| 摘要 |
PURPOSE:To attain an exact reading even when a distance between a sensor and the printed surface of a bar code is changed by discriminating a case as an effective data only when an AD-converted value against a threshold value is generated continuously within a regulated range of a value decided as a black bar. CONSTITUTION:A lamp 1 which illuminates a bar code surface printed on a form, and a bar code reading part consisting of a sensor 2 which inputs reflected light from a form surface are provided, and a sampling is performed synchronizing the output signal from the sensor 2 with the carrying speed of the form. In other words, a signal from the sensor 2 is passed through an amplifier 4, and is sampled 5 with a form carrying motor/encoder. And a data is converted by an AD converter 6 and a converted data is stored at a microprocessor 7. At such a time, as a decision logic for the black bar, a count value is four or less, and also, by deciding it as the presence of the black bar only when the count value continues in two times or more, or in six times or less, the bar code can be judged exactly even when a dispersion, etc., in the distance between the sensor and the form surface is present.
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