Being the symbol

摘要

PROBLEM TO BE SOLVED: To stably read a two-dimensional symbol by controlling electric charge storage time in an image pickup element based on the speed of shake of a case body to be detected. ;SOLUTION: A voltage corresponding to the speed of the shake of the case body 10 is outputted from an angular velocity sensor 40 disposed near a CCD 35 inside the case body to a case body shake detection circuit 41 and an analog voltage corresponding to an input value from the angular velocity sensor 40 is outputted to a comparator 42 in the case body shake detection circuit 41. The comparator 42 defines a reference voltage value S₂ set by a variable resistor Rv as a threshold value, compares the voltage value S₂ with the output voltage S₁ of the case body shake detection circuit 41, outputs a high signal, that is '1', when the output voltage S₁ is higher than the reference voltage value S₂ and outputs a low signal, that is '0', when the output voltage S₁ is lower than the reference voltage value S₂. Then, the electric charge storage time of a photodiode is set to be short in the case that the shake of the case body is large and the electric charge storage time is set to be long in the case that the shake of the case body is small.;COPYRIGHT: (C)1998,JPO