Author Topic: please help! why isn't my wiimote whiteboard so great on large screen???  (Read 6989 times)

Offline dsgclan

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I have played with the wiimote board for a while on my 22" LCD monitor, today I've got a new projector and started to make a real whiteboard out of it, but it did not work so great, when I used it on my 22" monitor, the wiimote is placed about 1m to the screen and ir pen, it worked very well, I can draw continous lines on the monitor without broken, and maybe 99 out of 100 times the click worked; but today when I used it on a 60" projection screen with the wiimote being placed 2m from the screen, I could not draw any continouse line, the line becomes many small sections, it's broken everywhere, and maybe 2 out of 5 times the click does not work, it is very disappionting, I had high hope on the white board but now I'm quite dispressed....

Can benpaddlejones or anyone else who's used wiimote on a large projection screen tell me please, how does it work on your big screens (60" or larger)? can you draw smooth and good continuous lines? where could I possibly go wrong? I have made 3 pens, 2 with some generic IR LED's I found in local electronic market, 1 is Vashey 7300, I could not find the 6400 everyone is using, but the rating of the 7300 seems just fine, however my favorite LED is the generic LED, I drive it with 200mA and it is very bright, I am not sure if the LED is the reason.

Could it be my wiimote? maybe I'm so unfortunate that I got a under-performed WIIMOTE? I don't know because this is the only one I have.

But if anyone can tell me and assure me that WIIMOTE whiteboard is not supposed to work like this, it is supposed to work well on a 60" or 70" or larger screen, I can just buy a new wiimote or experiment with new LED's further more with confidence, thank you!



Offline Descalzo

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When I had problems like that, it was because I was using a bad pen.  I switched to a pen made from a battery holder and a better LED, with every connection soldered, and my problems went away.  So that's where I'd start.



Offline benpaddlejones

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dsgclan
If you can have an underperforming wiimote what does an overperforming wiimote do ???

I agree with descalzo, most likley your IR-Pen.

Could you please post:
IR-Led: (manufactuer)
Power Source: (Battery size and qty)
Switch type: (link to manufactuer or similar)
Resistor: (if you have on ewhat size)

Benpaddlejones :)


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Offline jamesKL

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well according to my experience, the larger the screen, the further away the wiimote is. But wiimote has a limited distance of about 3m, after the limited distance, the wiimote wont be able to track IR source clearly as less than 3m. sorry for my english:)



Offline benpaddlejones

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JamesKL
If your IR-source is good enough wiimote will work at ranges of 4m+ without a problem, so at 2m should be no problems hence why I suggest it is most likely an IR-source problem.

benpaddlejones :)


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Offline jamesKL

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oo sry i forgot to see its 2m, if 2m its alright... So the problem might be the surface of ur projector screen, well maybe i not sure cause some projector screen allow light to pass through, thus it does not reflect the ir much and it causes ur problem.

Next i could think is that u r blocking it, but this possiblity cant be high so... can forget it lol

Last could be IR source problem, change it into a new battery and test




Offline dsgclan

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Thank you all for the fast replies!

To answer Benpaddlejones's questions first:
IR-Led: (manufactuer) ---- Vishay TSAL 7600, (spec at: http://www.vishay.com/docs/81015/tsal7600.pdf), I can't find any difference of it with Vishay 6400, I suspect 7600 is the same or update version as vishay 6400?
Power Source: (Battery size and qty)  --- 2x 1.2V rechargeable AAA batteries that give 2.4V
Switch type: (link to manufactuer or similar) --- it's a generic switch, this can't be the reason because even if I skip the switch and solder the wires together the line still breaks as before.
Resistor: (if you have on ewhat size) --- it's a 3 ohms cement resistor, generic.

I did more tests today, this is what I found out:

I tested wiimote more at 1.8m distance from projection screen, when I had the LED facing the wiimote and draw a continuous line in the air, the line was perfect and it was not broken at all, but when I drew on the projection screen with the butt of the pen facing wiimote, the line broke sometimes, but not too often, but it did happen here or there, I have attached a schematic explaining it in details, the scratch lines shown on the schematic were the actual images I got from Paint.

Then I did more tests at a 3m distance, it did almost the same, when LED faces wiimote, everything is perfect, when the butt faces wiimote, the line breaks, but the breaks do not seem to happen more often at 3m distance.

And I have also found that the actual viewing angle of my wiimote is only 31 degree rather than 40 or 45 degree as some people have claimed.

So can you please help me with the following questions:

1) when you draw on a large projection screen with wiimote placed 2m or 3m away, with the butt of pen facing the wiimote, is there any broken line at all? or it is as perfect as when the LED faces wiimote?

2) If your wiimote never looses track as I've experienced, what could be the problem of my pen? the batteries are fully charged, the vishay 7600 seems fine, could it be that my projection screen does not reflect much IR light as your screen does?

3) What is the actual viewing angel of your wiimote?

Please see the following shematic. Thanks for the help!

I don't know how to attach a pic on the post so I've posted it on a website please view the schematic at the following link:

http://www.bccrental.com/images/my%20question.jpg




Offline benpaddlejones

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dsgclan
I think a number of issues at play:
1.
On face value the IR-Leds look the same with some minor but important differences. The Relative Radiant Intensity vs. Angular Displacement graph shows the emitted IR-Light from the TSAL7600 will be more dispersed over a wider angle. The TSAL6400 is more focused in a slightly narrower angle. Making it easier for the Wiimote to track. Whilst a subtle difference this is amplified at distance.

2.
Your view surface may be a low glare amplifying above problem.

3.
Low tracking utilsation, what percentage are you getting after calibration? If below 40% you may find this again further amplifies the first issue.

4.
Incorrect resistor, I calculate your required resistor as "a 1/4W or greater 12 ohm resistor, brown red black."

I suggest trying a few different surfaces and making sure you get a tracking utilisation of over 50%, if this fails then you need a TSAL6400 or TSAL5300.

Benpaddlejones :)


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Offline dsgclan

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Hi Benpaddlejones:

1.
On face value the IR-Leds look the same with some minor but important differences. The Relative Radiant Intensity vs. Angular Displacement graph shows the emitted IR-Light from the TSAL7600 will be more dispersed over a wider angle. The TSAL6400 is more focused in a slightly narrower angle. Making it easier for the Wiimote to track. Whilst a subtle difference this is amplified at distance.

-----Yes you are correct, I don't know much about LED or photoelectronic, I will try to get TSAL6400, do you know where I can buy them in the US? I can't find them here in China but I can ask my friend in the US to buy some LED's for me.

Speaking of dispersed light, I originally thought it would be a good idea to install the LED inside the pen, and use a small glass stick to channel the IR light to the tip of the pen, and maybe polish the glass tip so it can disperse the light in a wider angel and help the wiimote see it from the back, I have not experimented it yet, but if you say it is not good to disperse IR light, maybe this will only make it harder to be seen?

So what is the mechanism that wiimote sees the ir light from almost the opposite direction of the pen tip, it does not see the light directly from the LED, but the light reflected by the writting surface?

2.
Your view surface may be a low glare amplifying above problem.
-- yes this is maybe true, I will try on a different screen, in your experience, does projection screen for beamer reflect IR light well?

3.
Low tracking utilsation, what percentage are you getting after calibration? If below 40% you may find this again further amplifies the first issue.
--- The tracking utilisation was very good, Boon Jin's software shows 84% of utilisation so this is not the reason.

4.
Incorrect resistor, I calculate your required resistor as "a 1/4W or greater 12 ohm resistor, brown red black."
--- Thanks, I had a friend of me calculate the resistor for me, I will take your advice and test it again!

By the way, when you draw on a 60" or larger whiteboard, the line never breaks even when you draw in the edge areas?

Cheers



Offline benpaddlejones

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dsgclan
I can't find them here in China but I can ask my friend in the US to buy some LED's for me.
http://cn.farnell.com/jsp/home/homepage.jsp

Speaking of dispersed light, I originally thought it would be a good idea to install the LED inside the pen, and use a small glass stick to channel the IR light to the tip of the pen, and maybe polish the glass tip so it can disperse the light in a wider angel and help the wiimote see it from the back, I have not experimented it yet, but if you say it is not good to disperse IR light, maybe this will only make it harder to be seen?
A little research ha sgone into this, but needs more. Perhaps you can contribute? Sounds like you have a very good idea!
http://www.wiimoteproject.com/ir-pens/how-well-does-diffusing-the-led-work/

So what is the mechanism that wiimote sees the ir light from almost the opposite direction of the pen tip, it does not see the light directly from the LED, but the light reflected by the writting surface?
It actaully sees either or both. If IR-Pen is touching surface then it will detect as 1 IR-Blob. If far enough apart (Pen away from board) will create erroneous results.

-- yes this is maybe true, I will try on a different screen, in your experience, does projection screen for beamer reflect IR light well?
What do you mean by a beamer?

Low tracking utilsation, what percentage are you getting after calibration? If below 40% you may find this again further amplifies the first issue.
--- The tracking utilisation was very good, Boon Jin's software shows 84% of utilisation so this is not the reason.
Thats great calibration!

By the way, when you draw on a 60" or larger whiteboard, the line never breaks even when you draw in the edge areas?
Works perfect even when bigger!

benpaddlejones :)


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Offline dsgclan

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Hi

1) I can't find them here in China but I can ask my friend in the US to buy some LED's for me.
http://cn.farnell.com/jsp/home/homepage.jsp
---- Ya actually this is where I bought the TSAL7600 LED's, Farnell has stopped stocking TSAL6400, I've found TSAL6400 at this online shop: http://www.newark.com/jsp/search/browse.jsp;jsessionid=RJHGB5WFZXZROCXDUZ0G4IQ?N=0&Ntk=gensearch_001&Ntt=TSAL6400&Ntx=&&_requestid=289302
The funny thing is, there are 2 LEDs with the same name TSAL6400, I believe they are the same LED's being added again by mistake, but to make sure I don't buy the wrong LED's all the way from US, can you please take a look:
http://www.newark.com/95B4859/optoelectronics/product.us0?sku=vishay-semiconductor-tsal6400   --- the spec on the page says 1A, but the PDF datasheet says 100mA, I guess it's a mistake on the webpage?
http://www.newark.com/34M8851/optoelectronics/product.us0?sku=vishay-tsal6400 --- the spec on this page says 100mA


2)
A little research ha sgone into this, but needs more. Perhaps you can contribute? Sounds like you have a very good idea!
http://www.wiimoteproject.com/ir-pens/how-well-does-diffusing-the-led-work/
---- Thanks for the info, it seems the only way to find out the result is to do some tests, I will certainly let you know how it goes when I've tested my idea!

3) yes this is maybe true, I will try on a different screen, in your experience, does projection screen for beamer reflect IR light well?
What do you mean by a beamer?
--- I mean projector, does the normal projection screens for projectors (you know, the piece of white cloth) reflect IR light well, and thus improves the functionality of the pen?

4) By the way, when you draw on a 60" or larger whiteboard, the line never breaks even when you draw in the edge areas?
Works perfect even when bigger!
--- Thanks, this is encouraging!



Offline benpaddlejones

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dsgclan
Newark looks identical to Farnell? The website I sent you is for the China branch of Farnell, they should import from UK stocks as that is where the Australian Farnell imports from. Same website, same part numbers maybe they have merged??? 1A = 100ma, they are only stocking product for 1 code so go with that one.

Every screen & whiteboard is different. To tell you the truth I have used on proberbly 30+ different surfaces including "low glare" and never had a problem. But you need to make sure the wiimote is never blocked from viewing the IR-pen too. This includes how you hold the pen.

benpaddlejones :)


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Offline dsgclan

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Hi benpaddlejones, yes I realized too that FARNNEL and newark are the same company, I think I will first try it on different projection surface and change the resistor as per your suggestion "a 1/4W or greater 12 ohm resistor, brown red black.", if it still does not work well I will order the 6400 LED's.

I understand that wiimote can never be blocked, so I think in future I will install it on ceiling with my projector, and make a longer pen.

Will keep you updated of how it goes, and I may have other questions later :)

Thanks again!