| 摘要 |
<p>1461174 Sewing machine MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 25 March 1974 [23 March 1973] 13197/74 Heading D1G A sewing machine drivable at high and low speeds by a motor has a brake 14, 15 and a disc 16 having peripheral gaps which cooperate with means (photo electric as disclosed) to generate electrical signals, a switch 34 operable (by a treadle) to drive the motor at the high speed, a dynamic brake signal circuit 53 operable when the switch 34 is released to decelerate the motor to the low speed, a needle down position detector 60, a brake circuit operable by that detector to brake the motor to a standstill, a low speed signal generating circuit 31 operable by a second switch 38 to apply a low speed signal to the motor and a needle up position detector 61 for applying a brake signal to stop the motor. The needle-down and needle-up detectors may each comprise a monostable multivabrator 20 or a differentiator and the dynamic brake signal circuit may comprise a flip flop circuit 51 associated with the first switch and an 'AND' gate 41 coupled to the switch. Several patterns of disc 16 (Figs. 2, 5, 8 and 10 not shown) are disclosed. A further circuit outlet 40 operates a tension release, thread trimming and wiping devices not otherwise described.</p> |
