INK SHORTAGE DETECTION DEVICE OF INK-JET RECORDING APPARATUS

摘要

PROBLEM TO BE SOLVED: To surely detect when ink is empty without considering aging of a detecting means for detecting a density of a mark and a density of a white part. SOLUTION: Threshold values of densities of a black mark M and a white part are suitably set following changes of the densities detected by an ink end mark detection sensor 17. The threshold values are automatically re-set a predetermined time after the threshold values are set or every time it is instructed to detect the presence/absence of ink after the threshold values are set. Further, the threshold values are automatically re-set every time the printed number of recording papers reaches a predetermined value after the threshold values are set.