Brother Kogyo Kabushiki-Kaisha

Kazuhisa Ito

Hajime Suzuki

Yoshiharu Higuchi

Ikuzo Kondo

A sewing machine control device performs a closed loop control of an induction motor without using an encoder for detecting the motor speed. The control device includes an inverter for driving the induction motor, and controls the inverter output so that the actual speed of the motor is brought into coincidence with a target speed instructed from a speed instruction device. When the control device executes the inverter control, it uses not only the target speed fed from the speed instruction device but also a detection signal generated from a needle position detector that represents the position of a needle bar and the moving speed thereof.

Sewing machine control device with an inverter for controlling an

A sewing machine stopping control system brings a sewing machine from a high-speed operation to a stop without varying modes and with high stopping accuracy, for allowing the sewing machine to operate highly efficiently. According to the stopping control system, a motor is decelerated in response to a release of a foot pedal. At a time when a predetermined rotational speed or lower is detected, the deceleration operation is disabled regardless of a decelerating command BKON outputted from a speed command comparing circuit. Thereafter, when a predetermined needle position is detected, the deceleration operation is resumed. When a predetermined low speed is detected during the deceleration, the deceleration operation is again disabled. Thereafter, when a predetermined needle position is detected, the deceleration operation is again resumed so that the motor is completely stopped.

Method of controlling stopping operation of a sewing machine and system

In a sewing machine, when the depressed condition of a foot pedal is changed from a forward depressed condition for high speed sewing to a reverse depressed condition for thread cutting, a braking circuit decreases the rotational speed of the machine motor from a high speed to a low speed. The rotational speed is detected by an encoder. When the rotational speed detected by the encoder becomes a threshold medium speed or less, and a needle-down signal is generated from a needle position detector, the CPU of the sewing machine outputs a work fabric feed pitch control start signal to a work fabric feed pitch selector. The work fabric feed pitch selector reduces or nullifies the feed pitch of the work fabric. Under this condition, in response to the next needle-down signal, the CPU operates a thread cutting mechanism to cut the needle and bobbin threads.

Sewing machine with automatic thread cutter

A sewing machine having a needle thread cutting unit and a needle thread holding device for holding a cut leading end portiion of the thread drawn from an eye of a needle. The needle thread holding device includes a holding means provided at the pressure foot. The holding means is movable between a needle thread clamping position and a needle thread releasing position. The holding device also includes drive means connected to the holding means for selectively moving the holding means to one of the needle thread releasing position and the needle thread clamping position, pressure foot position detection means for detecting a position of the pressure foot, needle position detector for generating a needle position signal indicative of the upper needle position and the lower needle position, and control means connected to the pressure foot position detection means the sewing machine energization signal generating means and the needle position detector. The controlling means maintains the holding means at its thread clamping position when the pressure foot is at its non-operative position after cutting the needle thread. The controlling means also maintains the holding means at its clamp position during a predetermined number of stitches at a starting phase of a next sewing operation.

Needle thread holding device in sewing machine

A sewing machine including a mercury switch for detecting tilt of the sewing machine. When the tilt of the sewing machine is detected by the mercury switch, a machine motor of the sewing machine is inhibited from being driven. Accordingly, even if a foot switch for driving the machine motor is depressed under the tilted condition of the sewing machine, the machine motor is not driven, thereby improving the safety of the machine. Furthermore, when the sewing machine is tilted during driving of the machine motor, the inhibition of drive of the machine motor is canceled, and a driving speed of the machine motor is set to a low speed. Under this condition, an operator can easily adjust a fabric feeding device, a thread cutting device and a rotating hook.

Motor driving device for sewing machine

A sewing machine provided with a thread cutting mechanism and a needle thread tension release mechanism. Normally, the needle thread is subjected to a proper tension by a thread tension regulating mechanism. However, at an initial start-up period of the sewing operation, the needle thread tension is released by the tension release mechanism for a first predetermined period during which a needle thread loop is trapped by a loop taker. Further, the sewing machine is provided with a thread holding member for holding a leading end portion of the needle thread. The holding member is movable to its thread release position after elapse of a second predetermined period at the initial start-up period of the sewing operation. The first predetermined period is within the second predetermined period.

Growing community of inventors

Aichi, Japan

Kazuhisa Ito