Compliant Constant-Stiffness Hinge Mechanism for Thin Foldables

The patent uses a flexible printed circuit board (FPC) as the elastic component instead of a helical spring. The FPC contains an elastic region with a serpentine pattern that can deform elastically to provide the required elastic force. This flexible film structure achieves the same functional effect as a spring while occupying significantly less space and reducing device weight.

The patent replaces the traditional mechanical helical spring system with an integrated flexible circuit board structure. The elastic region of the FPC is designed with specific geometric patterns (serpentine shape) that provide the necessary elastic properties, thereby substituting a separate mechanical spring component with a multi-functional flexible circuit structure.

The patent merges the elastic component and the circuit board into a single integrated structure. The FPC serves dual functions: it provides the elastic force through its deformable serpentine pattern and simultaneously serves as the electrical connection medium. This integration eliminates the need for separate spring and circuit components, reducing overall device weight while maintaining damping performance.

The flexible printed circuit board performs multiple functions: it provides elastic force through its elastic region, maintains electrical connections between components, and enables the damping mechanism's operation. This multi-functional design replaces what would traditionally require separate components (spring, electrical connectors, etc.), thereby reducing device weight.