When the power switch or the corresponding equipment is triggered to electrify the scanner, the VLD emits a red laser beam, which is expanded through the beam expanding lens and reflected to the surface of the oscillating mirror to form a laser point on the bar code. When the mirror oscillates, according to the principle of optical reflection, the position of laser points on the bar code changes, and the mirror oscillates continuously, then a red laser line will be seen on the bar code, which is caused by the phenomenon of visual persistence.
The surface of the bar code is rough, and the reflection intensity of the laser spot on the bar code is different from that of the space. The diffuse reflected light is reflected on the reflector, and then reflected to the collector by the reflector. The collector collects light, filters stray natural light into the photosensitive diode, and generates photoelectric induction signal. After amplification, shaping and decoding, it becomes useful information and transmits it to the master. Machine.