A shift register is a kind of signal transfer device integrating
storage elements (memory devices). When an object is detected
inline for sorting, ejecting, processing, etc.,
it is often impractical to use the signals for immediate control.
In a coating line, for example, coating at the moment of detection
may have an adverse effect such as splashing the paint on the sensor,
which requires some distance between the position of detection and control.
Shift registers are convenient for use in these situations.
The data signals generated at the moment of detection are stored and
sent to the point of control in the order they are required.