Re: Measuring Press Targets
Re: Measuring Press Targets
- Subject: Re: Measuring Press Targets
- From: Roger Breton <email@hidden>
- Date: Thu, 31 Jan 2008 21:39:39 -0500
Bill,
I ran into this situation many times with low contrast P2Px targets. The
trick is to darken the boudaries between the patches with a black felt pen
or scratch the substrate to create a white line between dark patches. Your
last row probably does not offer enough contrast for the instrument to
discriminate between some patches and errors out. I don't know what the
treshold is for the patches to be recognized but all I can say is this
technique saved my ass everytime. You'll probably remember using this
technique with the DTP41 in the past -- same idea. This may not solve your
problem in your particular instance but I remember the frustration I
experienced measuring low contrast targets on the iO and everytime, either
applying some liquid paper to create a white line between the patches of
drawing thick black line between some other patches solved the problem for
me everytime. I'd be curious to take a look at those pesky P2P targets if
you'd care to mail me a couple.
Regards,
>
> Would someone please explain what goes on when an iO is measuring a P2P target
> using MeasureTool. My iO seems to get
> "stuck" on the seventh row of the P2P target when measuring in strip mode and
> returns after a few passes to the home
> position with the usual rejection message box. This happens even if I select
> low resolution mode.
>
> The seventh row is a rather flat looking row with little difference in
> contrast between the patches. All patches are separated
> by a yellow stripe except one which is bordered by a green stripe. I am a
> flexo printer and while I have to deal with some
> gearmarking, not all of my samples have gear marks and in fact the few
> gearmarks that do show are in rows that read
> great in strip mode.
>
> I am curious to know if anyone knows why it stops reading on the seventh row
> instead of just reading through it and giving
> me whatever results it found. Is there some patch color checking going on? Is
> it possible that the green borders on the one
> patch are too close to the patch color and the iO does know where to "break"
> it measuring? On some of the targets this row
> will read and on others it won't, yet visually they look no different.
> Sometimes when the seventh row reads the tenth row
> will not and it is also rather flat in contrast between the patches.
>
> I have tried cutting away the green stripes on row seven thinking contrast
> might be the problem, but it did not help. I have
> not tried making them black, nor have I tried this on the yellow stripes
> dividers in row seven. Interesting that both problem
> rows, seven and ten, have yellow stripes dividing the patches.
>
> Thank you to all that respond.
>
> -Bill-
Roger Breton
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