| 摘要 |
<p>PURPOSE:To improve the readout precision of a scanner which reads bar codes optically by causing light from a light source to strike a spherical lens through a multifocus lens and increasing the depth of focus, and converting reflected light from a bar code photoelectrically. CONSTITUTION:At the fitting part 5 of a cylindrical hollow body 1 having an opening part atop, a light emitting diode 6 is provided and an emitted light beam is passed through a Fresnel lens 7 and then passed through different optical paths corresponding to respective ring belts 7a. Some of them illuminate the spherical lens 4 directly and the remaining beams are focused and then strike the spherical lens 4 by adjusting the position of the Fresnel lens. Therefore, plural adjacent focuses are obtained on an optical axis before the lens 4. A bar code is positioned at one of those focuses and its reflected light travels along the optical axis and is converted photoelectrically by a photodiode 9, whose output signal is led out through a lead line l. Thus, the bar code is discriminated precisely.</p> |
