Why A Retractable Pen?
Click! Click! Retractable pens feature a very clever mechanism called a "push-push" mechanism. This type of mechanism exists in many forms: old push light switches, cabinet latches, sim card readers, and more. But this is probably the most recognizable implementation.
The main question: why does the pen tip press out when you push the pen down, but the pen tip retracts when you push down again? Let's get into it.
What is A Push-Push Mechanism?
A Push-Push Mechanism allows the user to toggle between two states (on/off, open/closed) with the push of one input. In this case, the press of the pen moves the pen tip out then back in.
What's Inside the Pen?
Let's take the pen apart the top and bottom to see what's inside. First, let's see what's at the top.
