Patent attributes
A cushion unit includes a frame having a plurality of corners, and a plurality of reinforcing corner plates respectively disposed in the corners. Each reinforcing corner plate has two main portions angled to each other to form a substantially L-shape, and two wing portions projecting respectively from the main portions. Each corner has two adjacent corner wall sections respectively formed with first engaging grooves for engagement with the wing portions of the respective reinforcing corner plate. The main portions of the reinforcing corner plates are disposed respectively on inner sides of the corner wall sections of the corners when the wing portions of the reinforcing corner plates engage respectively the first engaging grooves in the corner wall sections.
