Yarn feeding device for flat knitting machine

A yarn feeding apparatus of a flat knitting machine that supplies a knitting yarn to knitting needles performing a knitting operation based on knitting data while moving a yarn feeding member in a width direction of a knitting fabric, comprising:

• a knitting yarn sending mechanism that is provided on a supplying path of a knitting yarn and that sends out the knitting yarn to the yarn feeding member;
• a buffer rod that is provided on a path on which a knitting yarn is supplied from the knitting yarn sending mechanism to the yarn feeding member, that can be displaced by swinging around a base end side, that pulls partially the knitting yarn out of the path when a front end side thereof is displaced to one side by swinging, and that returns the knitting yarn to the path when the front end side is displaced to the other side by swinging;
• a spring that applies a force to the buffer rod in such a manner that the front end thereof is displaced to the one side by swinging so that the knitting yarn of a predetermined length is pulled out of the path with a predetermined tension of the yarn;
• a sensor that detects a swinging displacement state of the buffer rod using as a reference an origin that is a position of the front end side when the knitting yarn is pulled out of the path only for the predetermined length, and that derives a signal showing a detection result;
• and
• control means for performing a pattern analysis based on knitting data, for calculating a theoretical value of a knitting stitch loop length to be knitted for each knitting needle, for controlling the knitting yarn sending mechanism in a necessary yarn sending mode in which the knitting yarn is sent out in synchronization with a movement of the yarn feeding member, and for correcting an element affecting a predetermined knitting switch loop length before and after knitting one course of a knitting fabric in such a manner that an error between a length of a knitting yarn supplied for one course actually measured by the sensor based on an angle change in the swinging displacement of the buffer rod and a theoretical value of the knitting stitch loop length for one course is absorbed.