I’ve been using scanners for a long time, but I’ve never given much thought to how they actually work. I guess I just assumed there was a tiny Fraggle in there taking a picture with a camera.
It turns out that while the Fraggle part may have been wishful thinking, the camera part is sort-of true. The component that does the actual conversion from a physical document to a digital image is called an image sensor.
Like anything else, there are different types of image sensors at different levels of quality. It can be hard to know what the difference is, but Kevin Neal from ABBYY posted a helpful reference to the Document Capture LinkedIn group.
Check out this Fujitsu newsletter and flip to Page 8. In the sidebar, there is a good description of the types of sensors: CCD, CIS, and CMOS.
Give the article a read, but in short:
- CCD: The best image quality, but takes more power. The ScanSnap S1500 uses this sensor, for example.
- CMOS: Good image quality but less expensive than the CCD. The Canon P–215 uses this.
- CIS: Still good image quality, but lower resolution and better power usage than the CCD. The ScanSnap S1300i, S1100 and Doxie Go use this one. It allows for much smaller scanners.
There you go, more than you ever needed to know about image sensors. As with anything else, you need to decide which is important to you.
(Photo by John.E.Robertson)