Autofocus bar code reader

摘要

A bar code reader includes a semiconductor laser diode as a source of an elliptical shape divergent laser beam and a shaping section for shaping the elliptical shape divergent laser beam to provide a shaped laser beam in the form of a circular shape collimating laser beam. A distance measuring section measures a distance to a bar code label and generates a distance information signal. A temperature sensor is attached to a casing of the shaping section. The temperature sensor detects the ambient temperature and generates a temperature information signal. A focal position controlling section conducts a focal position control in response to the distance information signal and the temperature information signal so that the shaped laser beam will have its focal position on the bar code label. A scanning section lights the bar code label with the shaped laser beam that has been subjected to the focal position control. A light intercepting section intercepts reflected light by the bar code label and generates an output indicative of the intercepted reflected light. A decoding section decodes the output. An outputting section outputs the decoded result to an external device. The shaping section includes a collimating lens, a first cylindrical lens and a second cylindrical lens, all of which have a short focal distance. <IMAGE> <IMAGE>