Sony’s secret weapon: the 3 layer CMOS sensor

Sony’s secret weapon: the 3 layer CMOS sensor

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Though Sony is perceived to be losing grounds in the smartphone industry, to some extent, it is not. It is true that Sony’s phones are not as popular as they were in couple of years ago. Yet, the Japanese colossus has been dramatically influencing the tech. world in other ways. Being the leader of CMOS sensor industry, by leveraging its cutting edge technologies, sensors made by Sony have great traction towards mainstream high end smartphone players, like Apple and Samsung. In order to maintain its dominance in the field, recently, Sony introduced the world’s first CMOS sensor with 3 layers.

First of all, it is crucial to understand the basic working principal of a CMOS image sensor. CMOS sensors are used in camera to convert and process signals. Like what its name suggests, a sensor will react to and collect light signals, which are analog in form, into electric signals, which are digital in form. For a CMOS sensor used on phones, it has a photodetector, a special kind of diode that converts light into current. Moreover, each pixel is connected with a transistor, aiming to amplify the signals. The good side of using transistors is that the power consumption of CMOS sensor is much reduced, when compared with those using CCD technology, another mainstream solution of image sensors. Of course, adoption of transistors is not entirely perfect, like photons are lost prior to the conversion process. These technical problems are solved using other measures, for instance, using CMOS sensor with back illumination.

So, what makes the 3 layer design special? Traditionally, there are only 2 layers, the part with array of pixels and the part where integrated circuit is located. Sony suggested that a DRAM layer can be added between the two layers, creating a sandwich-like design. DRAM is a kind of random access memory that allows data to be temporarily stored and read at high speed, thus improving efficiency. It is said that through adding DRAM in between, data can be sent from the pixel part to the IC, the region that processing work takes place, at optimal speed.

Therefore, in perspective of a normal consumer, how can our experience of using cameras be improved? Well, as we are in a world which deems taking selfies more and more important to us, it is not uncommon that we will take lots of photos and attempt to pick the best one. With the improved image capturing speed due to addition of DRAM layer, taking selfie will be much more fluent. Moreover, as capturing speed is increased, more frames are recorded per unit time, hence allowing us to create slow motion effect at better quality. To make a conclusion, the invention of the groundbreaking 3 layer CMOS sensor is another good example of how our life is changed by disruptive technologies, proving that these state-of-the-art engineering ideas are actually making our daily life better, from one little step to another.