A ejector assembly, comprising: an ejector (10) with a shape of “L”, being provided to rotate around an axis; a lock element (20), being provided to move along a direction substantially perpendicular to a plan of the rotation of the ejector (10); wherein the ejector (10) includes a cut-out portion (12), the lock element (12) includes an end portion (21), and the end portion (21) is provided to match with the cut-out portion (12) to prevent the ejector (10) from rotating.