According to the present disclosure, a projector lift is provided to raise and lower a projector from the ceiling. The adhesive additives contain castor oil, a mixture of castor oil and triglycerides, or a reaction product from the transesterification of one or more polyols and one or more triglycerides. The detecting structure has a movable socket and a flexible conductor, wherein the movable socket is slidably sheathed on the pillar, and an interval space is formed between the movable socket and the pillar.