BAR CODE READER, OPTICAL MOUSE, AND BAR CODE READING METHOD

摘要

A phototransistor (31) is arranged to lie over a light emitting diode (33) in the longitudinal direction of a bar code reader (7) and on the side, to which the light emitting diode (33) emits a light. In this case, the light emitting diode (33) and the phototransistor (31) are arranged on a common optical axis. It is, therefore, possible to estimate that a focal depth containing an image point at the time when the light emitting diode (33) is positioned at the object point, and an object depth containing the object point at the time when the phototransistor (31) is positioned at the image point, overlie in the optical axis direction, so that the reading resolution of the bar code can be retained over a wide range in the direction of the optical axis.