Latch device used in vehicle door

In a vehicle sliding door having a latch unit provided at a rear edge of the sliding door for maintaining a closed condition of the sliding door, an outside open handle provided on an outer surface of the sliding door, an inside open handle provided on an inner surface of the sliding door, a relay assembly provided within the sliding door for connecting the outside and inside open handle to the latch unit, an inside lock button provided on the inner surface of the sliding door, and a child-proof button provided on the sliding door, said relay assembly comprising:

• a base plate fixed to the sliding door;
• an outer opening lever rotatably mounted on the base plate and coupled to the outside open handle and the latch unit to release the latch unit when the outside open handle is operated;
• a locking lever rotatably mounted on the base plate and coupled to the inside lock button, said locking lever having an unlocked position in which the locking lever interconnects the outer opening lever and the latch unit and a locked position in which the locking lever disconnects the outer opening lever and the latch unit;
• an inner opening lever rotatably mounted on the base plate and coupled to the inside open handle and the outer opening lever to rotate the outer opening lever when the inside open handle is operated;
• a child-proof lever rotatably mounted on the base plate and coupled to the child-proof button, said child-proof lever having a non-child-proof position in which the child-proof lever interconnects the inner opening lever and the outer opening lever and a child-proof position in which the child-proof lever disconnects the inner opening lever and the outer opening lever;
• wherein said locking lever and said child-proof lever are pivotally mounted on the base plate by a first shaft.