Tape unwinding device with self-locking function

A tape unwinding device with a self-locking function, wherein the device comprises:

• an outer shaft connected to a mounting frame to rotate, a tape roll sleeving the outer shaft so as to be fixed relative to the outer shaft;
• a disk gear fixedly connected with the outer shaft;
• a shifting card connected to the mounting frame to rotate, a first torsional spring being mounted between the shifting card and the mounting frame, and the shifting card being pulled by a torsion of the first torsional spring to swing to the disk gear, so that the shifting card swings to be inserted into a toothed groove of the disk gear;
• and
• a swing arm connected to the mounting frame to rotate, one end of the swing arm being provided with a driving roller, and a tape passing by the driving roller after being pulled out, so that the tape drags the driving roller and drives the swing arm to swing to a direction away from the shifting card;
• wherein one side of the swing arm is further provided with an insert, and when the tape is not pulled out, the swing arm swings until the insert supports against the shifting card to be away from an end inserted into the toothed groove, so that the shifting card swings to be inserted into the toothed groove.