Patent ID: 8819993

Claim:
A rail module of a covering of a building's opening, comprising: a fixed first rail having a locking slot; a second rail being turned between a first position and a second position, wherein the second rail is connected to the first rail when the second rail is turned to the first position, and the second rail is separated from the first rail when the second rail is turned to the second position; and a first restricting member, which is movably provided on the second rail, having a contacting portion and a protrusion at opposite sides thereof, wherein the protrusion engages the locking slot of the first rail when the second rail is turned to the first position; a pulley assembly being able to move in the first rail and the second rail when the second rail is turned to the first position, wherein the pulley assembly has a driving portion in association with the contacting portion of the first restricting member; wherein the driving portion of the pulley assembly touches the contacting portion of the first restricting member to move the first restricting member and disengage the protrusion of the first restricting member with the locking slot of the first rail when the pulley assembly is moved into the second rail, so that the second rail is able to be turned to the second position; and a second restricting member having a stop block, wherein the pulley assembly has a stop portion in association with the stop block, and the stop portion touches the stop block to prevent the pulley assembly moving out of the second rail when the second rail turns to the second position from the first position and the pulley assembly is moved toward the second restricting member; wherein the second restricting member is moved to a predetermined position to block both the first restricting member and the pulley assembly when the second rail leaves the first position, so that the first restricting member and the pulley assembly are restricted in the second rail, and the second restricting member is moved away from the predetermined position when the second rail is turned back to the first position, whereby the protrusion of the first restricting member is engaged with the locking slot of the first rail, and the pulley assembly is able to be moved into the first rail.