Rotating shaft apparatus, support system, and foldable-screen device

A foldable-screen device, comprising:

• a foldable screen and a rotating shaft apparatus, wherein the rotating shaft apparatus comprises:
• a first primary support member, having a first support surface, wherein the first support surface is configured to support a part of the foldable screen;
• a second primary support member, having a second support surface, wherein the second support surface is configured to support a part of the foldable screen, and the second primary support member is configured to rotate relative to the first primary support member;
• a first secondary support member, comprising a first connection part and a first cantilever part that are fixedly connected, wherein the first connection part is located on a side facing the second support surface and is connected to the second primary support member, the first cantilever part comprises a first cantilever segment, the first cantilever segment is located on a side facing the first support surface;
• and a lubrication structure, at least disposed between at least a part of the first cantilever segment and the first primary support member.