Forget LCDs and LEDs, Here Come LPDs

waderoush writes "It's not every day you hear about a brand new display technology, but San Jose, CA-based Prysm came out of stealth mode yesterday to talk about its plans for manufacturing laser phosphor displays, or LPDs. The new devices, which the company will show off at the Integrated Systems Europe trade show in Amsterdam next month, reportedly use 25 percent as much electricity as equivalently-sized LCD screens. And they should be easier to manufacture too, since they don't have a backplane of transistors like LCD screens: the image is generated by a laser beam that sweeps across phosphor stripes under the control of a scanning mirror. The venture-funded startup, which plans to build and sell LPD screens under its own brand, is promoting them as a low-cost, low-maintenance way to display information in lobbies, airports, broadcast studios, command centers, and the like."

Comments

How Thick is the Display?

[eldavojohn]

And they should be easier to manufacture too, since they don't have a backplane of transistors like LCD screens: the image is generated by a laser beam that sweeps across phosphor stripes under the control of a scanning mirror.

Of all the information I can find, no one is addressing the thickness of the display unit. I'm not saying it can't be done in close quarters but I'm basically inquiring how thick the unit must be in order for a laser beam to sweep across the phospher stripes that comprise the screen? Are we talking about moving back towards the sizes of back projector displays? Because it might not matter how efficient or awesome the picture display is to the consumer.

I guess that might explain why they're targeting airports and malls and not your living room.

I believe this particular patent image illustrates what I'm wondering about (Roger Hajjar is one of Prysm's founders).

CA-based Prysm came out of stealth mode yesterday

No one can fly under the radar when they need to patent their invention:
Laser displays using UV-excitable phosphors emitting visible colored light
Laser vector scanner systems with display screens having optical fluorescent materials
Optical designs for scanning beam display systems using fluorescent screens
Phosphor Compositions For Scanning Beam Displays

Prysm's founders (Amit Jain and Roger Hajjar) have had their names on quite a few display related patents since 2005. I'm excited a small startup can enter this market but I'm skeptical of the marketability due to the one drawback: a step backwards in compactness and style.

Re:How Thick is the Display?

[Zediker]

They shouldnt be any worse than the existing DLP displays which are quite thin since they both utilize similar technology: scanning micro mirrors.

Re:How Thick is the Display?

[mea37]

At the end of TFA, they claim that conceptually it would work for a laptop display; so it must be pretty thin. The reason to target big displays before worrying about home TV's seems to be that the cost of manufacture is less an issue there. Until they can do relatively cheap mass-production, they won't be able to address the TV market.

Also, the headline notwithstanding, this may face tough competition in the TV market from advances in LED-type displays.

Re:How Thick is the Display?

[natehoy]

Yeah, but cost is also a factor in a lot of cases, and this could well be an acceptable compromise for a lot of people.

These are supposedly a lot cheaper to manufacture and draw a lot less power, so if you are willing to put up with something that has some depth, you may be able to skip the 55 inch screen and go straight to 70 inches for the same money, and lower long-term costs of operation. Or get that 55-inch screen and have $800 left to buy a whole lot of movies to play on it.

A lot of people still have CRT or back-projection televisions. Something like this could appeal to those people, because they are already used to their TV having some depth anyway, and you can get them to high def in an affordable way. I have to imagine a laser projection could at least be slimmer than a CRT.

Plus, CRTs are HEAVY in addition to being bulky. It sounds like something like this would be a box filled with mostly air, so it's at least easier to move around.

Actually, if you made 4 lasers (or 1 laser with a very clever series of 4 mirrors), each one could be responsible for 1/4 of the screen and you'd end up with something shallower than a 1-laser rig. 16 lasers or mirrors would make it shallower still. But then you're starting to draw as much power as an LCD and manufacturing costs are probably as high or higher. So there are adaptations to this technology that could make them slimmer, if you're willing to pay for them, and if you don't apply them to the point you are exceeding the cost of LCD.

Re:How Thick is the Display?

[stevew]

Well - I designed what would be portion 320 in the diagram, the image modulation system for a scanning LED TV. The first problem was that LEDs were too dim at the time. The lasers in this system against a phosphor take care of that issue. The second issue you have is what is called the pin-cushion effect. As you scan the laser over the surface of the rotating polygon, it will tend to modulate the length of the scanline making the picture look like a pin cushion. I had a way to fix this in the modulation controller - can't talk about HOW to fix it ;-) Just know that is a pretty big problem to overcome.

Once you have a method to overcome the pin-cushion effect, then you need to have to have a way to align the TVs in production (another REAL headache I didn't come up with a solution for..but then we only got to the prototype stage so didn't have to face that issue.)

Finally - there is the issue of NOISE. Rotating mirrors can be REALLY loud. Our prototype sounded like a jet engine when we spooled up the motors. The precision optics are also expensive. The mechanical engineers believed they could build a much quieter mirror assembly - maybe with air bearings.

So there are a lot of real - practical - tough design problems with this approach.

Finally - I expect it to be a relatively BIG TV.

It's a neat technology - but I don't believe there is any market for it.

Re:How Thick is the Display?

[Lord Lode]

Would you draw more power with 16 lasers? Each laser needs to cover only 1/16th of the area so theoretically also 1/16th of the power (for the same overall brightness).

Re:How Thick is the Display?

[jcr]

It has to be far enough back to reach all edges.

No, it just has to have some mirror arrangement that allows it to reach the whole screen. I don't see any reason why the laser has to strike the phosphor at anything close to a perpendicular alignment.

-jcr

Re:How Thick is the Display?

[cool_story_bro]

I don't see any reason why the laser has to strike the phosphor at anything close to a perpendicular alignment.

The angle at which the beam strikes the phosphor would determine the shape of the intersecting region, which may be difficult to correct for. However, a small mirror near each "pixel" that redirected the beam straight at the phosphor would likely correct the situation without taking up too much extra space.

Re:How Thick is the Display?

[mea37]

Interesting assertions.

DLP sets use moving components, often including a rotating "color wheel". I've never heard of an audible "whir" being a problem there, so I'll hold off on speculating whether there would be one here.

I also know of no reason the screen couldn't be as thin as a notebook LED. I would think the laser's beam thickness would be the limiting factor (since it would govern how shallow an angle the beam could use to approach the screen without spilling across pixels).

Re:How Thick is the Display?

[Pinky's Brain]

Precision optics seem like overkill to me ... all that shit with f-theta lenses and optical correction of pin-cushions seems so ... archaic.

As long as the distortion is static and a sufficient maximum distance between lines is maintained you can just correct it digitally can't you? Transistors are cheap nowadays, really really cheap, hardware to perform an image warp on a HD signal is pennies worth of die space on an ASIC (in volume, the million dollar mask costs have to be earned back first of course).

Re:How Thick is the Display?

[omnichad]

Well, getting rid of the lead faraday cage on the front and using thinner glass would make them quite a bit more portable.

Re:How Thick is the Display?

[cyberbrian]

According to: http://www.prysm.com/about_lpd.html
The technique uses an array of solid state laser diodes.

So...it sounds like the system will not require a large depth, since there is not a single laser trying to excite all phosphors on the display.

Re:How Thick is the Display?

[Angst Badger]

"Ordinary" light in this case is incoherent light, i.e., light in which the individual waves are not synchronized with each other, either by being out of phase or being of different wavelengths, usually both. This is the kind of light that comes from most light sources. Laser light is coherent: it's (mostly) all one wavelength and the peaks and troughs of the waves are all synchronized.

Re:How Thick is the Display?

[wiredlogic]

The back surface of the image plane doesn't have to be flat. There could be ridges molded in place to reflect/refract the laser into the phosphors.

Re:How Thick is the Display?

[Carnildo]

You can't steer an electron beam with a mirror. You need magnets, and those can't generate sharp turns.

Argh

[Angst Badger]

I had a similar idea, only instead of a scanning mirror, I was going to use chunks of neutronium to bend the light beams. I've had a little trouble sourcing the materials, though...

do not want

[drinkypoo]

guaranteed to be thicker than LED or LCD, and with phosphor delay; I want LED so that I can have [effectively] instant transitions. we can get back the delay effect with processing, but you can't eliminate phosphor delays when you've got phosphors.

Re:do not want

[Abcd1234]

WTF... there was a time when people didn't want to move to LCD because of motion blur issues, problems that CRTs, a phosphor-based technology, didn't have. Now you're saying the exact opposite is the case? *boggle*

Re:do not want

[pz]

guaranteed to be thicker than LED or LCD, and with phosphor delay; I want LED so that I can have [effectively] instant transitions. we can get back the delay effect with processing, but you can't eliminate phosphor delays when you've got phosphors.

There is essentially zero phosphor delay (I defy you to measure it ... I am a visual neuroscientist and have, so yes, it is possible, and no, it is not easy) on the scale of perceptual latencies. I believe the latency from excitation to phosphor emission is on the nanosecond scale. The typical perceptual delays in the early visual system (retina and the first few stages of processing in the brain) are on order of 30 milliseconds, going from the time photons enter the eye to the first wave of activity in primary visual cortex. Different orders of magnitude. Like 6. Phosphor delay is irrelevant.

What you are perhaps thinking of is the phosphor DECAY which is another thing entirely. When phosphors are excited (such as by an impinging electron or photon beam) the emitted brightness steps up almost instantaneously and then decays down through an exponential relaxation curve. That decay time can tend to blur images when too long, or induce eye bleed (to use the vernacular) when the update rate is too low. The thing is that phosphor decays can be adjusted by reformulating the compounds, and are determined ultimately at time of manufacturing. Very fast phosphors are available to support KHz updates, but also very slow ones (some older oscilloscopes have phosphor decay constants measured in seconds).

Contemporary LCD monitors have typically 2 or 3 frames of latency because of the push to get faster transition times. Those 5 ms response time LCDs get fast specs by overdriving the pixels in a highly controlled fashion, but one that requires knowing what is on the next handful of frames. Since we live in a causal world, that means introducing a 2-3 frame latency for processing within the display. Since the update rates on LCDs are typically 60 Hz, that's on order of 45 ms latency, a non-trivial fraction of the loop from visual perception to motor action (known in the gaming vernacular as twitch response). If you're watching a movie, that latency is irrelevant and wholly, entirely unperceived. If you're playing a game, then it is very important.

thickness

[Anonymous Coward]

Probably wont get much thinner than 5"-6" but some of us don't care much about depth. All else being equal, if it's price is lower and it uses 1/4 the electricity, I'm interested.

Similar idea

[Walterk]

I had a similar idea once, except using electrons instead of lasers. It also required a vacuum tube for the electrons to travel through. I called it the Fluorescent Electron Cathode Konduit, or FECK for short. After considering it a while, I thought the concept was rather ludicrious and without merit, so abandoned it.

"Command centers"

[ewg]

About time! I'm sick of the lackluster displays in my command center.

phosphor burn?

[AmericanGladiator]

I didn't see any mention in the article - will it have this horrible weakness that CRTs had?

Re:phosphor burn?

[Anonymous Coward]

Phosphor burn is massively overstated. I'm still using the same 19" Hitachi I got in 1997 as my regular computer monitor and there's zero evidence of phosphor burn. It's also still bright enough to use under bright fluorescent lighting (and more than bright enough to use in a dungeon environment).

Mitsubishi LaserVue

[ArhcAngel]

How is this better than Mitsubishi's LaserVue technology? It's basically a laser DLP to phosphor opposed to whatever material is used by Mitsubishi for a standard DLP screen. It even looks like the LaserVue uses less power than this.

Ouch

[idiotnot]

Lasers+moving mirror == great reliability! Have a feeling these are going to make DLP or LCD lamp replacement look downright economical. Still prefer Plasma, personally, but the LED/LCD my SO's dad bought isn't horrible. Even at 240Hz, I did still notice some streaking, though (watching a football game).

dont look at TV

[ionix5891]

with remaining eye

Similar to LaserVue?

[RingDev]

If it is similar to Mitshibishi's LaserVue http://www.mitsubishi-tv.com/product/L65A90 a 65" display would be around 10" deep.

-Rick

Re:Hmm

[girlintraining]

"Do not break screen and stare into laser"?

"I can't let you do that, Dave."

The screen is not... it's not

[Arancaytar]

Something you can just refresh all at once. It's not a big lump of transistors.

It's a series of cathode ray tubes!

Vaguely familiar

[C9OE-6015-B8]

This is not far removed from the Scophony projection system of the 1930's.

Re:LPD screen or LPD screen?

[girlintraining]

If it is new, it is unfortunate not only to reuse an acronym, but reusing one in the same domain.

There are only 17,576 three letter acronyms. We've been warning people for years of the need to upgrade to TLAv6, which allows for a wider range of three letter acronyms, including punctuation and numbers as well as unicode support. But many major buzzword providers have refused to upgrade. The last unique TLAs will be depleted within 18 months in our field. Thanks to AAT (Acronym Address Translation), there are already far more TLAs than there are available spaces -- we've been using CIAR (Classless Inter-Acronym Routing) to separate namespaces based on subject matter and field, but it's only a matter of time before even that fails.

Forget LAPD, I'm waiting for FEDs

[Max(10)]

FEDs (Field emission displays) are superior to CRTs, LCDs and these new LPDs in every way. FEDs have the same thin 2-4 mm profile as LCDs, but unlike LCDs produce very bright and clear images even in direct sunlight (which is why they were used as HUDs in airplanes) while consuming up to 10 times less power. Sony had a 36" FED prototype that consumed only 14 W, which is 1/8 of what a typical LCD and 1/2 of what an LPD of that size would consume.

Re:LPD screen or LPD screen?

[pjt33]

A gentleman? I think you missed a minor detail there...