Advertorial
SHOWCASE
Accurate Barcode Read Rates on Liquor Bottles
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n the state of Texas, USA a tax stamp must be applied to each liquor bottle sold at the wholesale level, such as to hotels and restaurants. Goody-Goody Liquors Inc., Dallas, Texas, wanted to automate the process of reading the stamps to ensure each bottle has a tax stamp and to store its number in a database with the bottle number for audit purposes.
Cisco-Eagle, the company that built the automated system for applying the stamps, was only able to achieve about 95% accuracy with the first barcode reader that it tried. This meant that the reader failed to read a barcode about every 20 seconds. Next Cisco-Eagle tried the Cognex DataMan® 500 barcode reader and discovered it rarely was unable to read a barcode. “Cognex customer support is remarkable,” said Sam Chen, Senior Robotics and Software Engineer for Cisco- Eagle. “They worked with us continuously to make this application a success.”
Challenging machine vision application
Cisco-Eagle worked with Goody Goody Liquor to develop a system that automatically applies the tax stamps with 1-D barcodes and reads the barcode for verification and tracking. The liquor bottles are processed at high speeds on conveyor belts. An applicator automatically applies the stamp but the system must be able to handle the case where the applicator fails. Machine vision is required to identify bottles that do not have a stamp on them so they can be removed from the line. The image-based reader also captures the tax stamp number so it can be entered into a database along with the bottle number in case of an audit. “We have tried various machine vision systems in the past for this application but have experienced reliability problems,” Chen said. “One of the challenges is that the labels pass by the barcode reader very quickly. The bottles themselves are different with some being round and others being rectangular, which affects the way the barcodes are presented. The line processes many different liquor bottles, many of which provide a background that can be difficult to read against, e.g., very dark, very bright, or striped packaging and opaque or transparent liquid content.
Selection of barcode reader
“We decided to go with the Cognex DataMan 500 barcode reader because it has a larger depth of field, higher resolution, and decoding technology that made it possible to reliably read the barcodes in spite of the challenges of this application,” Chen said. DataMan 500 is the first reader for the logistics industry to use liquid lens autofocus technology that maximizes the depth of field for greater reliability in applications where package position varies. DataMan 500 also offers advanced decoding that makes it possible to easily read badly printed codes, damaged codes, distorted codes, codes on a noisy background, extreme perspective, codes with low height, blurred codes, scratched codes, etc.
Integration of barcode reader and applicator system
The DataMan 500 communicates using Rockwell’s EtherNet/IP protocol and has a driver for Rockwell PLCs that simplifies the integration task. Just before the bottles are put on the conveyor, an operator uses a hand scanner to read the barcode on the label automatically entering the number into a database. The operator then places the bottle on the line. A photo sensor detects the bottle as it begins to move on the line. As the bottle moves down the line, the tax stamp is applied to the bottle. Another photo sensor is mounted on the line just before the barcode reader and provides a signal to the PLC every time a bottle passes by on the conveyor. The PLC sends a signal to the camera to begin capturing images. The barcode reader captures images until it finds and reads a barcode. Based on the time and
travel that has elapsed since the bottle was loaded on the line, the PLC knows which particular bottle was read by the barcode reader and stores the tax stamp barcode in the same database row as it had previously stored the label ID. If the DataMan 500 cannot find a code then it sends a signal to the PLC. The PLC then triggers a reject mechanism to remove the bottle from the line at a downstream station. “The reliability of the Cognex barcode reader is substantially higher than the other cameras we tried in this application,” Chen said. “It rarely fails to detect the label even on bottles with the most confusing backgrounds and difficult lighting conditions. The barcode reader played a major role in the success of this application which saves a huge amount of time that was previously spent applying labels, manually scanning labels, and inputting the tax stamp information. The customer is very happy with the performance of the system and we have not received a single service call on the barcode reader.”
Cognex UK Ltd 46 JULY/AUGUST 2014 | AUTOMATION Tel: +44 (0)1327 856040 Web:
www.cognex.com enter 824 /AUTOMATION
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