Automatic range adjustment techniques for stand-mountable bar code scanners

摘要

By automatically adjusting the object detection mechanism of a bar code scanner from a long range mode of operation to a short range mode of operation, the scanner will remain capable of detecting and decoding bar codes even if the object detection mechanism repeatedly detects the presence of a background object. The techniques of the present invention commence when the bar code scanner is placed in a position such that the scanner's object detection mechanism repeatedly detects a background object such as a counter top or conveyer belt. The object detection mechanism is set to the long range mode of operation if it is not already so set. In the case of a stand-mounted scanner, a test is performed to ascertain whether or not the scanner is in its stand, and the method will only proceed once the scanner is resting in the stand. Next, the scanner is programmed to wait for a predetermined amount of time, after which the operational mode of the object detection mechanism is changed from the long range mode to the short range mode. At this time, the object detection mechanism no longer detects the presence of the background object. The scanner will now detect any new objects that enter the field of view of the object detection mechanism, and attempt to read any bar codes which may be present