| 摘要 |
<p>PURPOSE: To make an optical reader convenient to be used for read of information encoded with wide-range densities to improve the efficiency by making the diameter of diffused light at the point, where diffused light is brought into contact with optical encoded information, different between two different distances. CONSTITUTION: When a spacer 21 is attached relatively far ahead of the front end part of a housing 11 and the front end part of the spacer 21 is brought into contact with a surface S, the distance between a focus P and the surface S is relatively long, and the spot of light is large. This case is suitable for read of information encoded with a low density like a bar code printed by a dot matrix. Meanwhile, when the spacer 21 is shortened in the opposite direction on the housing and the front end part or the spacer 21 is brought into contact with the surface S, the distance between the focus P and the surface S is relatively short, and the spot of light is small. This case is suitable for read of information encoded with a high density like a small-sized bar code.</p> |
