Abstract: A sewing machine according to the present invention includes: an upper shaft that drives a needle and a balance; a lower shaft that drives a hook and a feed dog; an upper and lower shaft belt that synchronizes rotation of the upper shaft with rotation of the lower shaft; and an idler unit that pushes an idler into the upper and lower shaft belt to change a tension side belt length, in which the idler unit includes a transmission mechanism connected to the upper shaft or the lower shaft, and a rotating body mechanism provided with the idler and having a rotating body that rotates in synchronization with the upper shaft or the lower shaft by the transmission mechanism, and a pushing amount of the idler into the upper and lower shaft belt is changed according to rotation of the rotating body.

Abstract: In a needle plate, a needle plate hole is configured to include a hole-side cutting side that cuts a cutting target object together with a blade portion, and a relief side that allows a cut portion of the cutting target object to escape. Specifically, the needle plate hole has the hole-side cutting side that shears the cutting target object together with a blade-side cutting side of the blade portion, and the relief side that forms a gap between the blade portion to be inserted and the relief side. In this manner, in the former stage of cutting processing, the cutting target object can be cut by the hole-side cutting side and the blade-side cutting side.

Abstract: In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

Abstract: A sewing machine according to the present invention includes: an upper shaft that drives a needle and a balance; a lower shaft that drives a hook and a feed dog; an upper and lower shaft belt that synchronizes rotation of the upper shaft with rotation of the lower shaft; and an idler unit that pushes an idler into the upper and lower shaft belt to change a tension side belt length, in which the idler unit includes a transmission mechanism connected to the upper shaft or the lower shaft, and a rotating body mechanism provided with the idler and having a rotating body that rotates in synchronization with the upper shaft or the lower shaft by the transmission mechanism, and a pushing amount of the idler into the upper and lower shaft belt is changed according to rotation of the rotating body.

Abstract: In a sewing machine, a plurality of needle plate holes are formed in a needle plate. The needle plate holes are arranged at positions respectively corresponding to a plurality of blade-side rotation positions of a cutwork blade. In this manner, the needle plate hole is formed in a shape corresponding to a shape of a blade portion, and a direction of the needle plate hole can match a direction of the blade portion that is arranged above to face the needle plate hole. Specifically, a linear hole-side cutting surface corresponding to a blade-side cutting surface of the blade portion is formed in the needle plate hole, and the blade-side cutting surface and the hole-side cutting surface can be arranged to face each other in a direction orthogonal to both the surfaces in a plan view.

Abstract: In a needle plate, a needle plate hole is configured to include a hole-side cutting side that cuts a cutting target object together with a blade portion, and a relief side that allows a cut portion of the cutting target object to escape. Specifically, the needle plate hole has the hole-side cutting side that shears the cutting target object together with a blade-side cutting side of the blade portion, and the relief side that forms a gap between the blade portion to be inserted and the relief side. In this manner, in the former stage of cutting processing, the cutting target object can be cut by the hole-side cutting side and the blade-side cutting side.

Abstract: A needle bar 4 is supported by a needle bar supporter in a manner freely movable up and down relative to a frame. A crank 2 is fixed to an upper shaft 1, rotates with the upper shaft 1, and an output end thereof moves circularly. A crank rod 3 is connected to the crank 2 in a freely rotatable manner. A connection rod 8 is connected to an intermediate portion of the crank rod 3 in a freely rotatable manner, and is connected to the needle bar 4 in a freely rotatable manner. A length of the needle bar 4 and a length from a connecting position of the connection rod 8 and the crank rod 3 to a slider 7 differ. When the crank 2 circularly moves, the connecting position of the connection rod 8 and the crank rod 3 draws a trajectory of an ellipse.

Abstract: In order to prevent a replacement of the needle plate in the situation not suitable for replacing the needle plate, a needle plate detachable mechanism has a needle plate fixing unit for fixing a needle plate on a sewing machine body; a releasing unit for releasing a fixed state of the needle plate; and a fixing-release limiting unit for limiting a release of the fixed state of the needle plate when the needle is positioned below an upper surface of the needle plate or when the sewing machine motor is driven.

Abstract: In order to prevent a replacement of the needle plate in the situation not suitable for replacing the needle plate, a needle plate detachable mechanism has a needle plate fixing unit for fixing a needle plate on a sewing machine body; a releasing unit for releasing a fixed state of the needle plate; and a fixing-release limiting unit for limiting a release of the fixed state of the needle plate when the needle is positioned below an upper surface of the needle plate or when the sewing machine motor is driven.

Abstract: A sewing machine moves a presser foot up and down through a presser-bar lifting lever to depress a cloth. The lever is moved down by a stepping motor at a constant move-down amount. A compression spring is present between the stepping motor and the presser foot. The compression spring is compressed by some of the constant move-down amount of the lever, and applies, to the presser foot, pushing force canceling repulsive force from the depressed cloth. The move-down amount of the presser foot is detected by an encoder, and a thickness of the cloth is calculated by a cloth-thickness calculator. The cloth-thickness calculator performs calculation based on the move-down amounts at two timings in a time period at which the presser foot depresses the cloth and attempts to further move down.

Abstract: A needle bar 4 is supported by a needle bar supporter in a manner freely movable up and down relative to a frame. A crank 2 is fixed to an upper shaft 1, rotates with the upper shaft 1, and an output end thereof moves circularly. A crank rod 3 is connected to the crank 2 in a freely rotatable manner. A connection rod 8 is connected to an intermediate portion of the crank rod 3 in a freely rotatable manner, and is connected to the needle bar 4 in a freely rotatable manner. A length of the needle bar 4 and a length from a connecting position of the connection rod 8 and the crank rod 3 to a slider 7 differ. When the crank 2 circularly moves, the connecting position of the connection rod 8 and the crank rod 3 draws a trajectory of an ellipse.

Abstract: A sewing machine includes a thread take-up lever that supplies an upper thread to a needle from a thread supply source, a hook which catches the upper thread inserted in the needle, and which intertwine the upper thread with a lower thread, and a control unit that controlling a hook release phase at which the hook releases the upper thread in such a way that a hook/upper-thread necessary amount that is necessary when the upper thread is intertwined with the lower thread becomes smaller than a thread-take-up-lever/upper-thread supply amount that is supplied by an operation of the thread take-up lever. The control unit controls the hook release phase at a plurality of timings.

Abstract: A sewing machine moves a needle up and down relative to a cloth based on drive force from a rotating upper shaft to form a stitch. A first output generating unit reciprocates a first output point along an output axis so as to convert the rotational motion of the upper shaft into a linear motion. An assist rod that serves as a connection portion links the first output point with a needle bar. A needle-bar swing unit swings the needle bar. An output shaft moving unit moves a guide that is the output axis in a cloth feeding direction in accordance with the motion of the needle-bar swing unit. The assist rod changes the inclination in accordance with the movement of the output axis, and reciprocates the needle bar in substantially parallel with the output axis while maintaining the inclination.

Abstract: A sewing machine translates a stitchwork frame with which a cloth is fastened along a direction of a plane where the cloth is fastened based on stitchwork data to form a stitchwork pattern. A presser foot located above the cloth has a height changed by an actuator like a stepping motor in accordance with the advancement of a stitchwork formation. Hence, a predetermined clearance between the cloth and the presser foot is maintained.

Abstract: A sewing machine includes a sewing-machine motor that drives, through an upper shaft and a lower shaft, a thread take-up lever, a needle bar, and a shuttle in conjunction one another. In addition, the sewing machine includes a stepping motor different from the sewing-machine motor. A bobbin-thread supply member is driven by drive power from the stepping motor, and applies tension to a bobbin thread in accordance with the drive timing of the stepping motor and the drive amount of the stepping motor. The drive timing of the stepping motor is variable in accordance with a sewing condition.

Abstract: A sewing machine includes an upper shaft rotatable so as to drive a needle bar, a lower shaft rotatable so as to drive a hook, an upper-shaft pulley attached to the upper shaft, a lower-shaft pulley attached to the lower shaft, a belt linking the upper-shaft pulley and the lower-shaft pulley, and synchronizing a rotation of the upper-shaft pulley and a rotation of the lower-shaft pulley with each other, a belt adjusting mechanism contacting the belt and changing a belt length at a tensioned side at which the belt is drawn, and a tensioner tensioning the belt in accordance with the change in the belt length of the belt at the tensioned side.

Abstract: A sewing machine moves a needle up and down relative to a cloth based on drive force from a rotating upper shaft to form a stitch. A first output generating unit reciprocates a first output point along an output axis so as to convert the rotational motion of the upper shaft into a linear motion. An assist rod that serves as a connection portion links the first output point with a needle bar. A needle-bar swing unit swings the needle bar. An output shaft moving unit moves a guide that is the output axis in a cloth feeding direction in accordance with the motion of the needle-bar swing unit. The assist rod changes the inclination in accordance with the movement of the output axis, and reciprocates the needle bar in substantially parallel with the output axis while maintaining the inclination.

Abstract: A sewing machine moves a presser foot up and down through a presser-bar lifting lever to depress a cloth. The lever is moved down by a stepping motor at a constant move-down amount. A compression spring is present between the stepping motor and the presser foot. The compression spring is compressed by some of the constant move-down amount of the lever, and applies, to the presser foot, pushing force canceling repulsive force from the depressed cloth. The move-down amount of the presser foot is detected by an encoder, and a thickness of the cloth is calculated by a cloth-thickness calculator. The cloth-thickness calculator performs calculation based on the move-down amounts at two timings in a time period at which the presser foot depresses the cloth and attempts to further move down.

Abstract: A sewing machine translates a stitchwork frame with which a cloth is fastened along a direction of a plane where the cloth is fastened based on stitchwork data to form a stitchwork pattern. A presser foot located above the cloth has a height changed by an actuator like a stepping motor in accordance with the advancement of a stitchwork formation. Hence, a predetermined clearance between the cloth and the presser foot is maintained.

Abstract: A sewing machine includes a sewing-machine motor that drives, through an upper shaft and a lower shaft, a thread take-up lever, a needle bar, and a shuttle in conjunction one another. In addition, the sewing machine includes a stepping motor different from the sewing-machine motor. A bobbin-thread supply member is driven by drive power from the stepping motor, and applies tension to a bobbin thread in accordance with the drive timing of the stepping motor and the drive amount of the stepping motor. The drive timing of the stepping motor is variable in accordance with a sewing condition.