Mitsubishi's Red Laser Diode Advacement Could Lead To Brighter Pico Projectors - HotHardware
Mitsubishi's Red Laser Diode Advacement Could Lead To Brighter Pico Projectors

Mitsubishi's Red Laser Diode Advacement Could Lead To Brighter Pico Projectors

The first wave of pico projectors had all sorts of steam behind it, but that enthusiasm was soon pushed away as newer and more wide-ranging products came to market. After a year-long lull, it really feels like the mini projector has its groove back, and now we're hearing more and more about new options and new progress being made in order to make them more suitable for the mainstream market.

Mitsubishi Electric has today announced something that's highly technical in nature, but could have a significant impact on the future production of these devices. The company's new 638-nanometer (nm) wavelength red laser diode (ML520G72) offers the world’s highest output power in 638 nm band LDs, making it ideal for pico projectors and other portable display systems that require a red light source with high brightness. In case you're unfamiliar, red is a pretty important part of the projection equation, and much like the improvements on blue in the OLED world, this here could really shake things up going forward.



In comparison with LEDs, laser diodes deliver higher output power with less power consumption, enabling batteries to last longer; in July of last year, the company launched a 638nm LD that offers 300 milliwatts (mW) output power, high brightness and pure red tone. The new version, however, offers an even higher output power of 500 mW, currently the world’s highest in 638 nm band, which helps achieve high-luminous projectors of up to 60 lumen. That's the kicker. Currently, the nicest pico projector out hits a peak at 50 lumens, which essentially tells you how bright the image can be projected in a well lit room. The higher the lumens, the less dark  your cave has to be in order to get a solid image on the wall or projection screen. One of the main complaints with these devices is that they don't shine bright in rooms with ambient light, but this innovation could definitely help change that.  In addition, the new LD has an industry-leading electrical conversion ratio of 32% at 500 mW, and at a case temperature of 25 degrees C, which help to reduce power consumption in pico projectors.

Samples are expected to start shipping next month, though there's no telling when this will begin to affect shipping pico projectors. We're guessing it won't be long before the little guys are as bright as the big guys, though.
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So how long to you think before we see laser Diodes in LCDs? :-P

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The next advancement in monitors/TVs is going to be OLED display, but the cost is too expensive to be practical at this point.

For comparison: 60-watt incandescent and18-watt fluorescent bulbs give off about 1000 lumens. I'm guessing lumens work differently in the projector world.

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This is mostly irrelevant to the brightness of LD projectors. The most difficult of the three colors (red, green, blue) to increase the brightness of is blue. Increasing the red brightness without increasing the blue buys you nothing, unless you want to watch a video with everything tinted red.

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Thanks for the explanation. I would have assumed all would be equally important but I guess I'd be wrong.

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gibbersome:

All three colors ARE equally important. To make white light, you need approximately equal intensities from each of the primary colors.

The issue is that they are NOT equally difficult to make laser diodes with. Blue laser diodes are much more difficult than red laser diodes. The first room-temperature visible red laser diode was invented about 30 years earlier than the first blue. And the blue LDs are still lower in power than red.

In other words, blue is the bottleneck to improving the brightness of 3-color laser-diode projectors.

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Ahhh, I see what you mean now! Got it! Blue LD tech is just behind for the other colors. This sounds pretty fascinating, I wonder why blue was the hardest of the three.

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gibbersome:

The bulbs you are thinking of emit light in all directions (technically, nearly 4 Pi steradians). A projector emits light in a highly-directional manner.

However, 60 lumens is quite low as compared to full size projectors. A typical 1080p home-theater projector emits around 300 - 1500 lumens (depending on whether you operate it in a color-accurate cinema mode or an uncalibrated high-brightness mode). But home theater projectors typically project onto screens in the 80 - 120 inch (diagonal) range.

I'd estimate the projected image in the attached photograph to have a diagonal size of about 40 inches. The amount of light (lumens) required for a given brightness is proportional to the area. So if the diagonal is 3 times less, the area is 9 times less. So, a 1500 lumen image projected to a 120 inch screen would be as bright as a 170 lumen image projected to a 40 inch size.

So 60 lumens at 40 inches would probably look washed-out in a well-lit room, but it would probably be acceptable in a dimly lit room.

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Really appreciate the additional explanation. I was thinking along the same lines that LD light is very directional.

So the jump from 50 lumens to 60 lumens, while significant, still falls short of what the mainstream user would consider acceptable.

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1) Would the wiimotes actually work with the sensor bar that far below where the players would be pointing?

2) Have you ever seen such a diverse group of plain shirt wearing guys who love guitars and dogs, with no bong in the room?

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Hmmm...good point. The dog looks a little out of it.

Of course they forget to mention that using a pico projector for playing the Wii would be a bad idea, especially considering you could very easily step in front of the picture.

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rofl 3vi1 20 years back this conversation is getting pretty deep. I think we need to drop the dog off at the emergency room he's turning green.

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The recent commercial with the pico projector attached to a cell phone would make this type of use very relevant. Although I would thing packaging it as one thing and or as a blue tooth or other wirelessly connected device would be a better implementation. I wonder when we will see holographic display technology?

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