Writing instrument with ink quantity of level detecting function

摘要

A writing instrument with ink quantity or level detecting function which has an ink tube containing ink, and a float so arranged in intimate contact with the rear end surface of the ink in the ink tube as to be driven in contact with the rear end surface of the ink upon decrease of the ink in the ink tube. Further, a magnetic sensor is further provided externally at the writing instrument, while the float is formed of magnetic material. Thus, lack of the ink in the ink tube of this writing instrument can be readily detected.