JPS6151172U - - Google Patents

Description

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts, Figure 2 is a block diagram of the electric circuit, and Figure 3 is the operating circuit 28 in Figure 2.
4 is a block diagram showing details of the second setting device 24 in FIG. 2, FIG. 5 is a time chart, and FIG. 6 is a flow chart showing the relationship between the up/down switch and the coefficient counter. It's a chat.

Claims (1)

[Claims for Utility Model Registration] Disposed on the needle thread path between the thread take-up and the needle thread supply source so as to be spaced apart from each other at the front and the front in the needle thread supply direction, and passed through the needle thread through electromagnetic force when energized. Two holding means 6 and 7 act on the needle thread so as to hold it in an impossible manner and release it so that the needle thread can pass through when no current is applied, and the needle thread path between the two holding means is periodically changed by a certain amount. A feed-out body 12 that operates in synchronization with the thread take-up so that the length of the path increases at a time other than the time when the needle thread tension is tensioned by the thread take-up and then becomes the shortest by the time the needle thread thread tension is tensioned by the thread take-up; A first position detection device 17 detects a specific rotation angle of the main shaft corresponding to the time when the needle is located below the top surface of the bed and generates a first position signal; A feed-out detection device 27 detects the amount of thread that has been drawn in and generates a thread amount signal corresponding to the amount of thread that has been drawn in, and a feed-out detection device 27 that detects the amount of thread that has been drawn in and generates a thread amount signal corresponding to the amount of thread that has been drawn in. A setting device 20 that generates a corresponding setting signal, and a comparison circuit 27 that compares the yarn amount signal with the setting signal and generates a matching signal when they match, The holding means on the balance side is de-energized, the holding means on the balance side is energized, the needle thread is fed out from the supply source between both holding means in conjunction with the feeding body, and the holding means on the supply source side is energized when a coincidence signal is generated. Then, the needle thread is prevented from being fed out thereafter, and the holding means on the thread take-up side is de-energized, so that a set length of needle thread is drawn out from the supply source in advance and supplied to the thread take-up each time one stitch is formed. A needle thread supply device of a sewing machine includes a second position detection device 18 which is arranged in relation to the main shaft and which detects a specific rotation angle of the main shaft corresponding to the tensioning period of the needle thread by the thread take-up and generates a second position signal; a control circuit that makes the current supplied to the holding means on the supply source side during the period from when the needle thread length is paid out until the second position signal is generated smaller than the supplied current after the second position signal is generated; A needle thread supply device for a sewing machine, characterized by comprising: