| 摘要 |
The proposed device for reading code bars (10) of a code combination (1) has for each of the code bars of a combination one display element (40), which consists of two parallel-connected light-emitting diodes, particularly a green light-emitting diode (41) and a red light-emitting diode (42), a transistor (43) driven by the level of the analog read-signal pulse (21) being connected in series with the green light-emitting diode (41) so that the forward resistance is small and the display current flows mainly via the green light-emitting diode (41) when the read code bar has good contrast, whereas with a weak contrast and correspondingly low drive to the transistor (43), the display current flows mainly via the red light-emitting diode (42). In this manner, the display changes from green to red when the contrast of the viewed code bar becomes weaker, which can be considered as a warning signal and indication of beginning unreliability of the scanning. <IMAGE>
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