At 01:19 AM 6/19/01 -0700, Art wrote:
>
>
>rafeb wrote:
>
>
>> This technique is not original to Nikon; it's used in
>> sheet-fed paper scanners (eg. Visioneer PaperPort.)
>> Where I work they're refered to as CIS scanners
>> (Contact Image Sensor.)
>>
>
>I don't believe this is the same thing.
>
>As I understand it, a CIS is a different sensor than a CCD. It may well
>use a different light source, but I do not think the LED light source is
>a requirement.
You're right, the sensors are a very different sort
of layout, but they are typically used with LEDs
as illuminants. CIS sensors are typically used in
FAX machines, ultra-portable scanners, and in hand-held
scanners.
A CIS sensor doesn't use optics. The CCD cells are
physically arrayed along the width of the object being
scanned, and right up against its surface Ie., if
scanning a letter sized sheet, there are sensors all
along the 8.5" width of the sheet. Of course, the
sensors aren't all on one chip. The physics of the
sensor(s) is the same; they're still charge-coupled-
devices (CCDs).
The sensors used in film scanners are monolithic,
of course (ie., one chip.)
Even so, if you do a web search on "scanner LED
illumination" (try google) you'll find some non-
Nikon film scanners that use LED illumination.
One in particular was an APS-only film scanner
designed to fit in a standard hard-drive bay in
a PC. Possibly a rebranded Kodak unit. It seems
Kodak has a lot to say, also, about LED illumination
in scanners; there's a very interesting PDF at:
en/consumer/dls/ledTechnology.pdf
For a look at a typical CIS assembly, see:
14sensor/sensor2.html
(Both URLs deliberately broken into two parts.)
rafe b.
