Application Stories - Sensors and Instruments in Industrial Automation

Pharmaceutical labels are often prepared in roll form; ie, labels printed on a backing and wound onto a core. In this form, labels are easily distributed, stored, counted and applied.

Accounting for labels is one technique commonly employed to insure that pharmaceutical products are properly labeled. Label rolls are inspected for correct label and count. Barcode readers are used to read codes from labels to insure that each label on a roll is correct. Counting sensors are used to verify the number of labels on a roll.

On use, labels are counted, batched and applied. Unused labels are re-counted and returned to stock. Pharmaceutical manufacturers must account for all labels: the number of labels issued less the number returned to stock must be equal to number of items labeled plus authorized discards or scrap.

Counting is mechanized and automatic. A motorized label counting table mounts the label core, unwinds the roll of labels through a set of counting sensors, missing label detectors, barcode readers and strobe lights to insure that each roll contains a known quantity of labels, the correct labels (as determined by a barcode printed on each label).

Sounds straightforward, but there are complications which raise the need for smart instrumentation.

First, drive motors must use soft starts and stops so as to prevent breakage of the label backing. Instrumentation controls drive motors in response to operator commands.

Second, the label web must be drawn through the inspection station at constant speed so that barcode readers inspect each label uniformly. Recall that for counting and inspection, the label roll is being unwound from its original core and rewound on a new take up core. As the take up core receives labels, it expands in diameter. A constant speed motor would pull labels at a faster rate. To accommodate this effect, label inspection instrumentation measures the label inspection rate and adjusts the motor speed to keep the rate constant.

Label inspection instruments do more than count labels. In addition, the instrumentation triggers barcode readers, fires strobe lights for visual inspection or photography, controls motor speed for constant inspection rate.

For information on Label Counting Tables which use Scanning Devices instrumentation contact:

• H. B. Registration Corporation
• 1711 West Elizabeth Ave.
• Linden, NJ 07036
• 800-486-3311
• Link to H. B. Registration

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