| 摘要 |
PURPOSE:To prevent outer light from making incident on a photodetecting element and to give a low bright light source having a wide wavelength distribution by limiting a range where a photodetecting optical system watches a pattern face. CONSTITUTION:A scanning optical beam F scans a bar code face from a point B to a point B' with the aid of the rotation of a rotary multiphase mirror 4. Reflected light X from the bar code face 5 is so set that light beams in the range AA' can make incident on the photodetecting element 8 through a lens 6. Namely the pthotodetecting optical system composed of the photodetecting element 8, the lens 6, a mirror 7 and the rotary multiphase mirror 4 watches the range AA' including the bar code face irradiating point of the optical beam F. The reason why the photodetecting optical system does not narrow the range AA' where it watches the bar code face up to the size of the bar code face irradiating point of the optical beam F is that a shift occurs between the optical beam irradiating point and the range AA' during scanning due to sight differences on the bar code face of a scan optical system and the photodetecting optical system. Accordingly a space is given to the range AA' so that the point where the photodetecting optical system watches hardly deviates from the irradiating point of the optical beam due to the shift. As a result, the influence of outer light can be reduced.
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