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.

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.

A thread positioner provided on a needle plate of a double chain stitch sewing machine for forming a seam by a plurality of needle threads and a looper thread, wherein the thread positioner includes a needle thread holding plate provided below the needle plate 30, the needle thread holding plate extending horizontally from a front to a rear, a rear end portion of the needle thread holding plate includes: a guide portion for guiding the plurality of needle threads; and a thread positioning portion for regulating a movement of the plurality of needle threads in a right-and-left direction, and the thread positioning portion includes: a protrusion linearly protruded rearward from the guide portion; flat portions formed on left and right side surfaces of the protrusion; and an inclined portion formed on a tip of the protrusion, the inclined portion being inclined from a right to a rear left.

A feed dog device of a sewing machine includes a driving unit, a needle plate unit, a feed dog unit, an up-down transmitting unit, a horizontal transmitting unit and a direction adjusting unit. The direction adjusting unit includes a stepper motor with a variable rotational speed controlled in accordance with a speed of the driving shaft of the driving unit, and a linkage mechanism actuatable by the stepper motor to be moved to different positions so as to interfere with a horizontal reciprocating motion by the horizontal transmitting unit such that the horizontal reciprocating motion cooperates with the up-down reciprocating motion by the up-down transmitting unit to bring the feed dog unit into performing a variable moving course.

A feed dog device of a sewing machine includes a driving unit, a needle plate unit, a feed dog unit, an up-down transmitting unit, a horizontal transmitting unit and a direction adjusting unit. The direction adjusting unit includes a stepper motor with a variable rotational speed controlled in accordance with a speed of the driving shaft of the driving unit, and a linkage mechanism actuatable by the stepper motor to be moved to different positions so as to interfere with a horizontal reciprocating motion by the horizontal transmitting unit such that the horizontal reciprocating motion cooperates with the up-down reciprocating motion by the up-down transmitting unit to bring the feed dog unit into performing a variable moving course.

A sewing machine includes a needle plate, a bed portion, a first urging member, a first engagement member, a second engagement member, and a lock release mechanism. The bed portion is configured to support the needle plate. The first urging member is provided inside the bed portion and configured to urge the needle plate upward. The first engagement member is provided on the needle plate. The second engagement member is provided inside the bed portion, and is configured to fix the needle plate in a fixed position by being engaged with the first engagement member of the needle plate pressed downward against an urging force of the first urging member. The lock release mechanism is configured to release the engagement of the first engagement member and the second engagement member.

A sewing machine includes a needle plate, a bed portion, a first urging member, a first engagement member, a second engagement member, and a lock release mechanism. The bed portion is configured to support the needle plate. The first urging member is provided inside the bed portion and configured to urge the needle plate upward. The first engagement member is provided on the needle plate. The second engagement member is provided inside the bed portion, and is configured to fix the needle plate in a fixed position by being engaged with the first engagement member of the needle plate pressed downward against an urging force of the first urging member. The lock release mechanism is configured to release the engagement of the first engagement member and the second engagement member.

A method and the device for acquiring and processing measurement quantities in a sewing machine (1) using at least one camera (25), situated on a sewing machine (1), for the acquisition and processing of image data for sewing machine elements and sewing elements. An image processing unit connected downstream from the camera (25) processes the images supplied by the camera (25), taking into account data stored in a target quantity memory, and influences the behavior of the machine control unit dependent on the result of the processing.

A needle plate replacement device including positioning mechanisms provided in an opposing manner in the needle plate and the bed portion, the positioning mechanisms positioning the needle plate to an attaching position in the bed portion; a lock mechanism including a locking member provided in the bed portion and a locked member provided in the needle plate, in which by mounting the needle plate on the attaching position in the bed portion, the locking member and the locked member is locked to each other thus maintaining a locked state; a push-up mechanism provided in the bed portion, the push-up mechanism pushing up the needle plate mounted on the bed portion towards a dismount position above the bed portion; and a release mechanism cancelling the locked state between the locking member and the locked member of the lock mechanism by being interlocked with an operation of the push-up mechanism.

A needle plate replacement device including positioning mechanisms provided in an opposing manner in the needle plate and the bed portion, the positioning mechanisms positioning the needle plate to an attaching position in the bed portion; a lock mechanism including a locking member provided in the bed portion and a locked member provided in the needle plate, in which by mounting the needle plate on the attaching position in the bed portion, the locking member and the locked member is locked to each other thus maintaining a locked state; a push-up mechanism provided in the bed portion, the push-up mechanism pushing up the needle plate mounted on the bed portion towards a dismount position above the bed portion; and a release mechanism cancelling the locked state between the locking member and the locked member of the lock mechanism by being interlocked with an operation of the push-up mechanism.