Finding a Display You Can Read in the Sun?

max3000 asks: "I'm currently building an embedded device that will be used outdoors, and the technology is pretty much nailed down at this point, except the display. Quite honestly, I'm confused and lost in all the display technologies out there: LCD (TFT, passive/active, and so forth), ChLCD, OLED, FED, AMLCD, EL, electrophoretic, ePaper like eInk, and more (some of which may overlap). Can you help a confused, fellow reader? What I need is (apparently) fairly complicated: an outdoor, sunlight-readable (at-a-glance readable, not squint-your-eyes readable), VGA/SVGA display. The display should have a 4-6 inch diagonal, capable of displaying at least 16 color grayscale, and it should be based on a technology with a roadmap to color in 2-3 years time. If not driveable directly from a PC, the display should come with a development kit that is." What small displays are out there that can meet these specifications?

Comments

Ask Sharp

[Ant P.]

They made the Game Boy Advance LCD.

Re:Ask Sharp

[fbjon]

The GBA (SP) had a transflective TFT, and was perfectly readable in the brightest sunlight, but only when tilted towards the sun. Tilt it so the screen is in shadow, and you can't see anything, because the front-light is way too weak to compete with daytime ambient light. That's the real problem: either you turn your screen towards the sun all the time, or you put in a powerful enough light that can rival the ambient lighting, and speedily drain the batteries at the same time.

Re:Have you looked?

[orclevegam]

I think that was his problem, he looked and got overwhelmed. There really is a large number of competing display technologies out right now, and without having display samples to look at I can understand his confusion. I'm not sure about the color option, or development kit, but if you're looking for something that dosn't need to be viewable in the dark e-Ink is very promising. Only major problem with e-Ink is the refresh rate is pathetic, so not really viable for any sort of video. Other than that, OLED is the hot new thing, but those are still hard to come by in larger display sizes, and even then pricey unless you're looking to buy in bulk and have some clout to throw around. Also coming over the horizon be looking for SED displays.

Gas stations

[Anonymous Coward]

"What small displays are out there that can meet these specifications?"

Simple. LCD with a backlight that turns off and on. Look at what gas station pumps use.

Re:Have you looked?

[QuantumG]

heh, buying a few bananas and heading off to ask the monkeys at the zoo would be more productive than asking Slashdot.

OLPC

[Anonymous Coward]

you might want to look at the OLPC http://laptop.org/

        * Liquid-crystal display: 7.5" Dual-mode TFT display
        * Viewing area: 152.4 mm × 114.3 mm
        * Resolution: 1200 (H) × 900 (V) resolution (200 DPI)
        * Mono display: High-resolution, reflective monochrome mode
        * Color display: Standard-resolution, quincunx-sampled, transmissive color mode
        * Special "DCON" chip, that enables deswizzling and anti-aliasing in color mode, while enabling the display to remain live with the processor suspended.

http://laptop.org/en/laptop/hardware/specs.shtml

Re:Have you looked?

[djbckr]

Look into Aircraft Avionics Displays - contact some of those manufacturers (there are quite a few).

Evident in the Palm and phones

[jbarr]

"Back in the day" my Pilot 1000, Palm iii, and Palm Vx PDA's all had monochrome, backlit displays that were very viewable in the dark, in normal office lighting, and in bright sunlight. No, they weren't color, but I NEVER had to worry about being able to read the screens. Now, over a decade later we have PDA's that rival small laptops, have amazing storage capacities, execute applications unheard of in the past,but are COMPLETELY USELESS in bright sunlight. Despite all of the advances, I sometimes long for the days of simpler designs. I would personally love to see the Palm Vx resurrected with some of today's features but a high resolution monochrome screen.

And the same holds true for cell phones. I have a typical LG phone from Verizon (provided by work, do I have no choice in the model) and it has a great battery life, the features are decent, and the voice quality is better than most, but in the sinlight, the internal screen is completely unusable. The monochrome external screen is amazingly clear in sunlight, but it is useless in that it doesn't match the internal screen. Thank, God for speed dials.

OLPC's XO

[Adhemar]

I googled in my memory.

At last FOSDEM, Jim Gettys gave a presentation of the technical specs of OLPC's XO-1 machine. I remember I found the part about the low-voltage sunlight readable display particularly impressive for a $135 device.

OLPC XO-1 manifacturer Quanta announced selling a XO-like device on the open market later this year, at a price around $200. Presumably it will have a display of the same technology.

Priorities!

[dour power]

I'm pretty sure you would have other things to worry about if you were in the sun.

Transreflective LCD

[stlthVector]

Look for a Trans-reflective LCD. These don't wash out in the sun light. I'm pretty sure all LCD's are active matrix now so you shouldn't need to worry about that.

Re:eInk

[Anonymous Coward]

Actually they Sony reader only does 2-bit grayscale, he wants 4-bit.

But otherwise, yeah it meets his requirements.

Solarism

[Xerotope]

We work outdoors a lot with our robots, and we found the best solution to be monitors made by Solarism. They're kinda pricey, but they put out nearly four times the brightness of a standard LCD.

Cannot do

[thsths]

I think the main problem is that you want both colour and readability in direct sunlight. While transflective displays work very well in bright light, they do not usually come in colour (of if they do, they are very dark). Colour displays usually need a back light, and it is very likely that it cannot compete with direct sunlight.

The math is simple: direct sun light is about 1000 watts per square meter, or 13 watts on your display size. The back light has to be stronger, say twice as bright, but you loose about 50% of the light in the light bulb, in the light distribution, in the polariser and again in the colour filter. So you would need 400 watt of electrical energy to drive the back light!

Short version of the story: colour, good contrast and direct sunlight don't mix. Maybe some day with e-ink, but not right now.

Re:Cannot do

[cpaglee]

Gosh your math is wrong. The 1000 watts of light per square meter is based on the amount of light from a 1000 watt incandescent light bulb. The light from a CCFL fluorescent light bulb would use MUCH less energy. Of course it is possible! See the comments above.

300?

[vertinox]

Emissary: The thousand nations of the Slashdot Empire descend upon you! Our moderation points will blot out the sun!
Stelios: [grins] Then we will post comments in the shade.

Re:eInk

[geekboy642]

There's a store nearby that has one of those on a demo stand. I wouldn't use that particular type of screen, the refresh rate is abysmal. Switching between pages has a noticeable and aggravating delay.

ePaper

[Meneth]

I recommend e-paper. The device I've tried, the iRex iLiad, works in all well-lit environments. It even runs Linux.

Simple: Transreflective

[evilviper]

The only existing screen technology that likely suits your needs is transreflective LCDs. They're widely available, so you shouldn't have an problems.

Display tech with potential, like e-Ink, just isn't there yet, and likely won't be for several years.

Of course, if you want to go crazy, you could always grab an old LCD, and mount it in an enclosure with a massively powerful backlight, and lots of airflow directed at the screen to keep the LCD from burning up.