Sewing machine lower thread monitor

摘要

The appts. to monitor the lower thread, in a double lock-stitch sewing machine, has a data carrier marking (22) on the flange of the bobbin (13) to show the actual lower thread supply in defined data form. The data carrier marking (22) is a magnetic strip shaped as a sector or a rectangle, or it can be circular, concentric to the bobbin (13) centre, as a round magnetic track. A mark at the bobbin (13) can show the number of thread windings in contrast to the outer side of the bobbin flange (19) and the data carrier (22). The data carrier (22) is a hybrid circuit as a transceiver. The sensor has a read/write head (27) directed at the data carrier (22) on the bobbin (13) from a swing mounting on a base plate (3), and a similar assembly at the sewing machine bobbin winder. The read/write head (27) is moved (33) towards the data carrier (22) so far as to give an unhindered thread loop between an end side of the looper and the read/write head (27). The sensor assembly can be in a separated station at the looper, and a further station at the bobbin winder. The separate sensor stations can have a read/write head (27) aligned at the bobbin (13) mark (22), with a write head as a second sensor and a read head working with a mark on the handwheel connected to the second sensor. The lower thread consumption is shown by a signal, passed to the control. The bobbins can be given code identities to be matched at external memories to generate the usage and remaining supply data.