Roll paper terminal end detecting unit and method

A method for detecting the terminal end of roll paper rolled around the core in the roll paper type recording/printing unit to provide a roll paper terminal end detecting unit, the method comprising the steps of:

• providing a roll paper core supporting roll paper with a roll paper supporting surface made darker than the roll paper, one of an outer roll surface of said roll paper and said paper roll supporting surface forming a measured surface;
• providing a photo sensor with an element for emitting light and for detecting an intensity of reflected light;
• providing a photo sensor bearer support, said photo sensor being connected to and supported on said bearer support to direct said photo sensor toward said measured surface;
• maintaining a distance between the photo sensor and said measured surface so the photo sensor follows the reduction in roll diameter of the roll paper based on said distance by providing a pinch roller in contact with said measured surface, said pinch roller being connected to and supported by said bearer support and being disposed adjacent to said photo sensor;
• pressing said bearer support with a spring to press said pinch roller, by spring force, on to the surface of turning roll paper;
• and
• detecting the terminal end of roll paper by detecting a change in the intensity of reflected light which is detected by the photo sensor, between said outer roll surface of said roll paper and said roll paper supporting surface.

A roll paper terminal end detecting unit for detecting the terminal end of roll paper in a roll paper type recording/printing unit, the detecting unit comprising:

• a core for supporting the paper roll, the outside surface of said core being darker than the roll paper, one of an outer roll surface of said roll paper and said paper roll supporting core surface forming a measured surface;
• a bearer support;
• a pinch roller connected to and supported by said bearer support, said pinch roller engaging the surface of the paper roll to follow the surface of the paper roll during a feeding out of paper to follow a reduction in roll diameter of the roll paper;
• a spring for pressing said bearer support to press said pinch roller against the surface of the roll paper;
• and
• photo sensor means for detecting an intensity of reflected light for detecting the terminal end of the roll paper through the change in the intensity of reflected light between said outer roll surface of said roll paper and said outside surface of said core, said photo sensor being connected to and supported on said bearer support to direct said photosensor toward said measured surface, said photo sensor being maintained a spaced distance from said measured surface by said pinch roller.