Sensor for identifying marks on a ribbon

The present invention relates to the use of an optical sensor for identifying marks on a printer print ribbon, or transfer ribbon. The sensor provides a reliable and accurate signal indicating that particular marks on the ribbon have been sensed using low cost light sources and optical sensors. A reflective type light sensitive sensor assembly is used for sensing the position of marks on a surface moving past the sensor. A typical showing is in relation to sensing marks on a ribbon used during printing operations, or lamination operations. The sensor assembly includes a LED light source that has a central axis, and a light sensitive transistor or sensor mounted in a single housing, with the housing oriented so that the axis of the light from the LED is inclined at an acute angle relative to the surface of the ribbon. The axis is at an angle other than perpendicular or near perpendicular to the surface. The marks used for identification are light diffusing marks, such as white marks or strips that will provide adequate reflection of light back to the light sensitive transistor or sensor forming part of the sensor assembly.