Thread consumption detecting apparatus for a sewing machine

A thread consumption detecting apparatus, comprising:

• an axial supporting shaft disposed on an arm, the axial supporting shaft extending perpendicularly to a direction of a transfer route of a thread, the transfer route traveling from a thread guide to an eye of a needle;
• a detector lever including an intermediate portion, a loop-shaped thread-contact end, and a base end, the intermediate portion fitted idly around said supporting shaft, the loop-shaped thread-contact end extending from the intermediate portion in one direction, the base end extending from the intermediate portion in another direction, the detector lever disposed so that the thread passes outside the loop-shaped thread-contact end, the detector lever being capable of swinging about the intermediate portion so that a swinging stroke thereof interferes with a thread-transfer-route variation range resulting from a fluctuation in tension of the thread;
• detecting means for detecting the base end of said detector lever on approach when said detector lever is swung by the tension of the thread, and for outputting a detection signal;
• urging means for urging said detector lever in one swinging direction so that the base end of said detector lever approaches said detecting means;
• and
• judging means for judging whether the thread is consumed or not in accordance with the detection signal output from said detecting means.