"Bob Parker"
** Only thing is, the required resolution is approx 2000 lines per inch while the linear scanning speed, at 18 inches per second, is about 100 times faster than a normal scanner.Be very nice if desktop scanners could do that.
....... Phil
I thought I was the only one here who stays up this late/early. :-)
Yeah, it would save a lot of time if your average flat-bed scanner could manage that!
Assuming that the figures we've been taking to be correct really are, it translates to about 36,000 rows of data/second going past the reader. That means a linear sensing array like that Fairchild one and its associated electronics would have about 27us to digitize each row. The frequency response of that sensor is quoted at 20MHz, which would seem to indicate it could easily respond to optical data going past at that speed. The reader assembly's a precise-looking thing. It shouldn't be too hard to make optics which can focus 2,000 lines/inch data bits onto a linear CCD array, should it? Your average digital camera's optics are sharply focussing an entire scene onto a sensor which is typically only about 6mm square. I'm not saying that I know for sure how the system works, but the linear sensor array idea looks practical as far as I can see.
Bob
I've just uploaded a pair of relevant images to my web space.
Bob
that chip that google found me (Fairchild CCD153A) can do a 20 MHz data rate, that comes out as about 39000 lines per second (if I'm reading the data sheet correctly), sufficient I think.
Bye. Jasen
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