Tuesday, March 25, 2014

HD IP Surveillance Camera Image Sensor most critical




HD IP cameras has excceeded traditional analog cameras from common sense. Now HD megapixel ipcamera,2.0 megapixel ip camera ,3.0 migapixel ip camera have formed Diversified product structure.  A  HD IP Camera can be seen as a combination of a HD camera and a computer.It Progressive scans though CMOS/CCD, capture images through a single SoC chip processing, direct transmission over  IP network ,so user can view real time HD video , data storage and managemen in local or remote area .Add this is based on  ip website structure.

There are two kinds IP cameras if Classified by image sesor. About CMOS Sensor ,there are conventional CMOS and Exmor CMOS (Back-illuminated CMOS).The structure and operating principle of CCD and CMOS are as follows:

CCD is a Charge Coupled Device (CCD device) acronym, it is a semiconductor imaging device, the charge information stored in the CCD charge-coupled device, a synchronization signal required to control the transfer of one embodiment of a read to the charge transfer of information and reading the output clock control circuit and the need to have three different power match, the circuit is more complex.

CMOS is Complementary Metal-Oxide Semiconductor (complementary metal oxide semiconductor) acronym, and the same as in high-definition CCD camera can record light changes semiconductor, CMOS photoelectric sensor photoelectric conversion arise directly after the current (or voltage) signal, the signal read very simple, both features are as follows.

CCD charge-coupled device to be under the control of the synchronization clock in the unit of output bit by bit slower ;

 
Meanwhile · CMOS photoelectric sensor to collect light electrical signals can be removed , but also to handle the image information of each unit , the charge-coupled device CCD faster than many ;

· CCD charge-coupled device mostly need three power supply, large power consumption ;

· CMOS optical sensor using only one power supply , power consumption is very small , CMOS optical sensor has a great advantage in energy efficiency .

IP HD cameras "brain" : core processing chip

HD IPC design a lot , but the architecture point of view, mainly in two ways: First, the use of CCD / CMOS sensor as the image capture device , supporting the provision of image processing and encoding functions SoC chip ; Second , using the front camera module , as the image acquisition device , and an ASIC or DSP common encoded and transmitted. As the first flexible architecture , widely adopted manufacturers.

In image processing , there are three implementations : the first ISP program using a dedicated processing chip and coding part of the program more flexible , using a dedicated ISP chip good stability , to ensure the quality of the image ; second solution with integrated ISP code chip , the program flexibility inferior to the first scenario , and a dedicated ISP chip stability is high, but the image quality is generally high cost ; third option , such as the use of FPGA chip signal processing and coding functions the most flexible solution , but poor stability, highest cost, image quality is difficult to guarantee. Dedicated ISP program design flexible , cost-effective , can guarantee the quality of the image, suitable for high-definition IPC designs.