In this case, the electricity deposited in each bucket is transported to the exit in sequence. If the amount of the electricity is measured each time, we can count backward, how much and in which number of bucket electricity is deposited. It means that we can know what extent of intensity of light is exposed to each SPD spread over, although only in order. You would understand a little better with a drawing carried in that book. Imagine that many buckets are hanging on to the crankshaft this way.
Buckets go up and down with the rotation of the shaft.
Let's define the mechanism is that when a bucket goes to top, it tilts to right and empty out the water into the bucket to its right. If the crank-shaft is rotated many times, the water is transported from left to right in succession. Instead of rotating the crank-shaft, if we send a signal called clock pulse, the electricity is sent to the exit in succession. In practice, SPD's are spread over not only in one horizontal line, but in a plane on the substrate, just as the floor with tiles, the bucket brigade of CCD's form many rows vertically, with horizontal CCD being placed at their ends for passing signals on at a right angle to them. Products, brands and companies names are trademarks or registered trademarks of their respective companies.