Sewing machine

A sewing machine comprising:

• a thread take-up lever that is formed in a swayable manner and that includes a swaying axis provided in a right-left direction and a needle thread hooking section which hooks a needle thread provided closer to a front side than the swaying axis;
• a sewing needle that is supported by a vertically-movable needle bar and into which the needle thread is to be inserted;
• a shuttle that makes stitches by hooking the needle thread inserted into the sewing needle;
• an upstream grip section having an upstream grip section main body which grips the needle thread in a pinching manner and an upstream drive section which switches the upstream grip section main body between a closed state where the needle thread is gripped and an open state where the gripped needle thread is released;
• a downstream grip section
• that is disposed at a downstream position on a needle thread path with respect to the upstream grip section and an upstream position with respect to the thread take-up lever, and
• that has a downstream grip section main body which grips the needle thread in a pinching manner and a downstream drive section which switches the downstream grip section main body between the closed state where the needle thread is gripped and the open state where the needle thread is released from the gripped state;
• a circular movement section
• that bends the needle thread via a first needle thread portion of the needle thread located between the upstream grip section main body and the downstream grip section main body by circularly moving the first needle thread portion, and
• that has a circular movement arm which contacts the needle thread and whose circular movement axis is oriented in a right-left direction, and a needle thread motor which circularly moves the circular movement arm in a first direction in which a degree of bend of the needle thread becomes greater and a second direction opposite to the first direction and which circularly moves the circular movement arm in a range of circular movement between a first end position corresponding to an end in the first direction and a second end position corresponding to an end in the second direction;
• a needle thread support member that supports, in a right-left direction, a range on both sides of the first needle thread portion of the needle thread including the first needle thread;
• a presser foot that
• moves between a cloth surface contact position where the presser foot contacts the cloth surface and a cloth surface apart position where the presser foot is apart from the cloth surface;
• that has a presser foot main body and a needle thread fixing section which fixes a second needle thread portion of the needle thread situated between a cloth and the thread take-up lever, at a position apart from upper surface of the cloth and at a position deviating toward the upper surface of the cloth surface from an insertion position where the sewing needle is to be inserted, wherein
• the presser foot main body has a cloth surface contact section that contacts the cloth surface when the presser foot is at the cloth surface contact position and a main body structure section formed closer to a rear side than the cloth surface contact section, and wherein
• the needle thread fixing section has
• a rod-shaped thread hooking rod,
• a thread hooking rod support that supports the thread hooking rod and reciprocally moves in a front-back direction by means of a crank mechanism with respect to the main body structure section while swaying in a right-left direction, and
• a needle thread receiving section
• which fixes the needle thread together with the thread hooking rod and
• which has an elastic section provided at a position on the cloth surface contact section deviating toward the upper surface of the cloth with respect to the insertion position where the sewing needle is to be inserted, and a needle thread receiving section main body which is attached to the elastic section and which fixedly pinches the needle thread together with the thread hooking rod, wherein the thread hooking rod swivels when the thread hooking rod support reciprocally moves in the front-back direction while swaying in the right-left direction,
• that moves between a cloth surface contact position where the presser foot contacts the cloth surface and a cloth surface apart position where the presser foot is apart from the cloth surface;
• a needle thread fixing drive section that actuates the crank section and performs switching between a fixed state where the needle thread fixing section fixes the needle thread and a released state where the needle thread fixed by the needle thread fixing section is released;
• a storage section that stores embroidery data including data pertaining to a stitch length and a remaining length of the needle thread for each stitch;
• and
• a control section
• that controls operation of the upstream drive section, operation of the downstream drive section, operation of the needle thread motor, and operation of the needle thread fixing drive section;
• that, in a first segment that is at least a portion of a segment from a top dead center of the shuttle to a bottom dead center of the shuttle, circularly moves the circular movement arm, by control of the needle thread motor, in the second direction through an angle corresponding to a stitch reference length which is a needle thread length of a stitch achieved while an n+1th stitch next to a proximal nth stitch (“n” is an integer), among stitches already made in the cloth, is fixed to the needle thread fixing section;
• that, in a second segment that is at least a portion of a segment from the bottom dead center of the thread take-up lever to the top dead center of the thread take-up lever, circularly moves the circular movement arm, by control of the needle thread motor, in the first direction through an angle corresponding to a length which is obtained by subtracting a needle thread remaining length, which is a length of the needle thread projecting out of the cloth surface in the nth stitch, from the stitch reference length achieved at the nth stitch;
• that, in a third segment that is at least a portion of the segment from an end position of the second segment to a position where the shuttle hooks the needle thread, circularly moves the circular movement arm, by control of the needle thread motor, up to the first end position in the first direction;
• that, on occasion of control of the needle thread motor, generates from the embroidery data, on a per-stitch basis, angle correspondence data that specify an angle of the needle thread motor representing a rotational position of the needle thread motor, for each angle of a main shaft motor representing a rotational position of the main shaft motor which rotates the main shaft for transmitting torque to the thread take-up lever, and also controls, on the basis of the angle correspondence data, a position of the needle thread motor to an angle of the needle thread motor corresponding to the angle of the main shaft motor, as the angle of the main shaft motor changes as a result of rotation of the main shaft motor;
• that controls the upstream drive section, thereby bringing the upstream grip section into a closed state at any position in a segment from an end position of the third segment section to a position where the shuttle hooks the needle thread, and brings the upstream grip section into an open state at any position in a segment from the end position of the second segment to a start position of the third segment;
• that controls the downstream drive section, thereby bringing the downstream grip section into a closed state at any position in a segment from the end position of the second segment section to a position where the upstream grip section is switched from the closed state to the open state, and brings the downstream grip section into an open state at any position in a segment from a position where the upstream grip section is switched from the open state to the closed state to a position where the shuttle hooks the needle thread;
• and
• that controls the needle thread fixing drive section, whereby the needle thread fixing drive section stops driving, and the thread hooking rod fixedly pinches the needle thread together with the needle thread receiving section, in at least a segment from when the sewing needle is inserted into the cloth to when the shuttle hooks the needle thread.