal laser scanning planes that are projected within predetermined regions of space contained within a 3-D scanning volume defined between the bottom and side-scanning windows of the system.

Bar code symbol scanning system employing time-division multiplexed laser scanning and signal processing to avoid optical cross-talk and other unwanted light interference

A bioptical laser scanning system employing a plurality of laser scanning stations about a two independently controlled rotating polygonal mirrors. The system has an ultra -compact construction, ideally suited for space-constrained retail scanning environments, and generates a 3-D omnidirectional laser scanning pattern between the bottom and side-scanning windows during system operation. The laser scanning pattern of the present invention comprises a complex of quasi-orthogonal laser scanning planes, including a plurality of substantially-vertical laser scanning planes for reading bar code symbols having bar code elements (i.e. ladder type bar code symbols) that are oriented substantially horizontal with respect to the bottom-scanning window, and a plurality of substantially-horizontal laser scanning planes for reading bar code symbols having bar code elements (i.e. picket-fence type bar code symbols) that are oriented substantially vertical with respect to the bottom-scanning window.

Bioptical laser scanner for six-sided 360&#xb0; POS-based scanning

The effects of paper/substrate noise are significantly reduced in multi-focal zone laser scanning systems by processing analog scan data signals with a scan data signal processor having a plurality of pass-band filters and amplifiers that are automatically selected for passing only the spectral components of an analog scan data signal produced when a bar code symbol is scanned at a particular focal zone in the laser scanning system. Two or more different pass-band filter structures can be provided for use in the scan data signal processor, wherein each pass-band filter structure is tuned to the spectral band associated with a particular focal zone in the laser scanning system. When a bar code symbol is scanned by a laser beam focused within the first focal zone or scanning range of the system, the pass-band filter structure associated with this focal zone or scanning range is automatically switched into operation. Only spectral components associated with the produced analog scan data signal and noise existing over this pass-band are allowed within the analog signal processor. By virtue of the present invention, first and second derivative signals can be generated and processed to produce a corresponding digital scan data signal for use in subsequent digitizing and decoe processing operations, without compromising system performance due to the destructive effects of thermal and substrate noise outside the spectral pass-band of interest for the bar code symbol being scanned.

Laser scanning bar code symbol reader employing variable passband filter structures having frequency response characteristics controlled by time-measurement of laser-scanned bar code symbol elements

A modular omnidirectional laser-based bar code symbol scanning system having at least one scan module insert that is removably disposed (e.g., removably installed) within a system housing (or portion thereof) through a service port (e.g., opening) in the system housing (or portion thereof). The scan module insert is a self-contained unit including at least the following components (in addition to mechanical support structures for such components): at least one laser diode, a rotating scanning element, an electric motor that rotates the rotating scanning element, one or more photodetectors, and analog signal processing circuitry that conditions (e.g., amplifies and/or filters out unwanted noise in) the electrical signal produced by the one or more photodetectors. The scan module insert can optionally include additional components including one or more light collecting optical elements, one or more beam folding mirrors, circuitry for detecting and decoding bar code symbols scanned by the system, etc. The modular architecture of omnidirectional laser scanner of the present invention enables quick access to the scan module insert for efficient repair/reconfiguration/configuration of the optical components, electro-optical, electromechanical components and/or electrical components integral thereto.

Modular omnidirectional bar code symbol scanning system with at least one service port for removable installation of scan module insert

A bioptical laser scanning system employing a plurality of laser scanning stations about a two independently controlled rotating polygonal mirrors. The system has an ultra-compact construction, ideally suited for space-constrained retail scanning environments, and generates a 3-D omnidirectional laser scanning pattern between the bottom and side-scanning windows during system operation. The laser scanning pattern of the present invention comprises a complex of quasi-orthogonal laser scanning planes, including a plurality of substantially-vertical laser scanning planes for reading bar code symbols having bar code elements (i.e. ladder type bar code symbols) that are oriented substantially horizontal with respect to the bottom-scanning window, and a plurality of substantially-horizontal laser scanning planes for reading bar code symbols having bar code elements (i.e. picket-fence type bar code symbols) that are oriented substantially vertical with respect to the bottom-scanning window.

Bioptical laser scanner for six-sided 360&#xb0; Pos-based scanning

A laser scanning system that employs synchronous time-division-multiplexed laser scanning operations and signal processing operations. A plurality of successive non-overlapping time slots are defined and logically assigned to a unique laser scanning beam and corresponding photosensor. During a given time slot, the laser scanning beam logically assigned thereto is selectively generated (or selectively projected) into the scanning volume while generation (or projection) of the other laser scanning beam is disabled. During the given time slot, the photosensor logically assigned thereto is operably coupled to signal processing circuitry that performs bar code detection operations on the data signals derived therefrom while the other photosensor is operably decoupled from such signal processing circuitry. The frequency of time slots logically assigned to a given laser scanning beam and corresponding photosensor is preferably greater than at least two times the highest frequency component expected in the scan data signal received at the photosensor.

A modular omnidirectional laser-based bar code symbol scanning system having at least one scan module insert that is removably disposed (e.g., removably installed) within a system housing (or portion thereof) through a service port (e.g., opening) in the system housing (or portion thereof). The scan module insert is a self-contained unit including at least the following components (in addition to mechanical support structures for such components): at least one laser diode, a rotating scanning element, an electric motor that rotates the rotating scanning element, one or more photodetectors, and analog signal processing circuitry that conditions (e.g., amplifies and/or filters out unwanted noise in) the electrical signal produced by the one or more photodetectors. The scan module insert can optionally include additional components including one or more light collecting optical elements, one or more beam folding mirrors, circuitry for detecting and decoding bar code symbols scanned by the system, etc. The modular architecture of omnidirectional laser scanner of the present invention enables quick access to the scan module insert for efficient repair/reconfiguration/configuration of the optical components, electro-optical, electro-mechanical components and/or electrical components integral thereto.

A laser scanning system including a multi-path scan data signal processor having multiple signal processing paths. Each signal processing path processes the same data signal (which is derived from the output of a photodetector) to detect bar code symbols therein and generate data representing the bar code symbols. And each signal processing path has different operational characteristics (such as low-pass filter cutoff frequencies, amplifier gain characteristics, and/or positive and negative signal thresholds). The varying operational characteristics of the signal processing paths are optimized to provide different signal processing functions (e.g., minimize paper noise, or maximize the scan resolution of the system). The data signal derived from laser scanning is supplied to each path of the multi-path scan data processor, where it is processed (preferably in parallel) to identify signal level transitions therein. A digital scan data signal that encodes such signal level transitions is provided to digitizing circuitry, which converts the digital scan data signal into a corresponding sequence of digital words (i.e., a sequence of digital count values) suitable for bar code symbol decoding.

Multipath scan data signal processor having multiple signal processing paths with different operational characteristics to enable processing of signals having increased dynamic range

An analog scan data signal processor is disclosed, in which a time-domain non-linear substrate noise filter is provided before a first derivative signal generation stage so as to produce, as output, a substantially fixed zero-reference signal level whenever a signal level indicative of a bar code substrate is detected, and the signal level analog scan data signal, whenever a signal level indicative of a bar code element is detected. By virtue of the present invention, it is now possible to reduce the level of substrate noise signals within input analog scan data signals, prior to deriving first derivative signals for subsequent signal processing. Consequently, the accuracy of binary signal level detection within such analog scan data signal processors can be significantly improved, thereby improving the performance of bar code symbol reading systems within which such analog scan data signal processors are employed.

ANALOG SCAN DATA SIGNAL PROCESSOR EMPLOYING A TIME-DOMAIN SUBSTRATE NOISE FILTER FOR NON-LINEARLY PROCESSING ANALOG SCAN DATA SIGNALS AND REDUCING SUBSTRATE NOISE SIGNAL LEVELS THEREIN PRIOR TO FIRST DERIVATIVE SIGNAL GENERATION AND PROCESSING OPERATIONS CARRIED OUT WITHIN SAID ANALOG SCAN DATA SIGNAL PROCESSOR

The zone laser scanning systems by processing analog scan data signals with a scan data signal processor having a plurality of pass-band filters and amplifiers that are automatically selected for passing only the spectral components of an analog scan data signal produced when a bar code symbol is scanned at a particular focal zone in the laser scanning system. Two or more different pass band filter structures can be provided for use in the scan data signal processor, wherein each pass-band filter structure is: tuned to the spectral band associated with a particular focal zone in the laser scanning system. When a bar code, symbol is scanned by a laser beam focused within the first focal zone or scanning range of the system, the pass-band filter structure associated with this focal zone or scanning range is automatically switched into operation using a control signal produced by determining the spot speed of the laser scanning beam producing the analog scan data signal being processed. Only spectral components associated with the produced analog scan data signal and noise existing over this pass-band are allowed within the analog signal processor. By virtue of the present invention, first and second derivative signals can be generated and processed to produce a corresponding digital scan data signal for use in subsequent digitizing and decode processing operations, without compromising system performance due to the destructive effects of thermal and substrate noise outside the spectral pass-band of interest for the bar code symbol being scanned.

MULTI-FOCAL LASER SCANNING BAR CODE SYMBOL READING SYSTEM EMPLOYING A SCAN DATA SIGNAL PROCESSOR HAVING A VARIABLE PASS-BAND FILTER STRUCTURE WITH FREQUENCY CHARACTERISTICS CONTROLLED BY MEASURING THE BEAM SPOT SPEED OF THE LASER SCANNING BEAM PRODUCING THE ANALOG SCAN DATA SIGNAL BEING PROCESSED BY SAID SCAN DATA SIGNAL PROCESSOR

A multi-focal zone laser scanning system for scanning bar code symbols having a minimum bar element width (MBW). The multi-focal zone laser scanning system comprises a laser beam producing device for producing a laser beam, and a laser beam scanning mechanism for scanning the laser beam so as to generate a laser scanning pattern having a plurality of different focal zones. In the system, the scanned laser beam has a minimum beam dimension (MBD) with each focal zone, and the ratio of the minimum beam dimension (MDB) within each focal zone to the minimum bar element width (MBW) of a scanned bar code symbol therewithin (i.e. MDB/MBW) is greater than or equal to 2.0. Consequently, less modulation of the laser scanning beam is required during scanning operations, and therefore, bar code symbols having narrower minimum bar element widths can be resolved.

METHOD OF AND SYSTEM FOR SCANNING BAR CODE SYMBOLS USING A LASER SCANNING PATTERN HAVING MULTIPLE FOCAL ZONES, WHEREIN THE MINIMUM BEAM DIMENSION/MINIMUM BAR WIDTH (MBD/MBW) RATIO IS GREATER THAN OR EQUAL TO 2.0

A scan data signal processor is disclosed for use with a laser scanning system having a plurality of different focal zones within which a laser scanning beam is scanned across one or more bar code symbols and an analog scan data signal is automatically produced. The scan data signal processor comprises a first and second derivative signal generation stages, a second-derivative zero-crossing detector, a real-time bar code element detector, and a control logic circuitry. The first derivative signal generation stage derives a first derivative signal from the analog scan data signal. The second derivative signal generation stage derives a second derivative signal from the first derivative signal. The second-derivative zero-crossing detector detects zero crossings in said second derivative signal. The real-time bar code element detector automatically detects the presence and absence of bar code element data encoded within said analog scan data signal. The control logic circuitry automatically activates the second-derivative zero-crossing detector in response to the detection of the presence of bar code element data encoded within said analog scan data signal, and automatically deactivates the second-derivative zero-crossing detector, in response to the detection of the absence of bar code element data encoded within the analog scan data signal. By virtue of the present invention, it is now possible to enable the detection of zero-crossings occurring in the second derivative of the analog scan data signals only when bar code element data has been detected, indicative that a bar code symbol has been scanned. This results in more accurate generation of digital output signals from the scan data signal processor.

METHOD OF AND APPARATUS FOR PROCESSING ANALOG SCAN DATA SIGNALS DERIVED BY SCANNING BAR CODE SYMBOLS USING A LASER BEAM, WHEREIN A REAL-TIME BAR CODE ELEMENT DETECTOR IS USED TO CONTROL THE DETECTION OF ZERO-CROSSINGS OCCURRING IN THE SECOND DERIVATIVE OF SAID ANALOG SCAN DATA SIGNALS

MULTI-FOCAL LASER SCANNING BAR CODE SYMBOL READING SYSTEM EMPLOYING A VARIABLE SECOND DERIVATIVE SIGNAL PASS-BAND FILTER STRUCTURE HAVING FREQUENCY CHARACTERISTICS THAT ARE CONTROLLED IN A REAL-TIME MANNER BY DETECTING BAR CODE ELEMENTS IN ANALOG SCAN DATA SIGNALS PRODUCED BY SAID SYSTEM

The effects of paper/substrate noise are significantly reduced in multi-focal zone laser scanning systems by processing analog scan data signals with a scan data signal processor having a plurality of pass-band filters and amplifiers that are automatically selected for passing only the spectral components of an analog scan data signal produced when a bar code symbol is scanned at a particular focal zone in the laser scanning system. Two or more different pass-band filter structures can be provided for use in the scan data signal processor, wherein each pass-band filter structure is tuned to the spectral band associated with a particular focal zone in the laser scanning system. When a bar code symbol is scanned by a laser beam focused within the first focal zone or scanning range of the system, the pass-band filter structure associated with this focal zone or scanning range is automatically switched into operation. Only spectral components associated with the produced analog scan data signal and noise existing over this pass-band are allowed within the analog signal processor. By virtue of the present invention, first and second derivative signals can be generated and processed to produce a corresponding digital scan data signal for use in subsequent digitizing and decode processing operations, without compromising system performance due to the destructive effects of thermal and substrate noise outside the spectral pass-band of interest for the bar code symbol being scanned.

Scan data signal processor employing band-pass filter having frequency response characteristics controlled by the depth of focus of the laser scanning beam

MULTI-FOCAL LASER SCANNING BAR CODE SYMBOL READING SYSTEM EMPLOYING A SCAN DATA SIGNAL PROCESSOR HAVING A VARIABLE PASS-BAND FILTER STRUCTURE WITH FREQUENCY CHARACTERISTICS CONTROLLED BY DETECTING THE FOCAL DISTANCE OF THE LASER SCANNING BEAM PRODUCING THE ANALOG SCAN DATA SIGNAL BEING PROCESSED BY SAID DATA SIGNAL PROCESSOR

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Pine Hill, NJ, United States of America

Mark Lucera