Day-and-night curtain dual-rail dual-control correlation type stopper

A day-and-night curtain dual-rail dual-control correlation type stopper, comprising a limiting seat, a down-running stop block, an up-running stop block, a main screw rod, a main gear, an auxiliary screw rod and an auxiliary gear, a side wall of the limiting seat being provided with a main threaded through-hole and an auxiliary threaded through-hole, one end of the main screw rod being inserted in the main threaded through-hole and being in threaded connection with the main threaded through-hole, the main gear being fixedly mounted on the main screw rod, the main screw rod being innerly provided with a main through-hole, the main through-hole being inserted on a main mandrel for driving a lifting winder of a curtain bottom rail and the main screw rod being able to slide along the main mandrel, the main gear meshing with the auxiliary gear, the auxiliary gear being provided with a threaded through-hole, the auxiliary gear being inserted on the auxiliary screw rod via a threaded through-hole and being in a threaded connection with the auxiliary screw rod, one end of the auxiliary screw rod being inserted in the auxiliary threaded through-hole and being in a threaded connection with the auxiliary threaded through-hole, the auxiliary screw rod being innerly provided with an auxiliary through-hole, the auxiliary through-hole being inserted on an auxiliary mandrel for driving a lifting winder of a curtain top rail and the auxiliary screw rod being able to slide along the auxiliary mandrel, a down-running stop boss being provided on the main screw rod, when the main mandrel drives the curtain bottom rail to move downwards, the main screw rod being driven to rotate simultaneously, the limiting seat being fixed and enabling the main screw rod threadedly connected thereto to slide along the main mandrel, the main screw rod driving the main gear to rotate and move simultaneously, the main gear driving the auxiliary gear to rotate, the auxiliary gear moving synchronously with the main gear along the auxiliary screw rod, the down-running stop boss moving along with the main screw rod, and when the curtain bottom rail moves downwards to a lowest position, the down-running stop block blocking the down-running stop boss so as to prevent the main screw rod and the main mandrel from continuing to rotate, a second end of the auxiliary screw rod being provided with an up-running stop boss and a synchronous linkage boss, an end face of the auxiliary gear being provided with a synchronous linkage shifting block, when the main mandrel drives the curtain bottom rail to move upwards, the main screw rod being driven to rotate in a reverse direction simultaneously, the limiting seat enabling the main screw rod threadedly connected thereto to slide in a reverse direction along the main mandrel, the main screw rod driving the main gear to rotate in a reverse direction and move in a reverse direction simultaneously, the main gear driving the auxiliary gear to rotate in a reverse direction, the auxiliary gear moving with the main gear in a reverse direction synchronously along the auxiliary screw rod, when a lifting rope of the lifting winder of the curtain top rail loses a weight of the curtain top rail, the synchronous linkage shifting block contacting the synchronous linkage boss and shifting the synchronous linkage boss so as to drive the auxiliary screw rod to follow the auxiliary gear in synchronous rotation, the auxiliary screw rod driving the auxiliary mandrel so that the auxiliary mandrel follows the main mandrel in synchronous rotation, the limiting seat enabling the auxiliary screw rod threadedly connected thereto to slide along the auxiliary mandrel, the up-running stop boss moving along with the auxiliary screw rod, and when the curtain top rail running up to a topmost position, the up-running stop block blocking the up-running stop boss so as to prevent the auxiliary mandrel and the main mandrel from continuing to rotate.