Source:Intuitive Mechanical Learning,Fanyu Animation
SD cards are familiar to everyone; we have all seen and used them. When inserted, they automatically lock in place, and with a press, they pop out again. But what structural principle enables this function?
The mechanism is a classic application of springs and a “maze groove,” designed ingeniously:
The clever part lies in the design of the guide groove, where each corner has a step so that the pull rod can only move along a specific trajectory and cannot reverse. This structure is quite similar to that of a ballpoint pen:
As can be seen, the design does not aim for a complex structure but rather for ingenuity.