SPRING BIAS/COUNTERBALANCE CARTRIDGE
Original Publication Date: 1980-Feb-29
Included in the Prior Art Database: 2004-Apr-02
Xerox Disclosure Journal
It is often desirable to hold a pivoting cover, such as a copier platen cover, in an open or up position and to have it biased down or closed in its horizontal position. This concept provides a spring bias counterbalance cartridge for that purpose. The cartridge comprises two end plates 10 each having a shaft 12 with a snap fastener 14 at one side and a cylindrical tube 16 with a snap fastener closure 18 at the opposite side of the end plate. The cartridge is assembled by placing two springs over the respective cylindrical tubes and pushing the two end plates together so that the snap fasteners fasten in position. In this position, the end plates and cylindrical tubes serve only to orient the springs retaining them in position in a natural, relaxed state. As shown in Figure 2, in operation to hold a platen cover in its open position, the spring cartridge is inserted in a holder 22 in platen cover 24 and holder 28 in support arm 30 €or the platen cover. In this position the spring is under compression. When in the closed position, the spring biases the cover down in addition to the shear weight of the platen cover. When fully opened, the compressive force of the spring cartridge supports the cover in an open position. When the platen cover is lowered to about the 45 degree angle, the force of gravity overcomes the compressive force of the spring and the platen cover will fall.