How CCD technology makes the world of difference to your scanning results
Epson scanners use the light sensitive capabilities of CCD chips to catch and convert the information contained in light into a digital file. What CCD brings to your photographic images is better picture quality, greater sensitivity, reduced image noise and better dynamic range.
What is the difference between CCD and CIS scanner technology?
This lies in the way light is sent, reflected, delivered and gathered by the sensor. On a flatbed scanner using CCD technology (Charge-Coupled Device), the light source, normally a cold cathode light, is reflected by the orginal, diverted by mirrors and gathered by a lens on to the sensor. This consists of light capturing CCD elements. In some cases the CCD elements may also have a micro-lens in front of every photodiode to gather light more effectively.
With CIS (Contact Image Sensor) technology, the light from RGB (red, green, blue) LEDs is reflected by the original. Light is sent directly through an array of lenses to the image sensor which can be either CCD or CMOS. There are advantages to both technologies. In general, CIS allows the construction of smaller sizes as well as lower power consumption, while CCD technology allows a higher depth of field, higher speed and signal noise ratio and better colour accuracy - so higher quality and productivity.
With the introduction of the new consumer models like the Epson Perfection V10 Epson has achieved the combination of high quality CCD scanning with an ultra thin design.
Why do we use a micro-lens system with the Epson Perfection scanners?
Each CCD sensor element - the photo diode - has a defined area that is sensitive to light. Ensuring that the light from the scan is directed to that sensitive spot increases the overall sensitivity of the system, which enhances productivity and reduces potential noise. This can be achieved by using a micro-lens system which allows gathering the light into the most sensitive part - the central portion of the photo diode.
What is Epson Double CCD technology?
The electric sensitivity (the ability to turn light into a voltage) of each CCD element is higher at the centre than at the edges. That’s why Epson scanners use a CCD sensor that consists of two CCD rows which are slightly shifted toward each other. This way a high resolution can be achieved while improving sensitivity of the entire system.
Why does a larger element mean higher sensitivity?
In principle, this can be compared to large and small paving stones. When rain starts to fall, a larger paving stone will be hit by more rain drops, because of its larger size. In the same way a larger sensor can collect more light, hence it is more sensitive. Higher sensitivity is a very important factor for the signal noise ratio and also results in higher scanning speed.