Before purchasing a CCTV Security Camera, it is the image sensor which we look for in the first place. Image Sensors are something which one should try to understand and find out first in a Security Camera, even before the parameters like TV Lines, or IR, or Focal Length. As evident from the title of this post also, we shall be talking about the two types of Image Sensors majorly available n the market, and the ongoing war between them. These two types of sensors are CCD and CMOS Sensors. CCD stands for Charged Coupled Devices, and CMOS stands for Complementary Metal Oxide Semiconductor.
What are Image Sensors: –
To understand the war between CCD Vs CMOS, we must first understand
the definition of image sensors, and its working in the Security Camera. Image Sensors are located just after the lens of a Camera. When we try to take the image of a place or an object, it happens that the light passes through the lens and falls on the image sensor. The picture elements on the sensor, then collects the light and convert it into voltage electrons. These picture elements are nothing but are popularly known as pixels. These pixels converts the amount of light falling on sensor into analogue voltages, which is further converted into digital signal through a separate Analogue to Digital Convertor.
In CCD sensors, after the processing of light from the pixels, an analogue signal is sent out to be amplified and converted into digital signal through various circuitries like amplifiers, analogue to digital convertors etc. Now although the image quality in CCD sensors is good because of less noise and better sensitivity, but the only disadvantage is its heavy circuitry which is required outside the sensors for conversion and amplification and need heavy power consumption. The increase power consumptions may sometimes result in issues like excessive heat generation within the camera.
CMOS sensors are the recent development in the market. Earlier it was used for imaging purposes only and hence need for more light sensitivity was not felt in that kind of application. Due to which in CCTV application there were issues related to image quality when compared to CCD Sensors. However with the advancement in technology the CMOS sensors were also developed for CCTV type of application, with the increased image quality.
The benefit of CMOS over CCD is the fact that it incorporates amplifiers and convertors within the chip itself leading to reduced cost of production and cheaper cameras in the market. There is no need of a separate electronic circuitry outside the image sensor.
Verdict for “CCD VS CMOS”:-
As we have seen the entire signal processing functions in a CCD image sensor happen outside the chip, whereas same is incorporated on the chip itself in CMOS image sensors. CMOS sensors therefore consumes less power as compared to CCDS sensors, whereas there may be some quality related issues in a CMOS sensor due to less sensitivity and structured noise in the chip.
But as and technology is advancing there are steps taken by the Security Camera Companies to deal with the issues in CCD and as well as CMOS sensors. On one hand efforts are taken to reduce power consumption in a CCD sensor, on the other hand, CMOS technology is also being developed for a CCTV application reducing noise and increasing image quality.
Hence it will not be wrong to say that the gap between the two technologies is converging day by day, be it related to their benefits, or limitations. Therefore it may be irrelevant at times which image sensor you are using if the camera you have chosen is fulfilling all your requirements and serving the purpose of your application.