US Patent 7815186 Cartridge

A cartridge includes a base, a tray and a latching element. The base has a boss. The tray is slidably mounted on the base. The base has a cartridge spring corresponding to the tray. The cartridge spring provides the tray a resilient force. The latching element has an eccentric hole that receives the boss of the base. A spring connects the latching element to the base so that the latching element can secure the tray to the base or release the tray from the base. It enhances the retaining of the tray so that even when the cartridge is impacted by an external force, the tray can still be kept closed. The cartridge of the invention provides advantages such as being highly stable, having fewer components, is easy to assemble, and costs less than prior art models.