Needle plate detachable mechanism and sewing machine having needle plate detachable mechanism

A needle plate detachable mechanism of a sewing machine which forms a seam by vertically driving a needle by a driving force of a sewing machine motor, the needle plate detachable mechanism comprising:

• a needle plate fixing unit capable of being switched between a fixed state where a needle plate is fixed to a sewing machine body and an unfixed state where the fixed state is released;
• a switching mechanism which is connected with the needle plate fixing unit for switching the needle plate fixing unit between the fixed state and the unfixed state;
• a detector for detecting a vertical position of the needle;
• and
• a controller which is electrically connected with the sewing machine motor, the detector and the switching mechanism to determine to allow and prohibit an operation of the switching mechanism, wherein
• the controller prohibits the operation of the switching mechanism when a needle tip of the needle is positioned below an upper surface of the needle plate based on the vertical position of the needle detected by the detector, and
• the controller prohibits the operation of the switching mechanism when the sewing machine motor is driven.