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Easy PC controlfor machine vision

Upsher-Smith Laboratories uses off-the-shelf PC hardware for an all-in-one video capture/bar-code scanning inspection system to satisfy FDA labeling regs while keeping false rejects low.
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With new FDA labeling inspection regs slated to take effect in August pharmaceutical companies are now deploying automated inspection systems to replace manual inspection (see p. 18). The use of machine vision has become an integral part of many of these automated inspection systems. To many pharmaceutical packagers machine vision has meant custom software running on expensive dedicated hardware that is engineered specifically for automated inspection. However one pharmaceutical company Upsher-Smith Laboratories Inc. Minneapolis MN has harnessed the power of off-the-shelf desktop computing for optical character verification (OCV) and bar-code inspection tasks on its tablet bottling line. Upsher-Smith uses the line to fill its prescription-strength Klor-Con® potassium chloride extended release tablets as well as other products in high-density polyethylene containers that range in size from 60 cc up to 40 oz. Installed in June '96 as an upgrade to a previous inspection system the new system meets Upsher-Smith's three requirements: "We wanted a system that would give us extremely reliable results minimum false rejects and something easy to set up" says Brad Christenson manager of manufacturing services. The system consists of a scanner that verifies UPC bar codes on labels while they're still on the web; a video camera to verify the correct date/lot code; UV sensors to detect the presence of the label after application; and a second bar-code scanner to inspect an Interleaved 2 of 5 bar code on the outsert after it's applied to the top of the container. The inspection system dubbed Touchmaster Scan+ by its supplier Parish Automation (Manasquan NJ) runs on an industry-standard Pentium®-based personal computer running at a respectable 133 MHz. The benefits for Upsher-Smith are several: * Higher precision. The company's previous system could only detect the presence of a date/lot code; the new system can verify that each character of the 10-digit date/lot code is correct and unblemished within user-defined tolerances at Upsher-Smith's top line speeds of 100 bottles/min. (The inspection system can operate at speeds up to 220 bottles/min.) * Greatly reduced false rejects. "We specified a false-reject rate of less than 0.5 percent from all the inspection devices" says Christenson. "This system is giving us the reliability and the results we want." * Fast set-up and changeover. The PC equipped with a touchscreen display acts as a central control for all inspection components including bar-code scanners machine vision camera and UV sensors. Result: set-up before a production run takes no more than 10 minutes. "Had we gone with a separate vision system and then a separate scanner it would have required two separate reject stations for the bottles coming out of the labeler as well as two separate set-ups" comments Christenson. What it scans The first two inspections are performed while the label is still on the web prior to its application. After the five-digit lot code and five-digit expiration date (including hyphen) are hot-stamped onto the label the code is inspected by the camera. If even a single digit is incorrect or poorly printed using limits defined by Upsher-Smith the label is tracked as it's applied to the container which is then rejected off the line. The second inspection performed on the web is by an Accu-Sort (Telford PA) bar-code scanner that examines the UPC code on the label. One of three results will occur: a match a no-read or a no-match. A match means the bar code was read and that it correctly matches the code stored in the system's database for the particular product being packaged. A no-read means the scanner was unable to read the bar code which could be due to a missing or mis-aligned label on the web or poor print quality. Upon a no-read detection the label is tracked until it is applied to the container which is then rejected off the line. The third possibility is a no-match meaning the bar code has been read and it is incorrect. This is the most serious error immediately causing the labeler to stop and display an error message on the touchscreen display. This type of error message cannot be cleared by an operator. It requires a supervisor to enter a restricted password which is entered only after an investigation is complete to determine if a labeling mix-up has occurred. The previous system could not distinguish between no-match and no-read faults thus limiting its usefulness. As a final check ultraviolet sensors from Datalogic (Scotts Valley CA) sense the presence of the label on each bottle by detecting the UV inks and varnish used to print the label. Bottles without a detectable label are immediately rejected from the line. Bottles that pass the three inspections performed at the labeler will then have an outsert applied to the top of their closures. A second Accu-Sort scanner picks up the I 2 of 5 bar code printed on the outsert. The outsert scanner provides the same three inspection results as the labeler scanner. Containers that have either a no-read or no-match result are then rejected at a separate eject station. This prevents mix-ups not only between different outserts but even among different revisions of the same outsert. Christenson explains: "Every time we revise an outsert we change the I 2 of 5 code. So it is not possible to mix up a previous revision with a current version." Three consecutive faults at any of the system's four inspection devices will immediately shut down the labeler and display an error message on the touchscreen thus alerting the operator of a potential problem. After taking corrective action to fix the problem the line operator can then reset the system. The number of consecutive faults needed to trigger a shutdown of the system is user defined for each of the devices and can easily be changed in a password-protected menu option. One of the chief benefits of the system says Christenson is its fast set-up. Operators simply key in a date/lot code and select the product to be run from a menu. The computer calls up the appropriate bar-code information for comparison purposes from a database on the computer's hard drive. Then the operator "trains" the video camera by sizing and positioning a box on the video screen around the image of the date/lot code. After testing with known samples both correct and incorrect the system is ready to go. Total set-up: about 10 minutes says Christenson. Control without keyboard All operator input to the system is done via one central color touchscreen; there isn't even a need for a keyboard. All set-up can be handled by the line operator. "That's one of the key things that we like about it" says Christenson. "It's something that doesn't require a mechanic or someone else to come over and help with the set-up. The acceptance of the system by the people on the line was tremendous. Also the amount of time it took to train the line operators was minimal." Although the computer runs the vision and bar-code software and provides the central control for all inspection components it is connected to a PLC from Allen-Bradley (Milwaukee WI) that in turn communicates with the actual inspection components and the reject mechanisms on the packaging line. At the end of each run the system provides a printout for the production run that lists the total number of inspections for each inspection device; the number of matches no-matches and no-reads. "If we ever see a no-match on a report it would require an explanation and would be investigated" says Christenson. Finally the fact that the vision system doesn't require custom hardware has a significant effect on the economics of machine vision says Christenson: "I would say it's a very competitively priced system." The result is a system that gives Upsher-Smith the necessary performance in providing improved quality assurance while having a minimal drag on the packaging line's productivity with regard to false rejects. "The system reliably prevents any kind of labeling mix-up" concludes Christenson. "It gives us a cost-effective solution that provides a higher quality standard and firmly positions us to meet the new CGMP regulations for pharmaceutical labeling."

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