A balance system used with a door of a cupboard comprises a transmission shaft, a first pulley on the transmission shaft, and a balance component. The first pulley is connected to a door belt, one end of the door belt is secured to the first pulley, and the other end of the belt is connected to the door. The balance component comprises a balancing member, a balancing belt and a second pulley on the transmission shaft. One end of the balancing belt is connected to the second pulley, and the other end of the balancing belt is connected to the balancing member, such that the balancing member is hung on the second pulley. The first pulley and the second pulley rotate synchronously, and the door belt and the balancing belt are wound oppositely. With the balance system, a small driving force can open/close the door.

A track of a vertically stacking door includes a vertical track, a first curved track portion, a second curved track portion, a first horizontal track portion coupled to the first curved track portion, and a second horizontal track portion coupled to the second curved track portion. The first curved track portion and the second curved track portion are split off from the vertical track and the first curved track portion and the second curved track portion each comprises multiple radii of curvature.

A track of a vertically stacking door includes a vertical track, a first curved track portion, a second curved track portion, a first horizontal track portion coupled to the first curved track portion, and a second horizontal track portion coupled to the second curved track portion. The first curved track portion and the second curved track portion are split off from the vertical track and the first curved track portion and the second curved track portion each comprises multiple radii of curvature.

In example implementations, a vertical stacking door includes an end cap that is coupled to a panel. The end cap includes a body portion, a cam lever to rotate around an axis to generate a lift force to lift and separate an adjacent panel of a plurality of panels of the vertical stacking door, a first track wheel, a second track wheel, and a third track wheel.

A stacking screen door has two rails and multiple door panels. Each one of the rails has a groove, a conductive bar, and an elastic assembly. The conductive bar is movably located in the groove. The elastic assembly is connected to the conductive bar and the groove, and is configured to push the conductive bar out of the groove. The door panels selectively move along the two rails and are sequentially connected vertically to each other in the rail. Each one of the door panels has two electric assemblies and multiple display screens. Each one of the display screens is electrically connected to the two electric assemblies. When each one of the door panels moves along the two rails, each one of electric assemblies is respectively connected to the conductive bar. Therefore, power can be supplied to the display screens.

A stacking screen door has two rails and multiple door panels. Each one of the rails has a groove, a conductive bar, and an elastic assembly. The conductive bar is movably located in the groove. The elastic assembly is connected to the conductive bar and the groove, and is configured to push the conductive bar out of the groove. The door panels selectively move along the two rails and are sequentially connected vertically to each other in the rail. Each one of the door panels has two electric assemblies and multiple display screens. Each one of the display screens is electrically connected to the two electric assemblies. When each one of the door panels moves along the two rails, each one of electric assemblies is respectively connected to the conductive bar. Therefore, power can be supplied to the display screens.