Abstract: There is provided, in one preferred embodiment, a bar code reader which has a variable scan angle, with the amplitude of the scan angle initially being relatively small and then increasing in magnitude until a bar code is read. As the amplitude of the scan angle increases, the scan frequency is decreased, thereby keeping the scan rate across the bar code relatively constant. Consequently, for example, a high-density bar code may be read at either a close distance or a far distance without sacrificing resolution. Additionally, the reading of a selected bar code in the presence of other, closely-spaced bar codes is facilitated. In another preferred embodiment, the scan frequency is held constant and the clock rate in the bar code reader is increased with increasing amplitude of the scanning angle.

Abstract: A bar code reader head having an optical block with cavities formed therein into which various optical elements may be placed without the need for any adjustment thereof. A first illumination source, producing any desired spectrum of light, illuminates at least a portion of the bar code. A second illumination source may be provided to produce a second spectrum of light. Reflected light passes through a lens in front of which is an aperture slit parallel to the bar code bars. A channel is formed between the lens and a photodetector perpendicular to the light path. If both visible and infrared illumination sources are used, visible light is focused at the side of the channel toward the lens and infrared light is focused at the other side of the channel. In the channel is a template having at least one discriminator slit parallel with the slit in front of the lens. The width of the discriminator slit depends upon the widths of the bars to be read.