Contact Image Sensor

Contact Image Sensors are a relatively recent technological innovation in the field of optical flatbed scanners that are rapidly replacing CCDs in low power and portable applications. As the name implies, CIS's place the image sensor in near direct contact with the object to scanned in contrast to using mirrors to bounce light to a stationary sensor, as is the case in conventional CCD scanners. A CIS typically consists of linear array of detectors, covered by a focusing lens and flanked by Red, Green, and Blue LEDs for illumination. Usage of LEDs allows the CIS to be highly power efficient, with many scanners being powered through the minimal line voltage supplied via a USB connection. At the moment, CIS's generally produce images of inferior resolution and quality when compared to their CCD brethren, but, as the technology is still young, this is bound to change.