Custom Booklight for the 505 (any interest?)

[rocket733]

While looking at the LGP technology it occurs to me that's what they use behind the screens of current lcd monitors. I wonder if it's clear enough to read through? Next time I got home I'll look around for an old laptop to take apart and test, that might be a cheap way to get materials.

[NatCh]

Somehow the idea of cannibalizing old laptops to make reading lights for e-ink strikes me as terribly funny.

That's not to suggest I think it's not a good idea, I'm very interested in what you learn from your explorations, rocket733. Oh, yeah: Welcome to MobileRead.

[rocket733]

Lol now I certainly see the humor there.

[aapezzuto]

My wife was laughing at me when I started this project... I went out and bought a shiny new lightwedge to canabalise for its parts... then I went to frys electronics... for more victoms. She told me "Your the only person I know who buys things for the stuff their made of."

As far as LGP, that is the most generic term for what we are looking for. I have found a distributer that is willing to send me some samples... I just have to save up the money for the shipping costs, and my new twins are making that hard to do. I have linked to some pages that may be helpful at that companies website, and whatever else I could find that might help...

• crystal light boxes
• advertising/poster light boxes
• cell phone front light LGPs
• page on light tech, Light Guides are at the very bottom.

[aapezzuto]

Originally Posted by mwBarlow

They're called Fresnel Lenses and that might be a pretty good place to start investigating...

Thats what i thought at first as well, but thats not what this is. First a frensnel lense would make it look bigger, by refracting light in a circular pattern. and edge lit fresnel lense will not work very well (I have a 9x12 one about 2 ft from me from my first round of research about 4 months ago).

The group of devices that I have been looking at are described as light guides. That general term is any device that can in a slim form factor rotate a light source 90 degrees. These are bipolar transparent lightguides that take advantage of something similar to one way glass. There are other light guide designs that use small etched grooves to cause their refraction, while others still are using some strange grown crystline stuff. There are even talks of using the laser tech for polar light guides (like what is behind your LCD).

The lightwedge it using 2 principals, the major is its geometry, light bounces around in non parelle area till it can escape.. by then its all over the place... and second they have "tempered" the plastic to give it an optical bias towards guiding light out... but about 80+ % of the work is being done by the geometry.

So... what I have so far:
parts for 2 cost about 40$, and it would take me about 5-8 hours to manufacture 2 of them properly... still getting the kinks out of the current design.

These are half built, but i wanted to test some stuff out... That one of it lit up is with just one LED, to make sure the holes I drilled were letting enough light through.

[Icarusbop]

This is looking great so far...
If you painted the edges of the light guide with a reflective paint (chrome plasticote??) that would keep the light from leaking out around the edges, and make more of it escape through the back to the display. making it more efficient.
maybe.....

[Penforhire]

Count me in as interested. If you don't do it perhaps LightWedge could be petitioned for a custom model?

By the way, how much might this device weigh? I've never handled a LightWedge but the concept looked perfect.

[Greg G]

I am intersted as well! I'm so tired of wearing my headlamp to read at night and my wife is not so thrilled with that solution either.

-Greg

[NatCh]

It looks pretty good, how readable to you find it to be?

One thing I thought about trying was to "rough" up the "down" side with fine steel wool or sandpaper, to encourage the light to come out that side. What difference do you think that might make?

Originally Posted by Penforhire

If you don't do it perhaps LightWedge could be petitioned for a custom model?

Or perhaps even Sony directly ....

[Prospect]

This is very interesting!

[badgoodDeb]

That DOES look neat! Hopefully, you'll make them so they also fit the Kindle, or other devices with the same screen size. You'd have a bigger market then. (You, or whoever manufactures them).

Got any online pics of these rumored twins? (some of us love to look at baby pics). I don't imagine the two babies pictured between the fingertips in your icon are YOUR twins.

[Penforhire]

From my understanding of the lightwedge principle you really don't want to rough up either side of the wedge. You have to read through the whole wedge so any optic distortion, dispersion, or absorption is a bad thing (like roughing up or scratching my glasses). This sounded like one of the long term weaknesses of the wedge. Accumulation of scratches will eventually become distracting.

[aapezzuto]

Originally Posted by Penforhire

Accumulation of scratches will eventually become distracting.

Think of it as a luminescent screen protector. Scratches are annoying with the lightwedge, but it is a decent material, and it is only getting scratched at times when the screen would be in similar peril.

I'm about 90% done, i need to make a metal battery cover, drill and tap 2 holes, and perhaps seal the paint.

The 2-3mm edges have proved to be a minor problem with some books, as they hit the margin just barely... In production I may try at lessen this to 1mm. The edges are covered with reflective tinfoil tape, then painted. The top is shaped, and then extra components were "shaped" by covering them with hot glue, and then masking tape. It looks pretty sharp unless you start trying to dissect it for flaws... and it still fits like a glove!

So what is a fair price for 20-30$ in materials and 3-4 hours of time?

ps(once im done i might run some battery testing to see how long they last... I can tell you it will be more than 10 hours, but i dont know how long...)

[SurgE]

any pics of your light on top of a reader?

[NatCh]

Originally Posted by SurgE

any pics of your light on top of a reader?

There's the one in post #20.