OPTICAL INFORMATION READER

PROBLEM TO BE SOLVED: To protect a power supply circuit of an optical reader when using a general-purpose illumination unit.SOLUTION: By measuring values of current flowing into a general-purpose illumination unit 122 which cannot acquire device model information, a PWM control for intensifying the lighting intensity of a LED 80 is conducted (S102). In each lighting intensity which varied by PWM control, a comparator 126 compares a value of the current flowing into the general-purpose illumination unit 122 with a given maximum current value, and makes an interruption of current detection occur when the current value exceeds the maximum current value (S104). Then, the lighting intensity at the time of occurrence of the interruption is stored as the maximum lighting intensity in a memory M of a bar code reader 2 (S105). When the lighting intensity reaches the maximum value as a result of intensifying the lighting intensity of the LED 80 through the PWM control without occurrence of interruption (S103), the lighting intensity at this time is stored as the maximum lighting intensity in the memory M of the bar code reader 2 (S105).