| 摘要 |
A bar code reader reads a bar code by scanning a laser beam on a screen on which the bar code is displayed. The bar code reader has a beam scanning device for scanning the laser beam irradiated from a laser oscillator. The beam scanning device has a polygon mirror which is rotated and driven around an axis. The polygon mirror forms at least two kinds of flat reflecting surfaces for respectively scanning the laser beam along with the rotation of the polygon mirror. Scanning angles by the reflecting surfaces are twice as large as opposite angles to which the reflecting surfaces correspond respectively. The laser beam is scanned at two or more kinds of scanning angles, that is, scanning angles and which are respectively adapted to the long and short bar codes. Therefore, the bar code can be accurately read irrespective of a length thereof.
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