Lens Disk idea

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Postby gary » Mon Dec 10, 2012 8:12 pm

M3DVQ wrote:
My point is that it's not natural at all. The dyes are selected precisely because they absorb the visible wavelengths. (no-one wants to buy clothes dyed a "colour" that you can't see, and outside of a few uses like ours, no-one wants to print that "colour" either)


Yes and what you say would make perfect sense IF black was being created by mixing CMY - however every inkjet printer I have ever seen has a separate black ink cartridge because mixing CMY is not very good at producing black - it it WAS being made by mixing CMY then it would explain everything.

As it is - surely they wouldn't choose a black dye that just happened to absorb the entire visible light spectrum and nothing else? If it is not deliberate - and I can't see why it would be - then it must be "natural" (more like supernatural if you ask me).
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Postby Harry Dalek » Mon Dec 10, 2012 8:49 pm

I tested news paper ink today that seemed to reflect not to bad off the white paper and not so well the Black , i then went back to my printer paper and tried this Permanent marker it seems to give a difference now between the white and black ,the white reflects and black not so well now thats what i want arrr i will try the marker on an encoder and see .
I think the shiny and white idea would give a better pulse strength wise but an uncut encoder would give a better correct pulse .
Heres the test of the gold and white encoder so thats works as you see .
I did by the way do the leaf test was ok but the leaf was shiny .
Attachments
Picture 072.avi
Permanent marker test
(1.9 MiB) Downloaded 126 times
Picture 074.jpg
Picture 074.jpg (76.39 KiB) Viewed 2708 times
Picture 069.avi
news paper ir test
(7.68 MiB) Downloaded 116 times
Picture 078.jpg
Testing the shiny gold white encoder have not hooked up the PLL wire yet
Picture 078.jpg (339.47 KiB) Viewed 2708 times
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Postby Harry Dalek » Tue Dec 11, 2012 6:45 pm

Well i did one last test today i have sacrificed a print out encoder , one of the black slots is painted with the permanent marker other not ....i think you can tell which Yakes am i bad at this !

In the photo the IR light is between the 2 slots and the light from the remote is close as between the 2 slots the permanent marker does not reflect as well must absorb the light where as the printer ink reflects almost as good as the white paper if you look at the video its shows it better .

Now i need a maker thats pen like i can keep in the lines then :shock:

Oh well my work on encoders over for a bit i will get back soldering rest of the camera back together .
Attachments
Picture 080.jpg
The printer ink reflects IR light about the same as the white printer paper
Picture 080.jpg (334.89 KiB) Viewed 2696 times
Picture 081.avi
Video shows my printer ink really is useless for an encoder
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Postby gary » Tue Dec 11, 2012 6:50 pm

Thanks Harry, you have gone to a great deal of effort and I appreciate it.

BTY your printer is an inkjet printer isn't it?
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Postby Harry Dalek » Tue Dec 11, 2012 7:28 pm

gary wrote:Thanks Harry, you have gone to a great deal of effort and I appreciate it.

BTY your printer is an inkjet printer isn't it?


Its interesting the encoder is a simple thing but boy it gave me trouble least i know a few ways to make it work now.

Theres my printer in the photo its a HP Photosmart C6180 yes i am pretty sure its an ink jet type...

I would like to look into if theres different black inks for it ...other wise i need to relearn colouring in the lines.
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HP_2.jpg
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Postby gary » Tue Dec 11, 2012 10:08 pm

Ok guys I have hijacked this thread enough and this will be my last post HERE on the subject. I am getting close, I think, to a solution, but I may yet open another thread if I deem it necessary.

Now if anyone is still reading this you may be saying what the hell is this guy going on about?

Well the issue basically is that I and many others have printed out encoders for NBTV sync and used them quite successfully. I, being the good Samaritan I am ;-) introduced Harry to what I believe to be a very simple and easily implemented sync detection system. Alas, for Harry it didn't work, and the fact it didn't work has cost both Harry and myself more time and effort than a more conventional detection system (a hole in the disk) would have taken.

*Nowhere* in the literature, that I am aware of, is there an explanation for why it doesn't work for Harry.

Eventually Graham came along and pointed out that he too had problems when printing out similar encoders (or whatever) on an INKJET printer. Well, I use a monochrome laser printer and so I said sorry I didn't realise it didn't work with with inkjet printers and we all carried on as if nothing had happened.

Well over time, and also because Harry has had to revert to cutting out encoders etc, which is really no easier than punching holes in the disk and having an opto fork etc. caused me to ponder more on the subject and I just couldn't believe that there could be a pigment/dye that just happened to absorb the entire visual spectrum, but annoyingly, didn't absorb the IR spectrum.

Now there are a number of ways to create black, one of them, indirectly explained by M3DVQ is to use a series of "notch" filters (CMY). This would explain the IR reflectivity because together the perform a perfect "notch" over the visible spectrum. The problem with that is, as is often the case, it is not so perfect in practice as it is in theory, and that method is rarely used (if at all) in an inkjet printer where black is produced by a separate ink cartridge (K).

So here we are, a laser printer toner (carbon black), and an inkjet ink/dye/pigment ALSO usually carbon black, behave differently - WTF? (I says to meself).

Now, I attach a graph which basically shows my quandary. It shows the response of carbon black and it indicates what I have previously been ranting about (ad nauseum to most I am sure). It is flat over the visible spectrum AND the IR spectrum.

Ok, ok, black ink may be made of something else I suppose (although why I can't guess as carbon black must be the cheapest ever thing to produce), AND - I said AND it *may* have that peculiar characteristic, quite unlike carbon black, of nulling out the visible spectrum but no part of it's adjacent spectrum - IR.

Well, to me that's quite a stretch, sorry.

The penny dropped with Harry's last post - his printer is a "photo" printer (Graham - can you confirm whether or not yours is also?).

I have found a reference that indicates that *digital photo printers* exhibit high IR reflectivity - why this is I am yet to determine but rest assured I will find out.

If I haven't already put you to sleep - you can go to bed now ;-)


PS: The image is from an article on the development of an IR absorbing ink - a topic unrelated to this matter - but the important thing is the carbon black ink graph.

PPS: I am also asserting that inkjet printers that *aren't* specifically photo printers should also work for these encoders.
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Postby gary » Tue Dec 11, 2012 10:26 pm

M3DVQ wrote:Dyes are generally invisible to infra red. It is apparently possible to get printer ink which does absorb infra red, but I suspect it's not cheap!


Sorry I missed this post. Yes you are perfectly correct - except for black ink - as I have mentioned elsewhere.
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Postby gary » Tue Dec 11, 2012 10:46 pm

On a final note (yes totally final)..

No one went for the *null* prize (can't imagine why):

Many people do not realise that light is merely a bandwidth (or sub spectrum) within the electromagnetic spectrum (which includes radio waves, micro waves, x-rays, gamma rays) that extends from (in terms of frequency) very small (x) to 1/1.616199(97)×10−35.

A special *null* prize to someone who can tell us how to determine x and why it is not constant, and what is the significance of the constant 1.616199(97)×10−35.


x is not constant because it represents the longest possible wavelength and that is the size of the universe - which is expanding.

The constant 1.616199(97)×10−35 is, of course, the Plank length and is the shortest measurable length possible.
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Postby M3DVQ » Wed Dec 12, 2012 4:32 am

gary wrote:
M3DVQ wrote:Dyes are generally invisible to infra red. It is apparently possible to get printer ink which does absorb infra red, but I suspect it's not cheap!


Sorry I missed this post. Yes you are perfectly correct - except for black ink - as I have mentioned elsewhere.


Well, as you've discovered, it depends on the ink!

I wonder if carbon black pigment ink is/was harder to refine to a grade suitable for inkjet use. I wonder if it depends on the type of print head too?

Some older black inkjet cartridges from HP, Epson, Lexmark and possible canon, were dye based. It appears that more modern ones should all be pigment but of course if you refill, or buy third party/refilled cartridges then all bets are off!
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Postby gary » Wed Dec 12, 2012 8:39 am

M3DVQ wrote:Well, as you've discovered, it depends on the ink!


Well we've always thought, and now thanks to Harry's efforts, empirically proven, that it is the ink - but the question has always been why is it the ink? Even if NOT using carbon black you would still expect a BLACK ink to absorb at least part of the IR spectrum. To NOT absorb part of the IR spectrum, to me, implies it has been specifically manufactured for that purpose. Under normal circumstances I can't see any need for doing that. From my research it appears that such an ink is used specifically for photographic printers - for what reason I have yet to determine.

At this point it time it also implies that a NON-photographic inkjet printer may not exhibit this somewhat unfortunate characteristic.

M3DVQ wrote:I wonder if carbon black pigment ink is/was harder to refine to a grade suitable for inkjet use. I wonder if it depends on the type of print head too?


I believe that was indeed the case. Modern inkjets are now more likely to use pigment inks because pigment inks are generally regarded as a better quality ink than dye based - it lasts longer etc.

M3DVQ wrote:Some older black inkjet cartridges from HP, Epson, Lexmark and possible canon, were dye based. It appears that more modern ones should all be pigment but of course if you refill, or buy third party/refilled cartridges then all bets are off!


Yes, I have read that using a pigment ink in a head designed for dye is certain to clog the jets up in quick time. I would imagine if you did the reverse smudging and/or leaking would occur.
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Postby Harry Dalek » Wed Dec 12, 2012 4:49 pm

Gary no worries about talking encoders here don't want to bore any one but i think there is at least 3 of us are trying to understand it .

Another thing that has come to mind i tried ,i tried printing transparent plastic sheet but found the ink does not stick or dry well on it ,it still would not have worked due to the ink but if a laser printer works ? it might work like my dvd cut out encoders but with a sharper pulse due to the reflective plastic part.

Reading about the carbon black used in laser printers ,i have pulled 2 of these type printers to bits as i recall the stuff they used is a dust or powder no ink at all dry powder..i think there were other colours but a dark green powder went very where on my shed floor ...nothing like a leaf blower to clean your shed quick :wink:
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Postby AncientBrit » Wed Dec 12, 2012 6:37 pm

Quick reply to Gary.

My printer is an HP Deskjet 1200, A3 inkjet.
Separate cartidges for black and colour.
Not advertised as "photo"

Haven't tried an IR pickup with a 'strobe' disc printed on this printer but can confirm that a testcard printed on it is nearly invisible to the club's dome photocell.

Cheers,

Graham
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Postby gary » Wed Dec 12, 2012 7:15 pm

@Harry - Thanks Harry, yes lasers and photocopiers us a dry toner powder which is actually *melted* on to the surface.

@Graham Thanks Graham, I assume that's with an IR source on the test card? Well since I posted the "photo" revelation I have found further sites that indicate that all inkjets exhibit the problem. Some have suggested the ink is actually *transparent* and the reflection is off the underlying white paper - an interesting thought.

I have been unable to locate a second source re the photo ink being the culprit for confirmation and the source has failed to respond to a request for more information.

So for now it seems I have to be content that it's "just one of those things". I still think it is damn strange though.
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Postby Steve Anderson » Wed Dec 12, 2012 8:42 pm

Unless there's some compelling reason not to do so why not use a visible light LED/photo-detector arrangement? Say red where silicon is its most sensitive in the visible part of the spectrum. OK, you'll have to screen out at least most of the ambient light and pre-assembled devices aren't available, but it should be a go-er.

I recall the BVU series of Sony U-Matic video recorders which used visible light detectors, when you took the top cover off for servicing the thing would either go haywire or simply lock-up. It did work otherwise though.

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Postby gary » Wed Dec 12, 2012 8:59 pm

Yes that is an option but:

a) we have the ir sensor
b) as you have mentioned there is the stray light issue
c) providing toner is used there is not an issue with performance

In Harry's case he only has to take his inkjet printout to his local library or photoshop or whatever and get a few photocopies and he is sweet.

For me it's just the annoyance of having recommended the process as one that is easy to implement (which it is) and then wasting time by not realising that inkjet black ink is either IR reflective or IR transparent.

It is even more annoying to me as this condition is unintuitive and I can't find a scrap of information as to why it is so. It's doing me head in son.
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