Everyone today uses cameras, as most are integrated in your smartphone, and it’s rather unusual to have a cell phone without a camera these days. We take pictures, upload them to various social networks and are happy about the fact that the moment you see something you want to share, you take a picture, and the next moment it’s already on your online album. Ever wondered how these interesting and funny moments get converted to pixels? It’s all done by an image sensor. Without an image sensor you wouldn’t be able to do that, so let’s get back to basics first – what is an image sensor?
An image sensor is a device that can convert optical images, the things you see around you, into electronic signals to create a digital photo. An image sensor is used in all kinds of cameras, whether professional ones, or the ones you have at home, integrated into your phone or camcorders. The image sensor makes this possible, so let’s explain how it works.
How does it work?
The image sensor works differently depending on what kind of sensor it is. Today, there are two types of sensors – the charge-coupled device, or CCD for short, and the complementary metal-oxide-semiconductor, or CMOS active pixel sensor. When using a CCD image sensor, the light that comes to the chip is held in the photo sensor as an electrical charge, and they are then converted to voltage, which is then converted into digital information. The name of this sensor comes from the way it reads the charges on its pixels. After the chip is holding the charges, those in the first row get transferred into a sensor called the read out register, and then they go to an amplifier and after that to a converter which makes them digital. After this row is read, its charges are deleted from the register and the new row comes in. Each row is “coupled” to the row above it and that way they are read one at a time. The CMOS image sensor has transistors at each pixel, and those transistors amplify and move the charge using traditional wires. The advantage of this sensor is that it can read each pixel individually.
Which image sensor is better?
This depends what you are looking for, because both the CCD image sensor and the CMOS image sensor have their advantages and disadvantages. For once, the CCD sensor is better at high quality images, while the CMOS one usually has more noise. However, CMOS is cheaper because it’s easier to make, and uses less power. So if you don’t really need very high quality images and don’t plan to give too much money, the CMOS image sensor might be the right choice for you. CMOS sensors are improving every day, and soon they will be able to make images as high quality as the CCD sensors. Keep an eye on the image sensor industry because we hope that we will have more interesting news in this area very soon!