| 摘要 |
<p>A system evaluates the data derived from scanning a circular bar code element. The elements in the circular bar code extend radially outwardly from a center of the label, and their width varies along the radial direction. For that reason, should a circular bar code reader be offset relative to the center of the label, it is possible that the circular bar code reader would develop analog signals of the width of elements that vary within a single scan. At one location on the label, an offset reader may read one analog signal for a wide element, and at another location may read a wholly different signal for a wide element with an identical width. To address this problem, an element under evaluation is compared to adjacent elements, and a determination is made of whether the particular element is wide or narrow. Any offset will cause minimal variation in adjacent elements. Several methods for using this basic concept are disclosed. The invention also provides an improved method of switching between digital signals indicating dark or light elements. The analog signal is separated into two branches with a first branch being directed into a delay. The second branch identifies a peak value for the particular element, and then develops a signal proportional to that peak value. The delayed signal is then compared to that proportional signal, and when the delayed signal crosses that proportional signal, the digital signal is switched between the dark and light readings. <IMAGE></p> |
