Matsushita Electric Industrial Co., Ltd.

Takeshi Morofuji

Shigeo Neki

Nozomu Shinozaki

Nobuho Shibata

Norio Umezawa

Tutomu Seri

A sewing machine controlling apparatus which starts and stops a sewing machine or controls its speed in accordance with the position of an adjusting means, e.g. - control pedal, for setting a sewing machine speed. The sewing machine speed, as controlled by the controlling apparatus is independent of the influences caused by changes in the pedal position signal P.sub.A through the vibrations of the machine or through the variations in a power-supply voltage. A smooth speed switching operation, which is free from speed variations, can be realized even at a stepped switching point of the machine speed control pedal.

Sewing machine controlling apparatus

A sewing machine controlling apparatus which starts and stops a sewing machine or controls its speed in accordance with the position of an adjusting means, e.g. control pedal, for setting a sewing machine speed, as speed. The sewing machine controlled by the controlling apparatus is independent of the influences caused by changes in the pedal position signal P.sub.A through the vibrations of the machine or through the variations in a power-supply voltage. A smooth speed switching operation, which is free from speed variations, can be realized even at a stepped switching point of the machine speed control pedal.

The circuit arrangement comprises a speed control system responsive to a speed signal indicative of the rotational speed of an arm shaft driving the sewing needle in the same manner as in known arrangements. Although the circuit arrangement operates in the same manner as in the known arrangement when a foot pedal is other than a neutral position, once the foot pedal is released to be in the neutral position, particularly provided speed setting data is used where the speed setting data value decreases as the rotational angle of the arm shaft increases. With this arrangement the sewing machine is capable of operating at a speed higher than conventional one during needle positioning with the speed being sufficiently reduced just before the needle is stopped. Thus a time length required for the last stitch has been remarkably reduced, providing efficient sewing work without deteriorating positioning accuracy. The sewing machine speed damping curve slope may be manually selected so that a user can set a desired positioning time. Furthermore, by selecting a needle position signal, the needle may be stopped at either at an uppermost position or a lowermost position.

Circuit arrangement for controlling sewing machine speed and for

Disclosed is a variable DC voltage device wherein one terminal of a DC power supply, a switch, a first coil of a transformer, a second coil mounted on a core of the transformer with the same polarities with those of the first coil, a diode for preventing a shortcircuiting of the DC power supply when the switch is closed and the other terminal of the DC power supply are connected in series in the order named; a load is interconnected between the junction between the first and second coils and the other terminal of the power supply; and a compensation circuit is provided for restoring to an initial state the flux variation caused when the switch is closed, whereby the load is controlled by the alternate opening and closing of the switch.

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Hirakata, Japan

Takeshi Morofuji