Abstract:
A barcode scanner with configurable video modes which enhances readability of a wide range of barcode types. The barcode scanner includes a video circuit, and a configuration circuit for altering operating characteristics of the video circuit during a scanning operation for reading a plurality of different types of barcodes.

Description:
BACKGROUND 
   The video front end circuitry of a barcode scanner is tuned to respond to less-than-perfect signals coming from the laser spot crossing over a barcode label. Barcode label characteristics can vary. For example, barcode density or frequency and print quality may vary. Print quality is affected by overprinting or underprinting, speckles between transitions which create noise, and print intensity or contrast. 
   A barcode scanner might have several channels where the video circuit in each channel is tuned to optimize the reading with regards to any of the variables previously mentioned. Less expensive barcode scanners with fewer or only one video channel cannot easily be optimized to read different types of barcodes. A barcode scanner with only one video channel has a static circuit which cannot be optimized to read all barcodes that vary widely. 
   It would be desirable to provide a barcode scanner with configurable video modes in a barcode scanner. 
   SUMMARY 
   In accordance with the present invention, a barcode scanner with configurable video modes is provided. 
   The barcode scanner includes a video circuit, and a configuration circuit for altering operating characteristics of the video circuit during a scanning operation for reading a plurality of different types of barcodes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of an example optical barcode scanner; 
       FIG. 2  is a block diagram of an analog video preprocessing circuit in the optical barcode scanner; and 
       FIG. 3  is a flow diagram illustrating the method of configuring video modes. 
   

   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , an example optical scanner  10  includes laser  12 , mirrored spinner  16 , pattern mirrors  18 , collector  20 , detector  22 , video circuitry  28 , and control circuitry  32 . 
   Laser  12  produces a laser beam. 
   Mirrored spinner  16  directs the laser beam to pattern mirrors  18  and directs light reflected from bar code label  42  to collector  20 . 
   Motor  26  rotates mirrored spinner  16 . 
   Sensor  24  produces a signal for deriving the position of mirrored spinner  16  on its rotational path. Sensor  24  may include a Hall effect device, which produces a fixed number of pulses each time motor  26  rotates one revolution. Sensor  24  sends the pulses to control circuitry  32 . 
   Patter mirrors  18  direct the laser beam towards bar code label  42  and direct the reflected light to mirrored spinner  16 . 
   Collector  20  collects the reflected light and directs it towards detector  22 . 
   Detector  22  converts the reflected light into electrical signals. 
   Video circuitry  28  extracts barcode data from the electrical signals. Video circuitry  28  includes analog video pre-processing circuitry  34  and digital video processing circuitry  36 . Example optical scanner  10  includes only one video channel, but the concepts disclose herein may be applied to scanners with more than one video channel. 
   Analog video pre-processing circuitry  34  produces analog video signals and sends the signals to digital video processing circuitry  36 . 
   Digital video processing circuitry  36  extracts barcode data from pre-processed signals. 
   Control circuitry  32  controls operation of scanner  10 , decodes barcode data from video circuitry  28 , and sends decoded barcode data to computer  50 . Control circuitry  32  additional changes the operating characteristics of analog video pre-processing circuitry  34  based upon the position of mirrored spinner  16  and configuration settings  70  in memory  72  ( FIG. 2 ). 
   Referring now to  FIG. 2 , analog video pre-processing circuitry  34  is illustrated in further detail. 
   Analog video pre-processing circuitry  34  includes preamplifier  60 , bandpass filter  62 , threshold generator  64 , analog to digital (A/D) converter  66 , and configuration circuit  68 . 
   Preamplifier  60  amplifies the output signal from detector  22 . 
   Bandpass filter  62  filters out frequency extremes. 
   Threshold generator  64  establishes a comparison threshold level for the filtered analog signal. 
   Both bandpass filter  62  and threshold generator  64  include passive electronic components. Noise coming from preamplifier  60  must be considered during the design of bandpass filter  62 . Several different discrete component values that characterize bandpass filter  62  and threshold generator  64  may be empirically determined. 
   A/D converter  66  converts the filtered and thresholded analog signal to a digital signal, which is further processed by digital video processing circuitry  36  and ultimately decoded by control circuitry  32 . 
   Configuration circuit  68  alters operating characteristics of analog video pre-processing circuitry  34  in response to a control signal from control circuitry  32 . The control signal is based upon spinner position information from position sensor  24 . In one example mode of operation, configuration circuit  68  changes the operating characteristics with each revolution of mirrored spinner  16 . 
   Configuration circuit  68  may vary operating characteristics of bandpass filter  62  and thresholds from threshold generator  64  based upon predetermined ranges of barcode densities, contrasts, and print qualities. Configuration settings  70  for different barcode scenarios are stored in memory  72 . 
   Configuration circuit  68  may automatically cycle through all configuration settings  70  during each revolution of mirrored spinner  16 , in response to a control signal from control circuitry  32 . Thus, scanner  10  may read a wider range of barcode labels during a single scanning movement. As an additional option, configuration circuit  68  may be programmed via script or otherwise to emphasize configuration settings for more popular barcode densities and print qualities during each cycle. For example, configuration circuit  68  may apply the configuration settings for the more popular barcode densities and print qualities twice as often as less popular barcode densities and print qualities. 
   With reference to  FIG. 3 , this example embodiment is illustrated in more detail, beginning with START  80 . 
   In step  82 , configuration circuit  68  loads a script into memory  72  upon bootup, if the script is not already in memory  72 . Configuration circuit  68  may obtain the script from an attached computer, such as a point-of-sale (POS) terminal, through control circuitry  32 . 
   In step  84 , control circuitry  32  waits for a scanning operation. Operation proceeds to step  86  if a scanning operation has begun. 
   In step  86 , control circuitry  32  activates laser  12  and motor  26 , if they are not already activated. Control circuitry  32  may activate laser  12  and motor  26  in response to a signal from a sensor in the scanning path. 
   In step  88 , control circuitry  32  waits for a signal from spinner position sensor  24 . Following receipt of the signal, operation proceeds to step  90 . 
   In step  90 , control circuitry  32  sends an enable signal to configuration circuit  68 . 
   In step  92 , configuration circuit  68  reads configuration settings  70  from memory  72  and alters operating characteristics of analog video pre-processing circuitry  34  in accordance with the configuration settings  70 . As the script calls for different configuration settings  70 , configuration circuit  68  reads the different configuration settings from memory  72  and executes them. 
   In step  94 , control circuitry  32  determines whether all scanning operations have finished. If so, operation returns to step  84 . Otherwise, operation proceeds to step  88 . 
   This solution offers a cost-effective approach to providing multiple video front ends in barcode scanner  10 . From a performance point of view, barcode scanner  10  can operate on a wider range of barcode densities and print contrast levels. 
   Although particular reference has been made to certain embodiments, variations and modifications are also envisioned within the spirit and scope of the following claims.