Operating an elevator door

A system for operating an elevator car door, upon an elevator car residing at a landing zone of a landing, the system comprising:

• a door coupler comprising one more coupling elements for engaging one or more counter elements of a landing door to couple the landing door to an elevator car door and for disengaging from the one or more counter elements of the landing door to decouple the landing door from the elevator car door;
• a locking mechanism comprising
• a rotatable lock hook assembly and a lock latch, wherein the lock hook assembly comprises a lock hook portion arranged to selectively engage or disengage the lock latch via rotation of the lock hook assembly to set the locking mechanism, respectively, into a locked state or an unlocked state,
• wherein the door coupler is arranged to serve as an actuation assembly for rotating the lock hook assembly;
• a safety circuit for indicating a state of the locking mechanism, wherein the safety circuit comprises a switch that is closed in the locked state of the locking mechanism to cause an electric current to flow in the safety circuit and that is open in the unlocked state of the locking mechanism to prevent the electric current from flowing in the safety circuit;
• and
• a door controller arranged to
• operate a door driving system, in dependence of movement of the elevator door, to selectively relax the door coupler or to exert a force that causes the door coupler to rotate the lock hook assembly to set the locking mechanism into the locked or unlocked state,
• monitor the flow of said electric current in the safety circuit, and
• detect compromised operation of the locking mechanism in response to detecting the flow of said electric current upon relaxation of the door coupler when the elevator door is closed,
• wherein the door coupler is in a relaxed state when the door driving system does not exert a force to the one or more coupling elements and wherein the system comprises an actuation member coupled to the door coupler and arranged to exert a force that causes the door coupler to rotate the lock hook assembly towards the unlocked position of the locking mechanism upon relaxation of the door coupler, where the force exerted by the actuation member is smaller than the force exerted to the one or more coupling elements of the door coupler by the door driving system.