| 摘要 |
<p>In the preferred embodiment of a bar code scanning or reading apparatus disclosed and described the apparatus comprises a laser diode 32 (figure 16) as the radiation source for the beam scanning the bar code. A beam deflector 22 is provided for scanning said beam along a scan path a - b in a nominal or focal plane 92 containing the bar code to be read. Said beam deflector comprises at least one facet 24 arranged for being swivelled in a direction corresponding to the desired scanning path a - b of the beam in the nominal plane 92. Preferably, the beam deflector may be a polygon 22 having a plurality of light deflecting or reflecting facets 24, and may be arranged for continuous rotation. There are structural means such as radial ribs 28 extending radially from the axis of rotation of said polygon-beam deflector corresponding to, and preferably defining, said facet or plurality of facets in successive sectors of the deflector. Optoelectronic means 30 are responsive to light interrupted by the rips 28 and generate a control signal 110 which gates on and off the power supplied to the laser light source 32. The arrangement is such that the laser source will be enabled to generate the beam only within the confines of the scan path a - b. The duty cycle of the laser is thus reduced, thereby conserving power. As in bar code scanning or reading apparatus in general, and in portable hand-held scanners in particular, the source which provides the scanning beam such as the laser diode 32, is the element of the system which consumes the most power, saving power consumption by the scanning beam generating source is a major factor defining the live of batteries and the length of time of reliable operation with a given battery set or battery charge, and before the battery will have to be replaced or recharged. <IMAGE></p> |
