manual cordless spring lifting system

Imagine you have a curtain that can be rolled up and down, but there is no cord or rod to pull it. Cordless roller shades are just like these curtains in that they use a special spring to control the rise and fall of the shades. This special spring is called a variable force spring. The word “variable force” may sound complicated, but it's actually like a spring that changes the amount of force.   The spring is hidden at the top of the roller shade, and when the shade needs to be lowered, the spring is tensioned, just like when you pull back on the bowstring of a bow and arrow. When you let go, the spring uses its stored energy to roll the curtain up quickly and smoothly. Now, if we want the curtains to stop somewhere, like in mid-air, the variable force spring can do that for us too. It's like an intelligent assistant that senses where the curtains need to stop and then adjusts its force so that the curtains stay right there and don't continue to roll up or fall down. Also, these roller shades are designed to be safe, with no ropes or chains, so you don't have to worry about kids or pets getting tangled in the ropes.   To summarize, the spring mechanism of a cordless roller shade is a built-in smart spring that automatically controls the raising and lowering of the curtains, as well as allowing the curtains to stop in any position when needed, which is both convenient and safe.