Author Topic: touch-tip IR pens and friction  (Read 9275 times)

Offline Fastolfe

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on: February 24, 2009, 06:57:54 AM
I made me a pressure-sensitive IR pen the other day and it works quite well, but after only light use only on very smooth white boards, the tip of the LED is flattened and abraded. It doesn't even require a lot of force to light up the LED (about 50g), but I suppose it gets repetitive shocks on its tip when writing normally, and drawing long lines a bit fast really sandpapers it, even on smooth surfaces.

I'm thinking of glueing something at the tip of the led, such as a chip of rounded glass from an old miniature lightbulb, but if I remember correctly, glass reflects IRs, so it may not be such a good idea. Or I could glue a piece of some other, harder material.

How do you guys cope with LED abrasion? It took me a couple of hours to make this particular pen, and it's really nice and reliable, so I hate to see it waste away so fast.



Offline benpaddlejones

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Reply #1 on: February 24, 2009, 03:39:01 PM
Fastolfe
You must be usinga  rough surface?

Two choices, put some cardboard over your surface or put a thin film of hot glue on your IR-Led, will disperse IR and may even improve the quality of your tracking.

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Offline Fastolfe

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Reply #2 on: February 24, 2009, 05:20:19 PM
Fastolfe
You must be usinga  rough surface?

I only use that pen on very smooth, hard, real whiteboards. Whenever it looks remotely scratchy, or if the surface causes too much drag, I revert to another pen with a side switch


Two choices, put some cardboard over your surface

I can't really do that, I usually use my whiteboard setup on site at customers',  so I'm not going to tape cardboard all over their whiteboards :-) Not to mention, it might not look very classy (my company sells luxury products).

or put a thin film of hot glue on your IR-Led, will disperse IR and may even improve the quality of your tracking.

I'll try that, thanks. I'm not sure how the pen will feel like though, as the hot glue I use seems soft and slightly sticky even when cold.



Offline skimmer

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Reply #3 on: February 24, 2009, 06:57:02 PM
I've been using a pressure tip pen.  I haven't logged that much time with it, perhaps in total 15 hours of continual use if I add it all together.  I haven't noticed any abrasion as of yet.  50 g of force seems like a bit much.  My pen can't weigh much more than 25 g and its own weight easily activates the LED.  I've been using a 1/8" sheet of melamine surfaced fiber board taped onto a black board.  It has a slightly textured surface, which I think actually helps reduce friction. 



Offline benpaddlejones

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Reply #4 on: February 24, 2009, 07:47:39 PM
Fastolfe
Some 24hr arildite (an epoxy resin) will give you a hard feel.

benpaddlejones :)


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Offline isashach

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Reply #5 on: March 09, 2009, 03:18:03 PM
So you mean that "The Groove" pen that's advertised all over here has the same problem  :o?



Offline benpaddlejones

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Reply #6 on: March 09, 2009, 08:00:15 PM
isashach
Please read before posting!

The problem is not the Pen the problem is the surface so yes the groove and every other pen advertised all over this forum with have a problem because the problem is the surface!

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Offline isashach

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Reply #7 on: March 10, 2009, 12:31:01 PM
Yes I know it's the surface, but honestly, I ain't gonna put ugly cardboard over my tv!



Offline benpaddlejones

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Reply #8 on: March 10, 2009, 04:26:29 PM
isashach
A TV has a smooth surface??? So its not a problem for your setup. However your problem is that a) will scratch your screen & b) too much point pressure will break the LCD.

I suggest you hop on ebay do some searching and you will find you can buy screen protetcor material (like used for PDA's & digital cameras, etc) in large sheets. Just put on your TV screen will run smooth, no scratching and disperse pressure so less likely to damage your screen.

benpaddlejones :)


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