Buttonhole switch mechanism

A buttonhole switch mechanism of a buttonhole sewing machine comprising:

• a buttonhole presser mounted on a lower end of a presser bar of the sewing machine and having a presser frame that is movable in a front-and-rear direction with respect to the presser bar, and two projection portions that are provided side by side in the front-and-rear direction at an interval according to the diameter of a button and move integrally with the presser frame;
• a buttonhole switch mechanism disposed on an arm section of the sewing machine and having a detection switch of which contacts are electrically connected when the presser frame is located on the foremost side and when the presser frame is located on the rearmost side;
• a feed dog disposed below the buttonhole presser to move cloth, which is an object to be sewn, in the front-and-rear direction at a predetermined feed pitch in cooperation with the presser frame;
• a sewing needle forming stitches in the cloth with vertical movement and adapted to be movable in a right-and-left direction;
• a controller performing control on the movement of the feed dog and the sewing needle on the basis of the electrical connection of the detection switch of the buttonhole switch mechanism;
• a fixing member fixed to a non-movable part of a sewing machine main body;
• a mount supported so as to be movable in the front-and-rear direction with respect to the fixing member;
• an adjustment mechanism adjusting and fixing the relative positions of the fixing member and the mount in the front-and-rear direction;
• a lever member supported by a rotary shaft provided at the mount so as to be rotatable in the front-and-rear direction and being capable of extending a lower end portion between both the projection portions of the buttonhole presser
• an adjustment dial provided between the fixing member and the mount, which is rotated to adjust a push-in amount between a buttonhole switching lever and the detection switch by moving the mount forward in parallel with respect to the fixing member while scales provided on one of the fixing member and the mount in the front-and-rear direction and an indicator combined with the scales on the other one of the fixing member and the mount are read;
• and
• the detection switch fixed to the mount and electrically connected as the lower end portion of the lever member is pushed and rotated by each projection portion.