Light-beam scanning apparatus

摘要

Light-beam scanning apparatus mainly used for a bar-code reader in a point-of-sale system to identify sold articles. The apparatus includes a light-beam emitting device, a hologram disk having a plurality of hologram segments with different diffraction characteristics mounted along its circumference and being rotated at a predetermined speed, and a deflecting device for directing the emitted light beam from the light-beam emitting device to one side of the hologram disk in a first direction. The scanning apparatus has a first mirror group including a plurality of mirrors placed in a second direction corresponding to the other side of the hologram disk, each of which mirrors is arranged to receive a diffracted light beam from a corresponding hologram segment, and a second mirror group including a plurality of mirrors, each of which mirrors is placed to receive a light beam reflected by a corresponding mirror of the first mirror group and to reflect the incident light beam to a predetermined space positioned in the first direction where an article attached with a bar-code label is moved. In the apparatus, a light path from the other side of the hologram disk to the predetermined space has a predetermined length to form a predetermined scanning light pattern in the space.