SONY EXVIEW HAD CCD ICX249AL

CCD stands for a Charge-Coupled Device (or sometimes Color-Capture Device), and it is an image sensor used in digital cameras. A CCD is an integrated circuit that contains an array of linked, or coupled, light-sensitive capacitors.

An image is projected by a lens on the capacitor array, causing each capacitor to accumulate an electric charge proportional to the light intensity at that location. A one-dimensional array, used in line-scan cameras, captures a single slice of the image, while a two-dimensional array, used in video and still cameras, captures the whole image or a rectangular portion of it. Once the array has been exposed to the image, a control circuit causes each capacitor to transfer its contents to its neighbour. The last capacitor in the array dumps its charge into an amplifier that converts the charge into a voltage. By repeating this process, the control circuit converts the entire contents of the array to a varying voltage, which it samples, digitizes and stores in memory. Stored images can be transferred to a printer, storage device or video display. CCDs are also widely used as sensors for astronomical telescopes, and night vision devices.

The EXview HAD CCD is a CCD structure that is highly sensitive in the near Infrared Light Region, which is invisible to the human eye. It is very popular in video cameras that are designed to work in low light conditions, most commonly used in the security and surveillance industries.

In traditional CCD structure, light in the near infrared light region, which has long wavelengths, is converted into photoelectricity deep in the semiconductor's silicon, which means that sensors are incapable of efficiently gathering the charge which has undergone photoelectric conversion. The EXview HAD CCD structure allows charge due to infrared light (which was ineffective in traditional CCDs) to be used as video information.

The diagram below compares the spectral sensitivity characteristics of the EXview with conventional CCDs. As opposed to conventional CCDs, which exhibit a curve that peaks at a wavelength of about 500nm and decreases as the wavelength increases, the EXview provides increased sensitivity to the near infrared light regions. Wavelength (X axis), is given in nanometers. However, as the diagram does not provide any calibration on the Sensitivity axis, it is impossible to get any real information from this diagram. Bear in mind that this diagram was produced by Sony, who make and sell the EXview.


The next diagram gives some more definite data on the capabilities of the EXview.


I am not sure what unit the light sensitivity is measured in here. Perhaps it is the maximum charge produced by the CCD in response to light, measured in micro Volts??

I think that "Smear" is a reference to the CCD's signal to noise capability.