Multiple metal connecting blocks are installed on the side of the smart door that contacts the steel door leaf. Multiple concave grooves are evenly installed on the side of the steel door leaf that contacts the main door body. These concave grooves correspond to the metal connecting blocks. The metal connecting blocks have two perpendicularly intersecting recessed holes (No. 1 and No. 2) in the horizontal direction. The No. 1 recessed hole is perpendicular to the bottom of the concave groove. A protrusion rolls within the No. 1 recessed hole, and two separate locking blocks roll within the No. 2 recessed hole. The opposing surfaces of the two locking blocks are beveled. The contact surface between the protrusion and the locking block is also beveled, and the protrusion and locking block roll in the middle.
When the protrusion extends into the No. 1 recessed hole, it pushes the two locking blocks to roll outwards into the No. 2 recessed hole. The concave grooves also contain locking slots to accommodate the locking blocks. A metal frame is installed on the inner wall of the concave groove, and a switch is also included. The switch is connected to the metal frame via a wire. A light bulb is connected to the metal connecting block via a wire, and the light bulb is installed on the outside of the main door body. The main door is made of iron. Magnets are attached to the outside of the main door. A thin iron sheet is sandwiched between the steel door leaf and the main door. The length and width of the main door are greater than the length and width of the steel door leaf.
