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Rohinni: Paper-thin LED lighting (rohinni.com)
180 points by fpp on Nov 25, 2014 | hide | past | web | favorite | 71 comments

Nth Degree Technologies invented this product. http://www.nthdegreetech.com/

Here is one relevant patent: http://www.freepatentsonline.com/8846457.html

Here is an album of various pictures taken earlier this fall (2014), and also just a minute ago with two pieces I had around the house: http://imgur.com/a/nBB5r

The technology is several things: it is real, it is sufficiently bright to stand up to daylight conditions, and it is mass-producible. It has raised interest from various industry sectors.

Lastly, this technology is not the work of Rohinni. They bought some pieces from Nth Degree, and what their business plan is, who knows. They did not invent it, legally cannot produce it, and it is doubtful they have the the technical knowhow to do so anyway.

In short, Rohinni is taking credit for a product they did not make.

> Lastly, this technology is not the work of Rohinni. They bought some pieces from Nth Degree, and what their business plan is, who knows. They did not invent it, legally cannot produce it, and it is doubtful they have the the technical knowhow to do so anyway.

Well, these seem like some pretty definite claims that should be easy to back up with evidence?

I'd say they are rather extraordinary claims, given the differences between the Nth Degree prototypes and the Rohinni prototype shown on the website.

Nth Degree's product honestly looks far more plausible, given its unusual characteristics (speckled luminance distribution, blue cast, restriction to clearly separated strips). It's considerably harder to find Rohinni's compromise-free prototype credible, with its consistent, diffuse, apparently-broad-spectrum light. But that just makes it even harder to believe an accusation that they ordered a few Nth Degree strips and went to town with them.

I've only seen pictures, but it seems plausible to be able to take Nth degree strips and add some kind of thin diffusion film over the surface, to remove the speckled look. Certain materials can also absorb blue and re-radiate multi-spectrum light.

Plenty of companies sell a product where the technology is licensed from another vendor and the manufacturer of record applies some design, QA, and marketing to it. Foxconn manufactures Apple computers, all of the celebrity endorsed perfumes come from the same few manufacturers, lots of phone companies source entire models from ODMs, etc.

Rohinni has a strictly better marketing campaign and more compelling webpage, and only requires a single email to get in touch. Your website is hard to navigate and asks for too much information to get in touch.

Neither company has a "Buy product now!" button.

The tie goes to Rohinni (even if their team photo looks kind of try-hard).

I know this is discouraging to hear, but I'm certain that you aren't the first company to ponder flat lighting on paper--moreover, your product appears to have a cool light pattern that doesn't actually match the use case of "I need a flat even diffuse lighting that doesn't look like a predator blood spray".

Those photos are wicked cool and very beautiful in their way too (reminds me of a star field). Thanks for sharing.

"Rohini" is the Indian name of a constellation, so you're not the first to make the connection :)

let's talk

How do you know that Nth Degree Technologies is one and the same as Rohinni? Searching and reading through all the articles I was not able to establish any link between the two companies.

He seems to be asserting that they are _not_ the same entity.

Nothing about this seems plausible to me. I do research on LED technologies though I can't speak about this specifically because they don't seem to have released any technical details whatsoever, but that's part of what makes me so skeptical. The panels they present are so bright, so uniform (both in colour and intensity), so thin and flexible–and they claim they'll be able to mass produce them too? Whatever they've got, I'd be very surprised if they manage to scale it, let alone for it to be "in the wild around the middle of 2015". I'd be very happy to be proven wrong of course!

I think in cases like this photoshop mockups (assuming that's what they are) can do more harm than good for setting expectations that might not be realistic.

We also develop since 2.5 years a thin backlight LED lighting technology and do observe the market closely. I am in the same boat here with lots of skepticism at least comparing to the photoshop pictures and expectations set. As the articles says it is some ink combined with LED lights, which will require some thickness as there is a silicon, die attach, some sort of bonding and a base carrier. http://www.businessinsider.com/lightpaper-technology-prints-... With the thickness of the material thin as paper there is very limited optical scattering possible, which would require enormous amount of LEDs to compensate for. To me something does not add up here or it is truly a revolutionary technology, but I do know from our optical simulations ink printing alone won’t make that possible.

Thank you for writing this. I think the skepticism of HN is what keeps me coming back. My (more or less) ignorant perspective on so many topics is offset by comments like these, which without, I'd have nothing to temper the marketing material within the links themselves.

Agreed. Although LEDs are far more efficient than incandescent bulbs, they still produce a non-trivial amount of heat. Almost all useful LEDs have some form of heat sink (for a flashlight, it can be a substantial block of aluminum, for a through-hole LED, it is the leads). Without some sort of a solid, heat-distributing backing, I cannot figure out what they would do with the heat produced by these.

As an example, I have a big-ass LED flashlight (google trustfire tr-j20). It gets extremely hot to the touch, and it has a massive heat sink.

My guess is they've simply using the backlights of LCD panels: https://www.youtube.com/watch?v=jiejNAUwcQ8#t=34

They can scatter light and are deceptively thin. Coupling with (maybe) some fibre cables and you've pretty much got what they're offering. I'd doubt they're actually offering a unique product that illuminates the product as advertised.

LCD panels don't have a paper thin backlight, they are lit from the sides of the display and the light is refracted and diffused trough a thin layer of plastic, this is why all LCD's have light bleed to some degree since the diffusion is not uniform throughout the surface of the display. This technology seems to be completely different and the LED's are infused evenly throughout the material rather than being simply located at the edges. The diodes they use also seem to be very different than commercially available LED's both in terms of their size(several orders of magnitude smaller) and resisting/allowing deformation without functional issues. As it's currently shown this technology is much more similar to OLED and other internally illuminating displays rather than to LCD's, or traditional LED array displays.

The shot of the Audi logo matching the brightness of the LED DTRs made me pause. I'm not holding my breath, but I do hope they can deliver. If it's as good as they claim, it actually could change the way we do lighting.

Maybe it's an AMOLED-like tech with pre-configured drivers? e.g. instead of software driving the display, when the switch is flipped to on the entire surface goes ALL ON

I'm always suspicious of LED room lights when they don't state the price upfront. They've been pretty price in the past, but the cost is dropping quickly. Some quick Googling found http://www.environmentallights.com/led-light-panels/ultra-th... which has 24" x 24" 17W panel for $250. That panel outputs 3000 lux == 3k lumens / sq meter = 1.1k lumens for 4 sq ft. This is the same as a 75W incandescent bulb. A standard 13W LED bulb is $16 for the same amount of light.

So the price needs to drop by about 1-2 orders of magnitude before these become practical for most people.

OLED Lighting is LED 2.0. LG [1] is already pushing this into production.

[1] https://www.youtube.com/watch?v=aeoJEog1XYE

For a glowing-surface product you can get right now, check out electroluminescent paint.



Aha! this looks promising, I've been looking for something similar for a while. I want to make this http://www.secretbatcave.co.uk/electronics/tron-case/ much neater.

At the moment its held on with tape, and its not long lasting.

Why are they talking about this and not taking over the backlight market for LCD displays? That market wants flat light sources right now and will pay for them. Because, maybe, this doesn't really work?

and why not show off Tron suits? Considering the price of light tapes this might be appealing if its cheap enough to fiddle with.

I would like to see it on clothing, particularly bicycle and motorcycle gear. Might be awesome for safety persons too (first responders)

I guess that's one of the applications the two inventors have in mind (outdoor clothing).

Came across their early announcement beginning of this year (http://www.cdapress.com/news/local_news/article_6c1e49d6-8f2...) - now it seems they are getting ready to deliver / having every day use applications on the market in the next 6 months (by 3rd party industry members).

There's something to be said in favor of light emitted from a point, like an HID bulb, or along a line like an incandescent light bulb. The advantages of points and lines is ease of constructing lenses and optics to put the light where you want. This is a problem for LEDs where the light is emitted on a plane, or multiple parallel lines, or space-filling curves depending on the semiconductor process used. What would be some advantages of a planar light like these, if they existed?

Light from large sources is "softer", meaning the shadows are not as harsh. This is why you see photographers use soft boxes or umbrellas, or videographers using light panels.

Indoor lighting is usually more appealing, and more functional, from a large source, as well.

Imagine being in a dark room with only one, small light source, and trying to do some sort of fine motor work. If the room is evenly lit, from a large source, it's easy to see what you're doing. But if there's just one small source, you end up casting a shadow on what you're trying to work on, making it much more difficult.

Constant diffuse / ambient lighting without shadows. Kinda like a lightbox.

Would be nice for working on my computer. It's really tough to light the Inside of a PC case without creating shadows everywhere. The same thing goes for working on a car engine. these applied to the underside of a hood would be very nice.

Beyond actual lighting applications, this has really cool possibilities for cheap displays on pretty much anything. Or cool logos or safety clothing.

Could do some cool stuff with a coffee cup that could generate the electricity from the thermoelectric effect[1] to light up and display the temperature of the coffee. There are better ways to do this I suppose but this is just an example.


Fascinating piece of tech if they actually manage to deliver on it. It'd be amazing if there was some more information on it though, the only stuff I can find is them explaining that it's LEDs mixed with ink between two conductive layers and an additional protective layer. Then a lot of fancy mockups that don't tell me anything about the tech they're selling.

Even if this vastly underdelivers, it might do away with the inverters needed for el-wire/panels which would be neat.

Their technology is an assembly and packaging technology which has no bearing on driver electronics (inverters and whatever else).

The hard part about this (beyond many, many devilish details) is the deposition of an insulator separating the top and bottom conductors, which has to be the right thickness on a micron scale, and not interfere with conductivity of the electrodes. A very big devil, indeed.

It may work, but it is not easy. Also, the LEDs have to be specifically fabricated for their technique; they cannot use feedstock from the existing industry.

> It'd be amazing if there was some more information on it though

I suspect that there is little information on it, either because they are not entirely solid on the information themsilves, or that they do not want to risk letting others make similar products before they have a chance to hit market, or some combination of the two.

I hope it is the latter, as that would mean it is a lot more likely this will ever come to market.

Yeah, a video of it in action would be incredible though. The single picture of it isn't quite convincing yet. Reading through articles on it it appears they're on the first iteration of the design though, which appearently suffers from problems with uniform lighting they're hoping to resolve in the comming months, so that might be the reason they're not showing any more proof of their claims.

This will be really cool when it's a real thing. Right now it seems to be limited to very small scale samples and Photoshopped mockups.

This is one of three HN links on the front page that uses this new fad where the landing consists of nothing but a full screen image, no content and a less than obvious notification that you should scroll down to see something actually useful. Stahp.

One thing I've disliked about the current crop of thin, high-PPI LCD screens is the unavoidable unevenness in backlighting caused by their thin, hard-to-make-optically-perfect diffusers. Even the Retina Display on the MacBook Pro isn't immune from it.

Though Rohinni doesn't visualize it in their applications section, Lightpaper looks like it could enable diffuser-less, razor-thin LCD displays with potentially far greater luminance uniformity than current backlight solutions.

These would be much worse. They're essentially an array of tiny LEDs and a consequence of the distribution of LED forward voltages will mean that some of the LEDs are going to hog current and others will get less. This will lead to bright spots, and the human eye is actually very sensitive to this. You get the same problem with OLED displays and people have complained a lot about the visible noise on OLED phones like the Samsung Galaxy Nexus.

Usually what you do to solve that problem is chain a bunch of LEDs together in series and then those groups together in parallel. If your process technology is +- 5% then chaining 5 LEDs in a row will even out your average error to +-1% instead. Which makes a big difference. Of course, if they don't do that then you're right that there can be problems.

Hello my name is Alexander and I am the founder of a French information site for 3D printing. It happens that I wrote an article on "lightpaper" ( http://www.priximprimante3d.com/led/ ) and wanted to know if the process used to manufacture this device is similar to that used to manufacture OLED.

Given that an LED can act "in reverse", as photovoltaic source, what would be the efficiency of this as a solar cell? Any ideas?

Short answer: no. I just wrote a long diatribe attempting to explain why using my very limited knowledge of semiconductor physics, but realized I couldn't do so without making some substantial guesses.

So instead, I'll offer some (probably fallacious, but likely still correct in its conclusion) logical deduction -- If this was likely to be a good photovoltaic source, the inverse would also likely be true. That is, that good photovoltaic sources would emit heaps of light when a current was applied.

In short, LEDs are semi conductors optimized to have a very specific direct energy band gap which produces photons in the visible light spectrum. This causes the semiconductor to shed excess electrons as visible light energy.

Photodiodes (used for PV arrays) are similar, but optimized for a completely different goal. They attempt to maximize the size of their depletion region. I don't know that the energy band gap is as important, though I'd imagine the narrower the better. Either way, this is done to maximize the likelihood that an incident photon will excite one of the molecules in that region of the diode, thereby freeing up an electron and causing it to flow around the circuit.

We just replied with very similar responses!

FYI solar cells would not make good light sources since the most common ones (silicon based) are indirect band gap. For LEDs (and lasers) a direct band gap material is required.

You are correct about the depletion region needing to be large for solar cells, but narrower is not necessarily better. This is because if you make the band gap super narrow (say 0.5eV) and most of your energy comes in as much higher energy photons (1eV+) you are discarding all of the energy besides that 0.5eV from those photons. The band gap is tuned to get the highest responsivity at wavelengths where the most energy is coming in if it is tuned at all.

So in the case of a narrow band gap, where does the excess energy go? I'd guess it must be shed as a lower energy photon?

Nope! In very rare cases it can generate multiple electron hole pairs the photon if it has enough energy to do that. Almost all of the time however it will generate a phonon (aka heat) rather than a photon with the extra energy. A phonon is a wave in matter rather than electromagnetism (photon).

Also, most white LEDs are really blue, or sometimes UV, LEDs driving a fluorescent phosphor. That won't work in reverse.

Very, very low. I won't go into too much detail here, but LEDs and solar PN junctions (aka diodes) have very different designs.

The two big things I will mention are that LEDs are made with direct band gap semiconductors whereas efficient solar cells are made with indirect bandgap semiconductors.

The other issue is that solar cells rely on as big of a depletion region as possible to collect light whereas in LEDs the depletion region is considerably smaller.

This paper (2012) shows that it is possible to create LEDs by printing zinc oxide and a conducting polymer on paper: http://liu.diva-portal.org/smash/get/diva2:515790/FULLTEXT01

Maybe it's derived from this technique?

Trying to find it, but does anyone know the battery life of it? Or does it have to have a constant source of power?

It's not powered internally. You apply it to a surface and power it like you would a normal LED.

Makes sense now, thank you!

The tech claims to be using microscopic light-emitting diodes, which need a constant source of power.

Ahh, thank you!

That photo of the team is hilarious.As if the men wore masks to wind up the woman.

I'd be a lot more interested in this if the photos of their office showed their product actually being used in the spaces.

Anyone have an idea as to the lumens per sqft?

Since they aren't saying, it's doubtful they do better than current OLED panels, which framkly are pitifully dim.

How do those compare to a standard drop-ceiling Fluorescent fixture?

Where can I buy a sample of this?

From the FastCo link [1] in another comment:

"Consumers should start to see Lightpaper in the wild around the middle of 2015. But Rohinni won't be aiming at the home hobbyist market until after it takes hold in the commercial and industrial space."


1: http://www.fastcolabs.com/3038890/rohinnis-lightpaper-is-inc...

I bought a sample light-emitting capacitor from CeeLite a few years ago. I was thinking of incorporating LECs into a building project but the very faint buzzing noise from the LEC and the understanding that light emissions would degrade over time was enough that I went with conventional light fixtures instead. This Lightpaper article remind me of that. I'm a little skeptical, but again, if they would just make samples available...

An unenlightened plan, for a category like this where it's not immediately obvious what can be done with your product.

It's a typical plan when your initial product cost is going to be way high. Commercial/industrial users will pay high prices if the application is what they want. Home users will not.

You might be surprised.

They are local to me...maybe I will swing in.

I would love those wall-decals for my room. Beautiful

You can always buy and cut up electroluminescent panels, like this:


Agreed, i was just about to say the same thing with this vid: https://www.youtube.com/watch?v=qkA0YdNEsqU

This is called LitCoat and more information is on litcoat.com LitCoat is nano coating and consist of spray paint layers working together:

(1) Conductive - (2) Dielectric - (3) EL (Electroluminescent) - (4) Conductive layer and then you seal it off with the (5) Top layer. (Once applied save to touch)

From principle it can be applied on everything but it is depending on the under-layer trace thickness and uniformity. In case of irregularity of the surface it would require treatment for a more homogeneous surface.

DIY: http://www.litcoat.com/product/litcoat-electroluminescent-pa...

> This is called LitCoat and more information is on litcoat.com LitCoat is nano coating and consist of spray paint layers working together:

Is your claim that the Rohinni Light Paper is actually based on the technology that LitCoat is pushing?

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