IMAGE SENSOR

An 'image sensor' is a device that converts a visual image to an electric signal. It is used chiefly in digital cameras and other imaging devices. It is usually an array of charge-coupled devices (CCD) or CMOS sensors such as active-pixel sensors.
There are several main types of color image sensors, differing by the means of the color separation mechanism:

★ 'Bayer sensor', low-cost and most common, using a Bayer filter that passes red, green, or blue light to selected pixels, forming interlaced grids sensitive to red, green, and blue. The image is then interpolated using a demosaicing algorithm.

★ 'Foveon X3 sensor', using an array of layered sensors where every pixel contains three stacked sensors sensitive to the individual colors.

★ '3CCD', using three discrete image sensors, with the color separation done by a dichroic prism. Considered the best quality, and generally more expensive than single-CCD sensors.

Contents

CCD Vs CMOS

Specialty sensors

See also

References

Leading Suppliers of Image Sensors

CCD Vs CMOS

Today, most digital still cameras use either a CCD images sensor or a CMOS sensor. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals.
A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.
A CMOS chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip converts the voltage to digital data.
Neither technology has a clear advantage in image quality. CMOS can potentially be implemented with fewer components, use less power and provide data faster than CCDs. CCD is a more mature technology and is in most respects the equal of CMOS.^[1]
[2]

Specialty sensors

Special sensors are used for various applications. The most important are the sensors for thermal imaging, creation of multi-spectral images, gamma cameras, sensor arrays for x-rays, and highly sensitive arrays for astronomy.

See also

★ Video camera tube

★ Semiconductor detector

★ Contact Image Sensor (CIS)

★ Charge-coupled device (CCD)

★ Active Pixel Sensor (MOS, CMOS)

References

1. [1] CCD Vs CMOS from Photonics Spectra 2001
2. [2] Sensors
By Vincent Bockaert

Leading Suppliers of Image Sensors

★ OmniVision Technologies, Inc.

★ Panavision SVI

★ TOSHIBA Semiconductor Company - Click "Products/Imaging Solutions"

★ STMicroelectronics Imaging Division

★ Micron Technology, IncCMOS Image Sensors

★ Galaxy Core, Inc CMOS Image Sensors