How will CCD work now in India

How a CCD sensor works

It was in September 1969 when the two physicists from Bell Labs met for a brainstorming session. The question was: How could a new type of memory chip be constructed with the help of the photoelectric effect - a memory for digital technology, which was still young at the time? Boyle and Smith didn't even have in mind at the time that you might be able to take pictures with the technology.

They used silicon, the standard material in digital technology, as the raw material for their sensor. Because silicon also has the photoelectric effect: if light falls on it, electrons that were previously firmly bound in the silicon become electrons that flow freely in the silicon. And: the more light falls on the silicon, the more electrons start to flow. Photo cell, that's what experts call this structure - a principle that is also behind every solar cell.

Boyle and Smith came up with two crucial tricks. On the one hand, they combined many photocells into a kind of checkerboard pattern. Chips were created from 10 by 10 fields, for example, that is 100 fields or, in modern German, pixels. On the other hand, they came up with a method of how these pixels can be read out. Basically, this is done by applying a small electrical voltage. In this way, the electrons that were created when the image was taken are finally released from their silicon prison. Boyle and Smith came up with the idea of ​​reading out the pixels on their chip line by line - a highly effective method that turned out to be. Charge Coupled Device, this is what the two US physicists called their invention, CCD for short.

Just a week after the brainstorming session, a first primitive prototype was ready. Boyle and Smith quickly realized that the patent is not so good at storing data, but that it is all the better for recording images. And so they built their CCD chip into a video camera for the first time in 1970, just one year after the crucial brainstorming session.