| 摘要 |
PURPOSE:To read information accurately by providing a means crossing an optical path of a radiated laser beam and a beam waist position changing member so as to scan an object to be scanned even if the object to be scanned exists nearly or remotely. CONSTITUTION:A rotary holding member 29 acts like a means allowing a beam waist position changing optical member to cross the optical path M of a radiated laser beam P. Then number of reflecting planes 5a of a polygon mirror 5 is selected to be N and the member 29 is turned once as to one rotation of the mirror 5, then the object to be scanned is scanned by N/2 times every time the collimated plate 32 crosses the optical path M once. Thus, the plate 32 is in the saving position from the optical path M during the period of a half rotation of the mirror 5 and in directing a bar code reader to the object to be scanned in existence nearly (remotely), the scanning of N/2 times is applied to obtain a read signal. In this case, even when the bar code reader is directed to the object in existence remotely (nearly), only noise is obtained. Thus, the information is read accurately even if the object to be scanned exists nearly or remotely.
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