| 摘要 |
A scanning projection light source for a barcode device includes a laser diode, a converging lens located in front of the laser diode, a first photo mask located in front of the converging lens having a round aperture formed therein, and a second photo mask located in front of the first photo mask having a second aperture formed therein. The second aperture has two arched light blocking tabs located at two lateral sides for partly covering the round aperture. The laser diode emits a light spot to the converging lens which transforms the light spot to a parallel light beam. The parallel light beam is projected to the first photo mask through the round aperture to become a round light spot which passes through the second aperture and become an output light spot having arched tangent sides. The arched tangent sides are approximate to straight lines at a close distance and will result in a high resolution, and become arched tangent sides at a longer distance for scanning a lower resolution barcode.
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