Escalators (moving stairs) are widely used in public places.
Many a times only a single person is present on the escalator and the entire thing has to move i.e. many vacant stairs. Even vacant stairs have weight, owing to the fact that they are made of steel. So this design tries to obviate the motion of such vacant stairs; which in turn reduces the weight being moved; which therefore results in reduced energy consumption.
The design is such that a continuous steel belt is in motion. It has intermittent notches wherein detachable stair plates (i.e. stairs) fit in as shown in the diagram. As soon as a person nears the escalator to board it, a stair gets fixed into the notch and creates a stair which can be boarded. The same sensor shall sense the presence of a person which in the present day escalators detects our presence as soon as we reach a stationary escalator; and sets it into motion.
The stair steps can be detached once they have moved back to their initial position i.e. after one full loop of circular motion.
There might be safety issues in this design. Big gaps might be created and people may fall down. One way to address this problem is to fit in 3 stairs as soon as a person tries to board an escalator. This again shall result in higher energy consumption but may increase the safety.