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Thread: Projecting texts on large area outdoor cheap (used hardware) possible?

  1. #1
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    Question Projecting texts on large area outdoor cheap (used hardware) possible?

    Hello.


    I am interested in whether a laser projector can project text on an outdoor facade more efficiently (power consumption and visibility even in daylight) than a video projector.


    And if this is so, what kind of laser projectors could be considered for this.
    With attention to the second-hand market.
    I've seen projectors on Ebay for ~$38 final price.
    With XLR input (?). But I don't know if the projection of text is possible with it.


    Quasi a content-flexible digital laser version of a "GuerillaBeam".

    A video projector with 4000 ANSI lumens has a consumption of 325W (Sony...).
    And such a large distance would require a special lens.
    And during the day you probably won't see anything of the 4000 AL on an area of possibly at least 25ft wide (and 14ft high at 16:9).
    I hope that a laser projector would need less energy with better visibility.

    If this is correct, what are the price regions of possible (low) auction end prices on Ebay?
    It does not need high quality, it would just be a kind of better "LED running text".



    Thanks,
    Tobias Claren

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    To do this effectively you need multiple watt lasers and good scanners. Text is not trivial to project. It has a lot of sharp angles and can be as much as half blank. The projector isn't the only thing you need. You also need a way to make vector images of the text and a device for controlling the projector to display the text.

    That last bit is where I can help you.

    You also need to do this within the law.
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    You mean a do-it-yourself?
    I don't mean a do-it-yourself.
    Or is it cheaper and can be done by laymen?


    Vector images can be made online for free from any image file.




    What right?
    It is not forbidden to project with a video projector on public facades.
    A policewoman who took someone to the police station who was projecting criticism of the G8 onto the Hamburg radio tower received a penalty order for this and had to pay a fine to avoid criminal proceedings for deprivation of liberty.


    If you mean special laws for laser, it doesn't have to be super strong.
    If necessary, it can be as strong as a powerful video projector, and it doesn't have to work in blazing sunlight.

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    ... so why not use a powerfull video-projector instead of a dangerous laser? -- with proper animation you even can "simulate" laser-beams

    Viktor
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    See if you can find some people in your area who are already knowledgeable about laser projection. There's actually quite a lot to know.
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    Quote Originally Posted by VDX View Post
    ... so why not use a powerfull video-projector instead of a dangerous laser? -- with proper animation you even can "simulate" laser-beams

    Viktor
    Because there are no such powerful video projectors, or they are very expensive or used very rare.
    And special tele lenses for projectors are very expensive.
    Perhaps several thousand dollars (?).


    Laser projectors (with XLR) are available used from $38. Seems to start at $38, but probably just a few graphics.
    But I don't want a "show", and I don't want a simulation of laser beams, I just want to be able to put information legibly on large surfaces.


    I still have a 4000AL Sony.
    But where am I going to get the power...?
    A generator needs gasoline and disturbs.
    A lithium battery (for 325W) is big and expensive.
    And also 4000AL are not much light.


    Doesn't a laser projector need much less energy?

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    Quote Originally Posted by TobiasClaren View Post
    Laser projectors (with XLR) are available used from $38.
    A $38 laser projector will not be able to display text on a wall outside in broad daylight. You are comparing a child's rusty tricycle to a formula 1 race car.

    I don't want a "show", and I don't want a simulation of laser beams, I just want to be able to put information legibly on large surfaces.
    You are assuming that "just displaying text" is somehow easier than displaying a full laser show. This assumption is woefully incorrect. You need some sort of show playback mechanism regardless of what you want to display, be it text, graphics, abstracts, or even beams. You also need a means to create and edit the laser frame files that will be displayed. Fortunately, there are a number of options here, including some free or very low cost options.

    But more importantly, as explained above, drawing text using a laser projector is actually a difficult task. Remember that to draw anything with a laser beam, you must physically move a set of small mirrors (one for the x axis and one for the y axis). Any time you need to move something in the physical world, the laws of physics (specifically, momentum and acceleration) are going to be your limiting factors. Thus, you can only move those mirrors so fast.

    The best scanners currently available can only project perhaps 30 to 40 characters before the image starts to flicker. A cheaper projector might only manage 15-20 characters before the image begins to flicker. This is why most laser artwork tends to be minimalist by design; it's a fundamental limitation of the projector technology. When you see a laser projector displaying text, it's either just a few short words, or it is a scrolling text message, because of the limits of the scanning system.

    Then there is the issue of power. A $38 laser projector is not going to have enough power to display anything on a wall, outdoors, in broad daylight.

    To illustrate: I've successfully displayed images that were 20 ft square on a wall, outside, at night, with very little surrounding ambient light, using a 3 watt RGB laser projector positioned approximately 100 ft from the wall. That projector cost around $3000 and was just barely adequate for the job. It required about 350 watts of electricity.

    To do the same thing in broad daylight would require at least a 30 watt projector (which would be prohibitively expensive and would likely require 800-1000 watts of electricity), and even then the image would still be difficult to see. Trying to compete with the brightness of the sun is a losing game.

    Doesn't a laser projector need much less energy?
    Yes and no. Laser diodes themselves can be very efficient (as much as 30% for blue diodes), but there are lots of other loads inside a projector that must be powered. When you include the scanning system, the cooling system, and all of the internal power losses, the efficiency of the entire projector drops to just a few percent. Thus, an efficient laser projector that produces 3 watts of visible light might need 200-300 watts of electricity to operate, and some projectors in that power range need up to 500 watts of electricity to operate. (Note that this is a *huge* improvement over the gas ion lasers of 15-20 years ago; those lasers required 6 to 9 kilowatts of electricity to produce 3 watts of output.)

    Also, because the laser projector is drawing the image by moving around a single dot (the laser beam), you can't easily compare the optical power output of a laser projector with the lumen rating of a video projector. Often you need to perform multiple, side-by-side tests to determine how much power you will need.

    To summarize: projecting text onto a wall using a laser projector is a challenge, even at night. It can be done, but it will be expensive. Thus, it is almost always cheaper to use a video projector instead of a laser projector. Also, it is much safer to use a video projector. High power laser projectors will cause instant, permanent eye damage if not positioned and operated safely. (There are many legal issues to keep in mind as well, depending on the laws in your country.)

    Trying to project text onto a wall during the day is extremely difficult, no matter what technology you use. In this case, the laser projector is probably the better option, but the cost will be prohibitive.

    Adam

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    You wish to do this without VdE device approval, “Laserschutzbeauftragter” certificate, and German legal framework OStrV /TROS.?

    Nice words I've learned from my German friends at Laserfreak.de and industry conferences.


    Daylight laser has to overcome irradiance of 900-1100 Watt Per Square Meter to a daylight / scotopic eye which is already desensitized and iris stopped down. That needs a bright laser, and possibly (if not certainly) lasers in airspace clearance in case you scan past a target at that power level. . Not to mention text is anything but efficient at power conversion. Problem is surface has no means of contrast enhancement to help you.

    I suggest you check your regulatory framework, and wallet size, and have friends on site who are fire-fightsers. . Not to mention finding very fireproof walls to project on.

    That is one task direct view LED Walls will always excel at, even though I hate LEDS. Contrast enhancement in the led module physics makes it possible at far less power per unit area of light.

    You would need a very tight laser beam for this, at 30 watts or more. Must be a direct yellow or direct green laser, as those are the colors at the peak of vision. Most low cost 30 watt lasers are diode arrays with very fat beams. Energy density is low , but hazard is still very, very high, energy density per unit area is much lower then desired. Investing in 30 Watts of used OPSL laser will be 60,000 USD or more, your alternative is the ancient Ion Laser, and I assure you , that is not the way to go.

    Buy a LED wall, or used LED traffic sign, with tradeoff on viewing angle, and be happy.

    At night is a different story. Dark adapted eye is orders of magnitude more sensitive, and loves coherent light stimulation. Daylight eye, no where near as much. Laser excels at night.

    I understand what you are trying to do, but if the problem was that easy, everyone would be out doing it.



    Steve
    Last edited by mixedgas; 06-07-2023 at 14:21.
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