To be simply, CCD stands for Charged Coupled Device, is a type of sensor in most security cameras used to capture an image by taking the light and translating it into digital data. There are thousands of tiny little pixels that make up the surface of the sensor so that every little facet of light will be caught, converted, and refined into electrical energy, and organized into a digital image. It is through the pixels that the light is translated into electrons, which in turn, become the digital data you need in order to print, edit, or store a picture.
CCD's have been in use in digital cameras the longest. Another type of sensor is the CMOS or complementary metal oxide semiconductor. Both use the same basic principal, but have their own unique attributes. A CCD creates high quality, low noise images. CMOS sensors are more susceptible to noise. CMOS sensors use very little power. CCD's generally use as much as 10 times the amount of power a similar CMOS sensor would need.
Let’s see how they work with cameras differently.First,A CCD basically moves the charge to one place on the chip where it can be read, and then each pixel’s value is given a digital value by an analog-to-digital converter (ADC). CMOSs on the other hand, use transistors to move the charge with several transistors at each pixel. In addition, the CMOS uses conventional wiring to facilitate this process. Second, CCDs can be thought of as a photoactive layer over a series of pits. When the photo sensitive layer is struck by light, packets of electrons gather in these pits. CMOSs convert light to electrons in the same manner. The difference between the CCD and the CMOS is how they read and/or transfer the electrons.
CCD’s are manufactured in sizes ranging from less than ¼ inch to over 1 1/3 inches. Usually “the bigger is better” theory applies here. Larger CCDs usually produce higher resolution images and may be more sensitive to light. However, for most security cameras the two most popular sizes of CCDs seem to be the ¼ and 1/3 inch. Again, there are many factors that determine the optimum size for a ccd security camera.
This should give you some good working knowledge of what a CCD is and what it does to make things work inside a security camera. Remember that CCDs are usually higher performers than CMOSs but at a cost. Although CCDs are more expensive than CMOSs, their greater sensitivity to light makes them an excellent candidate for use in security cameras. CCDs actually react to an impressive 70 percent of the light that strikes them. In addition, most manufacture CCDs are inherently sensitive to near-infrared radiation which makes them an excellent candidate for night vision, infrared, or near zero LUX video recording.