Optical sensing of multicolour documents

摘要

The optical sensing is used on documents that have a multicoloured pattern of, for example, red, green and blue lines. A single sensor is used to receive an input via a filter that has a bandwidth so the most appropriate range of the spectrum of the colours is selected. In the case of the three colours 1,2,3 the bandwidth is between approximately 520 to 580 nm. This results in the sensor responding to almost the same brightness value.