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Displays

Finding a Display You Can Read in the Sun? 63

Posted by Cliff
from the an-spf-100-glare-screen dept.
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?
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Finding a Display You Can Read in the Sun?

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  • Ask Sharp (Score:4, Informative)

    by Ant P. (974313) on Saturday April 14, 2007 @08:23AM (#18730387) Homepage
    They made the Game Boy Advance LCD.
    • Re:Ask Sharp (Score:4, Informative)

      by fbjon (692006) on Saturday April 14, 2007 @08:36AM (#18730467) Homepage Journal
      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.
      • by timeOday (582209)
        Transflective TFT is what handheld GPS use, too, and with exactly the result you describe - direct sunlight = good, darkness = good (using the backlight), bright ambient sunlight and especially glare = bad.
    • He asked for a display you COULD read in sunlight, not that you HAVE to read in sunlight. Seriously, have you ever tried to use one of those? [penny-arcade.com]
      • by Ant P. (974313)
        The newer GBAs have a different screen that's nowhere near as bad as the original. If that doesn't help, there's also a contrast control hidden under the back label.
    • by Trogre (513942)
      Sharp's reflective LCD screens work beautifully on their Zaurus models too. I can read the screen of my lovely SL-5600 in the sun with no problems (so long as I tilt it at the right angle :) .
  • Gas stations (Score:2, Informative)

    by 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.
  • OLPC (Score:4, Informative)

    by Anonymous Coward on Saturday April 14, 2007 @08:38AM (#18730487)
    you might want to look at the OLPC http://laptop.org/ [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 [laptop.org]

  • eInk (Score:2, Offtopic)

    by TheSHAD0W (258774)
    The Sony Reader [learningcenter.sony.us] has the type of screen you want, which is an eInk technology. I don't know when color will be generally available, but they do have prototype color displays now.
    • Re: (Score:2, Informative)

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

      But otherwise, yeah it meets his requirements.
    • Re: (Score:2, Informative)

      by geekboy642 (799087)
      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.
    • eInk is great if you don't need to refresh the display much.
      It is useless for any type of scrolling display or animation.
      For an Ebook, clock, or watch it isn't bad.
  • by jbarr (2233) on Saturday April 14, 2007 @09:08AM (#18730697) Homepage
    "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.
    • I know everything is better in Japan blah blah blah, but I do have a cell phone (the V603SH by Sharp) that I got from Vodaphone here in Japan, and it looks great in any light.

      This might be what the writer is looking for, in general. The screen's great, anyhow, and small.
  • Priorities! (Score:2, Funny)

    by dour power (764750)
    I'm pretty sure you would have other things [wikipedia.org] to worry about if you were in the sun.

  • Just remember to stop reading when all that oh-my-god-in-burning stuff begins!

    --
    Text link ads, the easiest way to earn money with your web [text-link-ads.com]!
  • 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.
  • The problem is finding a laptop capable of withstanding the enormous heat and pressure found in the sun! ;-)
  • I've had the same question...

    I don;t like the current trend toward "shiny" displays on laptops.

    What I'd really like to have is a filter I can put over a TFT display for times when I need to use a laptop outside. By saying "I've Googled and can't find anything" (which I have), I hope some wise-arse Slashdotian will inflate their ego and show me where such a device can be found.

    • by TheSHAD0W (258774)
      I don't think it's possible; I've found the sun will overpower the backlight of any notebook out there. The only solution is to throw your jacket over your head and look at the laptop like it was one of those old LF cameras.
      • GE-FANUC has recently acquired Computer Dynamics who makes a ruggedized product that they call a "Wolverine" which uses a laptop motherboard and has a sunlight-readable display and is encased in an explosion proof case for use in industrial and petroleum situations.

        http://www.cdynamics.com/ [cdynamics.com]

        http://www.cdynamics.com/sunlight-readable-display s.html [cdynamics.com]

        So technically, it's a laptop that you don't have to throw your jacket over your head to see. Although it's not nearly as portable as my HP, and I can't see my HP
        • by xenocide2 (231786)
          It's actually quite simple to explain the hardware. In essence there's two kinds of screens, one that fight the ambient light and ones that rely on it. Some screens act as filters to a backlight -- this backlight has to fight the ambient light if you want to see anything. Others reflect the ambient light -- without light they're hosed. Reflective screens block the light behind them. Engineering a solution that works in both cases is tricky, but doable for small screens. The GBA SP had a reflective screen, a
          • by iamacat (583406)
            Is it really necessary to fight the sun though, or can fiber optics leads from other parts of the notebook redirect additional light behind the screen?
  • I know that some mobile phones have polarized filters on the display glass to improve outdoor viewing. So if you're going to be outside with polarized sunglasses, double check that they don't mess up your carefully selected display.

    Otherwise you might see a very dim or black display.

  • Motorola are making a phone designed for outdoor use, using an eink/epaper display, according to some articles [eink.com].

    You could buy some eink stuff for test purposes, and see if it's as good as they make out.
    • by emj (15659)
      Why would you want to use a mobilephone outside? Trust Motorola to come up with useless concepts, I don't see SonyEricsson or Nokia doing stuff like outdoor phones.. Phew!
  • Solarism (Score:3, Informative)

    by Xerotope (777662) on Saturday April 14, 2007 @11:43AM (#18731891)
    We work outdoors a lot with our robots, and we found the best solution to be monitors made by Solarism [solarism.com]. They're kinda pricey, but they put out nearly four times the brightness of a standard LCD.
  • Cannot do (Score:3, Interesting)

    by thsths (31372) on Saturday April 14, 2007 @12:30PM (#18732305)
    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: (Score:2, Interesting)

      by cpaglee (665238)
      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.
      • by TeknoHog (164938)

        The 1000 watts of light per square meter is based on the amount of light from a 1000 watt incandescent light bulb.

        I'd like to clarify that the 'solar constant' isn't really tied to the way light is produced in bulbs. The point is that the 1000 W/m2 is total power over all frequencies of sunlight from IR to UV. Visible light is a rather small fraction of that.

  • 300? (Score:4, Funny)

    by vertinox (846076) on Saturday April 14, 2007 @01:04PM (#18732619)
    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.
  • Take any modern LCD, and remove the case. The panel itself is clear with a stack of filters behind it to even out the backlight (look for panels that won't have wires obscuring the back. Ask for advice at the Lumenlab forums.). All you need to do is remove any opaque layers. Hold up the panel toward the sun so that the sun shines through the filters, acting as the backlight. You needn't remove the original backlight, so the display can still be used in darker environments.
    In short, use the sun as the
    • by cpaglee (665238)
      This will not work. The back light in an LCD is actually not a backlight at all. It is a 'side light'. The light is a long CCFL lamp which looks like a very bright miniature fluorescent lamp. They shine through the entire LCD through a prism effect. Puting a light bulb behind the LCD or holding the LCD up to the sunlight will not work, at least not for my LCD. One thing you COULD try is replacing the CCFL in your LCD with a more powerful bulb. You would also have to change the Inverter used to power the CC
      • by nerd65536 (692353)
        The LCD panel itself is a (mostly) transparent piece of glass. Put a diffusion filter over one side and hold it up to a light source. See also: LCD projection panels. Putting a LCD projection panel, with a diffusion filter, on top of a sufficiently bright overhead projector (we won't be projecting, just using it as a light source (backlight)) would also suffice for sunlight viewing.
  • The Garmin GPSMAP 60CSx [garmin.com] is built to be used in the sun, and its LCD is easily visible in bright light--the brighter, the better, in fact.

    --Bruce

  • ePaper (Score:2, Informative)

    by Meneth (872868)
    I recommend e-paper. The device I've tried, the iRex iLiad [irextechnologies.com], works in all well-lit environments. It even runs Linux.
  • A LiteBrite!
  • by evilviper (135110) on Saturday April 14, 2007 @06:34PM (#18735637) Journal
    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.
  • As I recall, it was really easy to see in the sunlight..
  • by Castar (67188)
    I have a Sony Reader with the e-ink screen, and it's more readable the brighter it gets. They have a roadmap towards color (and some working prototypes) although I'm not sure when it's scheduled to arrive. The upsides are low power usage, sunlight readability, and crisp, paper-like images. The downsides are probably expense (I don't know how much the components cost, but my Reader was $350 retail, which suggests the screens are expensive), low refresh rate (on the order of .5 seconds per refresh at best -

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