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

摘要

A photo-transistor 31 is arranged to overlap with a light emitting diode 33 in a longitudinal direction of a barcode reader 7 and on a side, to which the light emitting diode 33 emits light. In this case, the photo-transistor 31 and the light emitting diode 33 are arranged on the same optical axis. As the result, since depth of focus and depth of field overlap with each other in the optical axial direction, it is believed that resolution in reading a bar-code is secured in wide range in the optical axis direction. The depth of focus includes an image point when the light emitting diode 33 is positioned at an object point. The depth of field includes an object point when the photo-transistor 31 is positioned at an image point.