2006-12-16.ppt

Charge Coupled Devices—  Digital Cameras Instructor: Professor Sobolewski Prepared by: Huizi Diwu INDEX History Operation of CCDs How Digital Cameras Work? CCD vs CMOS History Although CCD was originally invented in 1969 by Willard Boyle and George Smith at ATT Bell Labs as a “semiconductor bubble” memory device, it is more intended to be used as an image sensor, which is the result of its advantage of light sensitivity. Operation of CCDs Surface Channel CCD (SCCD) Grounding the substrate and applying a significantly more positive voltage at one electrode than its neighbors form a pixel-----picture element. Charge is stored and transferred at the semiconductor surface in SCCD Some problem of interface-state trapping exist in SCCD. Has better charge-carrying capacity Buried Channel CCD (BCCD) A thin n-type region is formed on the surface of substrate Avoid the interface-state trapping Higher Speed but smaller charge carrying capacity Operation of CCDs Charge Transfer Process Charge Transfer Process Charge Transfer Process Charge Transfer Process How Digital Cameras Work? How Digital Cameras Work Bayer filter Look at the nearby information of a pixel to make very accurate guesses about the true color at a certain position The true color of a pixel can be determined by averaging the values of the vicinity pixels How Digital Cameras Work How Digital Cameras Work How Digital Cameras Work CCD vs CMOS Reference [1] Furumiya, M.; Hatano, K.; Murakami, I.; Kawasaki, T.; Ogawa, C.; Nakashiba,Y.: “A 1/3-in 1.3 M-pixel single-layer electrode CCD with a high-frame-rate skip mode”, IEEE Transactions on Electron Devices, Volume 48 Issue 9, pp 1915-1921, September 2001 [2] Philip Felber , “Charge-Coupled Devices” , Illinois Institute of Technology, May 2, 2002 Robert D. LaBelle and Sean D. Garvey, “Introduction to High Performance CCD Cameras” IEEE 1995. [3] Xiao-Wei TU and Bernard DUBUISSON “CCD Camera Model and its Physical Characteristics [6] C