| 摘要 |
An optional device for reading and decoding bars of different reflectivity arranged in accordance with a barcode and adjoining one another. The device includes an optical scanning device for scanning the bars by a light beam, a sensor for receiving the reflected light beam and converting the latter into an electrical sensor output signal, a transition detector for detecting the level transitions of the electrical sensor output signal and a decoding device which decodes the scanned barcode on the basis of the output signals from the transition detector. The sensor output signal is fed to an amplitude averaging device and/or contrast averaging device, the output of which is connected to a decision device which controls the decoding device in such a way that reading and decoding of the barcode is carried out several times if the output signal from the amplitude averaging device and/or contrast averaging device is below at least a predetermined threshold value.
|
