Linear CCD Update

Just a quick update. I was going through some boxes that I haven’t unpacked since moving and I found the linear CCD I was experimenting with.

After reviewing some schematics I’d saved and reviewing some datasheets, I’m sort of back up to speed with where I left the project.

I managed to get some traces on my analogue oscilloscope that sort of match the datasheets but the relatively fast timings and the inability to store a trace on my oscilloscope was making things difficult. So, I took the board into work to use one of the good digital oscilloscopes in the workshop and I managed to get the following trace.

Yellow trace is the CCD output signal. Green trace is the transfer gate signal I was using as a trigger signal.

After performing a few tests I am not confident that I have all of the signals or the timing correct. Why I know this is because when I placed small pieces of black tape over the CCD’s lens, I was not seeing a decreases in signal intensity to match the number of pieces of black tape. Also, when I shaded a quarter of the CCD, the signal output for all the CCD’s pixels decreased in output value rather than the pixels that were shaded.

Anyway, I’m learning a few things about analogue electronics which is good. So far I’ve needed to improve my knowledge on op-amp circuits and I’ve been using a sample and hold circuit to help isolate the specific pixel output signal from the entire output waveform.

Anywho, I’m sure I’ll share more details as they arise.

Flatbed Scanner CCD Reverse Engineering

Probably about 12 years ago, I recovered the imaging sensor from an A4 flatbed scanner that had become obsolete. (I think its obsolescence was due to it having a parallel port interface and my family’s new computer didn’t have a parallel port) Apart from it not being able to communicate with a new computer, it still worked fine sadly. Fortunately, there were several useful components that I recovered from it including a stepper motor, v-belts and pulleys, CCFL light and the CCD.

Well, after all that time saying that one day I’ll get the CCD to work, the time has come.

CCD_board

Continue reading