Custom Booklight for the 505 (any interest?)

[aapezzuto]

I caved and got a shiny new 505 before my 2 500s have come in the mail. I am hoping this device can replace my wifes reb1100 (similar to the bookeen 1150). Because about 75% of her use is at night reading in bed the lack of back light is causing some problems. I am looking at hacking apart a LightWedge, to make a perfect fit light. To those who are not familiar the lightwedge it is a battery operated led book light. What is special about it is it has a special lens that keep light about 80% on the page it is over, and very little wasted stray light. To make my wife happy I will have to make this work no for us no matter what. What I want to know is info on if its worth my time to produce and sell extras. In that line if people could respond with questions, and answer the following questions based on the strength of your opinions on each...

• What is a good price for such a dedicated device?
• how long do the batteries need to last?
• should it include a charging circuit (recharge without removing batteries)?
• should it use standard size batteries (user replaceable and rechargeable)
• How bright does it need to be? (only in low light? on a train?)
• should it use a clip, adhesive, magnate??? (easily removable?)
• does the entire device (batteries etc) need to be hidden by the 505s cover?

I look forward to seeing what other people think!

[DrMoze]

I'd be interested. Standard batteries (rechargeable or regular) for travel. Built-in charger would be great. Clip-on would be optimal for me. Multiple brightness levels to conserve batteries.

BTW, does the standard wedgelight work ok with the Reader? I don't recall seeing anyone comment on this. (I'm sure people have tried though!)

[NatCh]

Originally Posted by DrMoze

BTW, does the standard wedgelight work ok with the Reader? I don't recall seeing anyone comment on this. (I'm sure people have tried though!)

It was kicked around quite a bit last year after the 500's launch. One fellow even did as aapezzuto's contemplating and hacked a paper back sized LW up to fit the Reader's display.

The standard LW (unmodified) works ... somewhat on the Reader. The problem is that it's too big to get it flush against the display, so you lose some of the effect.

A year ago, we organized an effort here to e-mail LightWedge asking them to create a LightWedge for the Reader, they were apparently reluctant to do so on an, as yet, unproven device.

With the increase in 6 inch devices, I wonder if it might be worth organizing another effort at it. Maybe they'd be swayed now.

[drgnbear]

I'd be interested.

I personally have been extremely happy with my Veriluxe light. Battery life is awful but it's worth keeping a pack of cheap AA batteries around to get the quality of light it has. I'd LOVE to see a light wedge hacked to use the Veriluxe bulb instead of led, but baring that I'd buy a lightwedge just to see if I get a better reading experience.

[obelix]

Originally Posted by aapezzuto

I am looking at hacking apart a LightWedge, to make a perfect fit light.

I did (a year ago). See a second half of the page:

http://www.msh-tools.com/ebook/frontlight.html

I've tried many different illuminators (including Verilux), but mine (LightWedge based) is absolutely the best! I'm using it almost every night.

The battery I use (GameBoy Advanced) is perfect. The charge lasts for about 3 Sony Redaer charges (several weeks). Current stabilization is a must. To be short, I believe my design is almost perfect (at least to me). The battery/electronics box on a clip is pretty convinient.

If you are thinking about commercial device, I think there is a better technology, but very hard to make it without special equipment. A plastic sheet with 10 micron scratches (triangular), seprated by 100 micron gaps. This design perfectly direct light to the page at the same time being transparent. In contrast to LightWedge, the thickness of the plate can be thin. This technology is used in some frontlight illumination displays. I was not able to get one to try.

I would pay for good illuminator (like mine, or the one described) as much as $200. Night reading for some people is 90% of reading (like me or my wife).

[aapezzuto]

Originally Posted by obelix

If you are thinking about commercial device, I think there is a better technology, but very hard to make it without special equipment. A plastic sheet with 10 micron scratches (triangular), seprated by 100 micron gaps. This design perfectly direct light to the page at the same time being transparent. In contrast to LightWedge, the thickness of the plate can be thin. This technology is used in some frontlight illumination displays. I was not able to get one to try.

Thats actually very interesting, if this has a special name that would be very helpful, like the flat lenses that have the etched rings are called something (I think bernell lenses)

My first version has a light wedge cut down to fit inside the resessed part of the reader, is running on 1 led, and 2 sr1220 3v cells. so far it is turning out well, but who knows what I will end up with. I will likely make 2 of them, and sell the second on e-bay to mack back some of my costs.

[NatCh]

Originally Posted by obelix

A plastic sheet with 10 micron scratches (triangular), seprated by 100 micron gaps. This design perfectly direct light to the page at the same time being transparent. In contrast to LightWedge, the thickness of the plate can be thin.

I'd really like to know more about that myself.

[obelix]

Originally Posted by NatCh

I'd really like to know more about that myself.

One of the patents:

http://www.google.com/patents?id=pkI...rooves#PPP1,M1

I also read (cannot find right now) some publication in one of the optics journal with calculations and experiment proving triangular grooves of 10 microns with 100 micron separation.

This technology was widely used, for example, in commercially available illuminators for GameBoy console by Nintendo (though the size was not that large as it needed).

I tried to make also similar plate myself by polishing the plastic with very fine sand paper. It scatters light well, but, unfortuantly irregular pattern with uncontrolable size of the grooves makes it not clear enough for comfortable reading.

Also, have a look at the dreams (?) here:

https://www.mobileread.com/forums/sho...9&postcount=11

[aapezzuto]

Im still looking for the generic term, I found the name of the other flat grooved optic that comes to mind. Fresnel Lens is what i was thinking of before. That monster can melt almost anything using solar power... what happens when you refocus almost 6ft^2 into a 1in^2 space? 738x the heat!!!!

The best idea i have come up with for replicating the concept is getting a piece of lexan and heating it, with something that has the sawtooth pateren on it (like overlaping strips of metal... but that is more .5mm every 3-4mm . Even if i could get a list of products that used this sort of lens, I could get the name probably (calling distributes for parts.)

[obelix]

Originally Posted by aapezzuto

Im still looking for the generic term, I found the name of the other flat grooved optic that comes to mind. Fresnel Lens is what i was thinking of before. That monster can melt almost anything using solar power... what happens when you refocus almost 6ft^2 into a 1in^2 space? 738x the heat!!!!

The best idea i have come up with for replicating the concept is getting a piece of lexan and heating it, with something that has the sawtooth pateren on it (like overlaping strips of metal... but that is more .5mm every 3-4mm . Even if i could get a list of products that used this sort of lens, I could get the name probably (calling distributes for parts.)

I dont think it can be done with the grooves more than a few micron size. I tried everything I could find (3d post cards (~0.2 mm grooves), Fresnel magnifiers (~0.2-1 mm groves) etc. They do perfect illumination, but grooved surface distort the screen. Grooves must be really small! Front light plate from Game Boy has a "rainbow" effect at small angles of view, this is because of diffraction/interference at small grooves (they are invisible at regular angles).

[aapezzuto]

I apoligise for my time away... I had twins (well my wife did) and they are doing well. so here is what I have learned in my testing:

• light wedges work, but provied very uneven light
• most LEDs that are bright enough to work use 3,5or6v
• polymer clay starts of really hard before you work it
• light channel or LGP (light guide plate) are common terms for what we have be talking about
• Lightwedge(tm) will warp at 275 degrees in under 5 min (thats the temp the polymer clay sets at)
• Keeping twins in diapers is expensive and I may need a benevolent benefactor to continue testing.

During this research I have found that certain electronic screens and large display boxes are the major use for this technology. It is frequently generically referred to as edge lighting. I did manage to build a working 3v prototype from a chunk of lightwedge and a SPDT switch... and a cute little LED, but it warped in the final stage of frame construction. I will be making another on unless I can get a hold of a superior material. I doubt that I will manage to attract any funding, but if you are desperate for a good 505 book light, and have a little money you want to throw at it, I am dedicated to getting one that looks nice and works well. Please PM me... or give me some Karma (im becoming a bit of a Karma whore!)

[aapezzuto]

I may have found a supplier for the LGP (light guide Plate) at a reasonable size for our application. I need some help from someone who knows about electronics, specifically surface mount LEDs, latching switches(digital), and board etching.

[carchase]

I'd definitely be interested in buying one at a reasonable price. Rechargeable is preferred.

[tichkiir]

I'd love to have the possibility of getting something like this. I'd prefer to have controllable levels of lighting for various circumstances and a battery that can keep up with the reader - either because it just lasts that long or because I can replace it as needed for longer run time.

[mwBarlow]

Originally Posted by aapezzuto

Thats actually very interesting, if this has a special name that would be very helpful, like the flat lenses that have the etched rings are called something (I think bernell lenses)

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

How does a Fresnel lens work?
http://www.howstuffworks.com/question244.htm