| 摘要 |
PURPOSE:To always read the optical information with high accuracy by changing periodically the time interval of the read clocks produced from a read clock generating means based on the prescribed time information. CONSTITUTION:The generating time interval of the read clocks supplied to an image sensor (a) from a read clock generating means (c) is changed periodically based on the time information set previously. Thus the information is read when the generating time interval is increased in such a case the input level of the optical information is too low due to the soil of a label, for example. As a result, the level of the output electric signal is raised up owing to the sufficient store time and therefore the information is read with higher accuracy. While the information is read at the time of the read clock generating time interval is shortened in case the input level of the optical information is too high due to the effect of the external light, etc. Thus the level of said electric signal is reduced owing to a short store time and therefore the information is read accurately with no saturation.
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