Patent ID: 8225727

Claim:
A tufting machine comprising: a tufting head translatable within said tufting machine in X- and Y-directions with respect to backing fabric by means of a movement system, which tufting head comprises a tufting mechanism having a cyclic mode of operation; a hollow needle mounted in the tufting mechanism that is moveable relative to a cooperating foot in a reciprocating manner to insert a tuft of yarn into backing fabric in each cycle; a yarn supply mechanism mounted in the tufting mechanism and operable to supply a length of yarn to the hollow needle in each cycle; and a yarn cutter mounted in the tufting head that is selectively operable to cut the length of yarn in selected cycles to produce loop or cut pile; and a computer-operated motion control system adapted to read a machine-readable tufting design pattern comprising a series of vectors and associated control codes and, in response thereto, to generate signals to drive the tufting head (a) to operate the tufting mechanism and reciprocate the hollow needle to insert tufts into backing fabric; (b) to operate the movement system and move the needle across a two-dimensional plane defined by said X- and Y-directions while inserting tufts in accordance with the vectors; (c) to lift and lower the foot in accordance with respective control codes; (d) to selectively operate the yarn cutter in accordance with respective control codes; and (e) to operate the yarn supply mechanism to selectively provide different lengths of yarn in different cycles in accordance with respective control codes, and so to individually vary the pile height of both cut and loop tufts; wherein the yarn supply mechanism comprises a yarn feed motor; a yarn feed roller arranged to be rotatably driven by the yarn feed motor; and a controller to receive signals from the computer-operated motion control system indicative of the length of yarn for a given tuft and in response to determine the speed of revolution of the yarn feed motor; and wherein the yarn feed motor is a stepper motor driven in an open loop configuration.