초록 ▼

Scan units scan top surfaces of articles A and B with a laser beam as they are transported by a conveyor belt. The scan units are capable of changing the focal position of the laser beam within a predetermined range. Changing the focal position of the laser beam requires a predetermined response tim

Scan units scan top surfaces of articles A and B with a laser beam as they are transported by a conveyor belt. The scan units are capable of changing the focal position of the laser beam within a predetermined range. Changing the focal position of the laser beam requires a predetermined response time. The heights of articles A and B are detected by a height detection unit in an amount of time equal to or less than the response time before they are scanned by the laser beam. When the heights of the articles as detected by the height detection unit change, a control unit will change at predetermined time intervals the focal position of the laser beam that is generated by each of the scan units. This allows the top surfaces of articles A and B, which are transported at short time intervals, to be scanned efficiently with the focused laser beam, permitting the efficient reading of bar codes and any other symbols that are formed on the top surfaces of articles A and B.

대표청구항 ▼

An optical scanner for scanning objects with informative symbols upon their surface, comprising: a plurality of scanning means for reading said informative symbols on one of said objects with scanning light when said one of said objects is disposed within a predetermined scan region, a focal positio

An optical scanner for scanning objects with informative symbols upon their surface, comprising: a plurality of scanning means for reading said informative symbols on one of said objects with scanning light when said one of said objects is disposed within a predetermined scan region, a focal position of said scanning light capable of being varied independently in each said scanning means within a predetermined response time; means for transporting said objects in a successive fashion through said scanning means; first means for detecting a height of said objects as they are transported by said transporting means, said first detecting means positioned at a predetermined distance from said plurality of scanning means so that an amount of time required to transport said objects from said detecting means to said predetermined scan region is greater or equal to said response time of said plurality of scanning means; and means for controlling said focal position of said scanning light in response to said first detecting means so as to provide an accurate reading of said informative symbols by said plurality of scanning means.