A coupling assembly, comprising: two screw rods arranged in parallel; a holder mounted on the two screw rods; two shaft sleeve sets; and two connection rod sets, each of which is coupled to a corresponding one of the two shaft sleeve sets, characterized in that each of the two shaft sleeve sets comprises: a first shaft sleeve embedded in the holder, the holder restricting movement of the first shaft sleeve in an extension direction of the screw rod, and at least part of the screw rod being arranged in the first shaft sleeve, and a second shaft sleeve fitted over the screw rod at an outer side and movable on the screw rod; and each of the two connection rod sets comprises: a first connection rod having a first end fixedly coupled to the first shaft sleeve, and a second connection rod having a first end fixedly coupled to the second shaft sleeve, the second connection rod and the first connection rod crossing with each other and being coupled at a junction; wherein there is a first distance between the first shaft sleeve and the second shaft sleeve, and the first connection rod and the second connection rod cross to form a first angle; there is a second distance between the first shaft sleeve and the second shaft sleeve, and the first connection rod and the second connection rod cross to form a second angle; the second angle is different from the first angle. two screw rods arranged in parallel; a holder mounted on the two screw rods; two shaft sleeve sets; and two connection rod sets, each of which is coupled to a corresponding one of the two shaft sleeve sets, characterized in that each of the two shaft sleeve sets comprises: a first shaft sleeve embedded in the holder, the holder restricting movement of the first shaft sleeve in an extension direction of the screw rod, and at least part of the screw rod being arranged in the first shaft sleeve, and a second shaft sleeve fitted over the screw rod at an outer side and movable on the screw rod; and a first shaft sleeve embedded in the holder, the holder restricting movement of the first shaft sleeve in an extension direction of the screw rod, and at least part of the screw rod being arranged in the first shaft sleeve, and a second shaft sleeve fitted over the screw rod at an outer side and movable on the screw rod; and each of the two connection rod sets comprises: a first connection rod having a first end fixedly coupled to the first shaft sleeve, and a second connection rod having a first end fixedly coupled to the second shaft sleeve, the second connection rod and the first connection rod crossing with each other and being coupled at a junction; a first connection rod having a first end fixedly coupled to the first shaft sleeve, and a second connection rod having a first end fixedly coupled to the second shaft sleeve, the second connection rod and the first connection rod crossing with each other and being coupled at a junction; wherein there is a first distance between the first shaft sleeve and the second shaft sleeve, and the first connection rod and the second connection rod cross to form a first angle; there is a second distance between the first shaft sleeve and the second shaft sleeve, and the first connection rod and the second connection rod cross to form a second angle; the second angle is different from the first angle.