Patent ID: 8100068
Filing Date: 2012-01-24
Classification: D05B,D05D

Abstract:
1. A threader of a sewing machine, comprising: a threading shaft arranged near a needle bar for moving a supporting sewing needle vertically capable of moving vertically and supported for rotating around an axis; a threading hook having a hook portion fixed to a lower end portion of the threading shaft, and capable of being inserted into a needle hole of the sewing needle, and a first guiding portion for guiding the hook portion to the needle hole; a positioning member for regulating a lowermost position of the threading shaft to a position where the height of the hook portion matches that of the needle hole of the sewing needle; a first rotary mechanism for rotating the first guiding portion by a predetermined angle so that the hook portion is inserted into the needle hole of the sewing needle at a near lowermost point of the threading shaft; and a thread-guiding member for guiding a top thread to the hook portion near the lowermost point of the threading shaft, wherein the thread-guiding member comprises a thread-catching portion for catching a thread, and a second guiding portion for guiding the thread-catching portion toward the sewing needle, the threader further comprises a second rotary mechanism for rotating the second guiding portion by a predetermined angle so that the thread-catching portion is guided towards the needle bar and a thread caught by the thread-catching portion is guided to a position near a hook portion of the threading hook near lowermost point of the threading shaft; the first rotary mechanism and the second rotary mechanism rotate the threading hook and the thread-guiding member in opposite directions; the threader comprises a threading-leading member that is externally fitted or internally fitted to the threading shaft thereby being fixed to a body of the sewing machine, and that has a first cam hole and a second cam hole on a circumferential face, wherein the first rotary mechanism comprises the first cam hole, and a first cam shaft that is disposed on the threading shaft and that is fitted to the first cam hole, the second rotary mechanism comprises the second cam hole, and a second cam shaft that is disposed on the thread-guiding member and that is fitted to the second cam hole, and a direction in which the first cam hole is inclined is an opposite of a direction in which the second cam hole is inclined, a width in the vertical direction of the first cam hole at a near uppermost portion is larger than a shaft diameter of the first cam shaft, and a biasing member is disposed between the threading hook and the thread-guiding member so as to bias the threading hook and the thread-guiding member away from each other.