END DETECTOR OF ROLLED PAPER

摘要

PURPOSE:To detect the end of a rolled paper ignoring uneven coating of a mark accurately by continuously the detecting and memorizing end marks provided on the rolled paper during the movement thereof to discriminate with the contents detected and memorized when it is at rest. CONSTITUTION:A white mark 21 is applied at the end of an ink doner sheet 2 as roll-shaped recording medium. The presence of the mark 21 is always detected with light emitting diode 14 and a photodiode 12 during the recording operation of a printer. Upon the detection of the mark 21, an integrator 16 integrates a detection signal 15 while the ink doner sheet 2 moves by one sheet in the direction of subscanning. The integration signal 18 is inputted into a peak hold circuit 19 to vary the potential VS appearing on the source S of a transistor 19D. A binary coding circuit 31 compares the voltage VS with the reference voltage V0 and outputs an end discrimination signal 32.