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Cheap, Small LED or LCD Touch Sensitive Screens?

Posted by ryuzaki0 on from the off-the-shelf-or-DIY-project dept.

emf2268 asks: "I'm looking to either purchase or build (I'll do the circuitry myself if I have to) several dozen, small screens for an arcade game that uses a touch interface. Each screen, which should be around 6-10 inches, needn't be extremely advanced in the display department, since 16 colors will do just fine. An LED or LCD would do the job. But each screen also needs to be touch sensitive...it only needs to know if it's been touched, not where it was touched. How, can I build this as cheaply as possible?"

39 comments

  1. glasspane by yincrash · · Score: 3, Informative

    the cheapest way to do this is to probably have a small (plexi)glass pane over the cheapest display you can find and have the glass pane be resting on a bump switch(sensor) that has enough tension to hold the glass up but will register when it is touched.

    1. Re:glasspane by Baddas · · Score: 1

      I concur with this one. Make them as bulletproof as you can get them, if the construction of DDR is any guide to go buy, steel, rivets/welding, and 3/8ths thick (or thicker) plexi is the way to go.

      Design it as though an elephant will stomp on it, and then maybe it'll last long enough for you to enjoy it

    2. Re:glasspane by yincrash · · Score: 2, Informative

      to extend upon this, you want to make sure that when the pane is pushed down, it doesn't actually touch the screen. i'm sure there is a way to mount it so when fully depressed it is barely above the screen.

    3. Re:glasspane by bill_mcgonigle · · Score: 1

      i'm sure there is a way to mount it so when fully depressed it is barely above the screen.

      some rubber bumpers on the screen frame might be good insurance.

      --
      My God, it's Full of Source!
      OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
    4. Re:glasspane by SEWilco · · Score: 1
      some rubber bumpers on the screen frame might be good insurance.

      Rubber baby buggy bumpers?

    5. Re:glasspane by WgT2 · · Score: 1

      Is there any other?

  2. What I use by 110010001000 · · Score: 2, Informative

    What I have done in the past is to buy a bunch of old Windows CE.NET devices off of Ebay and use their touchscreens. For some (like the Aquapad) you can even get Linux drivers - search for Midori Linux and Aquapad.

    Its certainly cheaper than trying to source new screens.

  3. A cheap way to do it by rblancarte · · Score: 1

    I would say get LCD screens that you can mount onto buttons yourself. Since you only have to recognize touch (and not location), it would probably be much cheaper than purchasing touch LCD screens, since most of them are designed to tell you where they were touched.

    I would say mount 5 buttons on the back (center and each corner) and then wait to see if the screens were "pressed" by checking all buttons. If any register a touch - then the screen was "pressed".

    RonB

    --
    It is human nature to take shortcuts in thinking.
    1. Re:A cheap way to do it by yincrash · · Score: 1

      i'm going to have to say it's proably a bad idea to be putting force on the actual lcd screen itself if you're going with lcd. after a couple of months of finger pressure on the lcd, you're probably going to start showing up marks or dead pixels. this method puts too much stress on the lcd.

    2. Re:A cheap way to do it by Anonymous Coward · · Score: 0

      read the post that came before the parents post, whoevery my parent is. If both are combined, it will do the job. But, as most know, its best to look at as much ideas as possible, identify the unique ones, find the right path, then combine the detials of how to go about it, each post will probably add something new, that when combined with others, will show better ways of doing this, or that. In this case, the 5 buttons are a good idea (the post before this parent had the idea to put plexiglass in front, with buttons hidden on the side. Ill add, that to avoid touching the LCD (as one of its children complained would happen), to put the buttons a bit forward, and add a rim anoud the LCD, so the glass cant touch when its pressed, if you have strong glass, and a good rim distance, it could probably survive a sledgehammer hit, or at least a punch from a guy who lost). Altho the 5th center button would be a problem, the others will ensure it was pressed.

      Alternativly, you could have the rim around the LCD as the "button", with springs or something on the side (maybe a magnet strong enough to keep the distance, but soft enough to allow a push, or mounted far enough away to allow the needed specs (it wouldent ware out, no moving parts). Also, with this rim-button approuch: If you can, mount wires on the board, a plate that will conduct a button "press" if it touches the rim, then even the "button" cant ware out do to worn springs, or rubber doms that break, but im no expert, not in the least, and im probably missing something, im not even sure if the magnets would work, or if they would give to much resistence when pressed, and not even force to hold the glass if its back to far due to try and reduce the resistence. But, like i said, look at several posts, some ideas might be bad, or plain wrong/broke, but have some detail that could be applied to other ideas to improve your solution.

  4. PPR? by Anonymous Coward · · Score: 2, Funny

    Punch Punch Revolution?

    1. Re:PPR? by Anonymous Coward · · Score: 0

      I don't care what anybody says. That's funny.

  5. Single button screen by Ydna · · Score: 3, Informative

    If all you need is to detect a press anywhere on the screen without regard for where it was touched, just get small LCD display guts and float them on spring loaded contact switches and wire that switch up to some input.

    --

    "The great thing about multitasking is that several things can go wrong at once." -me

    1. Re:Single button screen by serutan · · Score: 1

      Yes, I like this better than the separate piece of plexi over the screen, and it's probably the simplest possible answer. You might have to use 4 microswitches wired in parallel behind the corners of the display to guarantee that one of them gets pressed no matter where the display is pressed.

  6. Yes. by Anonymous Coward · · Score: 0

    Yes.

  7. Do not thump the game of G'Quon! by AndroidCat · · Score: 4, Insightful

    Unless your game is Sim Paint-Drying, I think you'd be better to have an actual switch to press rather than have the player press the screen. Excited humans don't know their own strength, and I've seen industrial coin-op joystick that were yanked out by the roots.

    --
    One line blog. I hear that they're called Twitters now.
  8. Real cheap by Peter+Simpson · · Score: 3, Interesting

    If I were trying to do this on the real cheap, I'd use conductive bags. Cut a square of the material, place it backwards (inside out) over a plexi backer, with the LEDs behind it. A non-conductive) bezel over the front to keep all in place. Connect the conductive inner layer of the bag material to a high impedance circuit with a spring contact and sense the "body antenna effect" (as on the old microwave ovens),

    It's much cheaper than metallized glass. But maybe you want to go that way.

  9. Old fashioned way by cyber_spaz · · Score: 2, Interesting

    Back in the day, we used to see articles for homebrew touch screens that were basically picture frames with a few infrared LEDs on one side, and some phototransistors on the other with a bit of circuitry. Your finger would break a beam and get detected.

    For a tiny production run, this might be an acceptable method. (For a *real* product, you'll want something better.)

    Another thought: If you can get a conductive transparent plastic sheet, then you could make a sandwich where one sheet is against the screen, and the other is floating a small distance away. Then you can just detect the conductivity change when someone pokes the top sheet enough to make it touch the bottom sheet.

    --
    "Time flies like an arrow, fruit flies like a banana" --Karl or Groucho, I forget...
    1. Re:Old fashioned way by name773 · · Score: 1

      that's how the touch screen works on palm devices, except they use a grid for the underlayer, but same concept.

  10. As the adage goes by Dachannien · · Score: 3, Insightful

    Cheap, small, and good. Pick any two.

    1. Re:As the adage goes by GreyWolf3000 · · Score: 1

      Cheap, small, good, and having someone with a good imagination around. Pick any three.

      --
      Slashdot: Where people pretend to be twice as smart as they really are by behaving like children.
    2. Re:As the adage goes by Anonymous Coward · · Score: 0

      I thought it went, cheap, small, and legal but I've mixed up my adages.

      It's somebody's line about project management: you'd want it legal, on time, under budget. Pick two.

    3. Re:As the adage goes by Anonymous Coward · · Score: 0

      I wouldn't mind cheap good and LARGE LCD-display.

  11. You can use an LED matrix as both display & se by saccade.com · · Score: 5, Interesting

    It turns out you can use LED arrays as both displays and sensors. People have successfully used them for touch sensor controllers. See this blog for some experiments. The original concept came out of the NYU media lab.

  12. Touch panels are cheap and easy... by Facegarden · · Score: 5, Informative

    Resistive touch panels (not including the screen) are incredibly simple and cheap... They can register position, but if you don't care, you can still use them to see if they've been pressed. Get some palm-pilot touch panels, peel off the overlay on the back for the graffiti section, and you have a nice ~4 inch touch sensor. Buy custom sizes from a place like 3m or digikey, or get old palm pilot touch panels (no screen, just the touch part) for $4 each from http://www.halted.com/ Look up how they work... they basically act as a voltage divider when pressed... a simple comparator circuit is all that you need to register a press, and it's much more elegant than resting the screen on a push switch... -Taylor

    --
    Worldwide Military budgets: $2100 billion. Worldwide Space Exploration budgets: $38 billion. Really, world? Really?
    1. Re:Touch panels are cheap and easy... by ivan256 · · Score: 1

      Last time I called them (about a year ago), 3M sold a sample quantity of conductive/resistive transparent film for $900. It was a decent deal if you wanted touch sensitive displays in bulk, but for one-off projects of a custom size it seems like you're out of luck.

      Digikey has all sorts of driver ICs, but I don't see anything to actually make the touch sensitive surface there. Am I missing something?

    2. Re:Touch panels are cheap and easy... by Facegarden · · Score: 1

      3m sells pre-made glass or plastic panels with the leads and everything all ready to throw on a screen or whatever... though I'm not sure through who. I thought digikey sold them... maybe it's Arrow... I know I've seen them recently... Maybe they weren't 3M... Maybe search for "resistive touch panel supplier" or something and see what you get... -Taylor

      --
      Worldwide Military budgets: $2100 billion. Worldwide Space Exploration budgets: $38 billion. Really, world? Really?
  13. Optimus Keyboard by Chimera512 · · Score: 2, Funny

    just get an optimus keyboard, they have lots of OLEDs and it's touch sensitive since it's a keyboard. http://www.artlebedev.com/portfolio/optimus/ oh, you may have to wait a little while for the release of this product, the prototype will be ready any day now...can't wait to use it to play DN Forever.

  14. Saw these touch screens on Make by Anonymous Coward · · Score: 0

    http://www.makezine.com/blog/archive/2006/02/touch _screen_for_39.html

    These seem to be just overlays for LCDs, but they are pretty cheap. I can't vouch for quality, though; I just remember seeing the link and almost buying a couple.

  15. LCD touch by nan0 · · Score: 5, Informative

    earthlcd has been a savior on many a project

    http://store.earthlcd.com/

    if you really just need on/off - do the spring loaded, or piezo, or even IR (www.acroname.com - sharp ir sensors)

    if anyone has any other leads on cheap overstock LCDs... post away!!!

  16. three interesting ways to do it by dr_leviathan · · Score: 2, Informative

    (1) capacitive switches -- inexpensive, digital (on/off)
    This reverses the idea of protecting a high-impedance circuit from stray capacitance introduced by a limb or finger -- turn your accidental 'people detector' into just that:

    http://www.discovercircuits.com/C/capacitance-sw.h tm

    (2) frustrated internal reflection -- not necessarily cheap (needs a camera), or easy (needs video analysis) but can handle multi-touch and large screens
    The idea is to shine light in from the side of a class or plastic screen, and have a camera look at the backscatter introduced by finger contact, which scatters the sidways light rather than allow it to reflect at the bounary. The camera turns the touch events into a video stream which is then analyzed to compute touch events.

    http://mrl.nyu.edu/~jhan/ftirsense/index.html

    (3) strain gages -- not necessarily cheap ($5 - $8 for each strain gage) but can provide a very sensitive analog signal with wide dynamic range.
    Put some strain gages on several centimeters of half-inch square steel tube and you can easily measure touch events, as well as strong pushes.

    http://www.omega.com/literature/transactions/volum e3/strain.html

    Here is a simple, inexpensive (if you make it yourself) amplifier for strain gages that I've tried, and can vouch that it works well:

    http://www.staramp.com/

    --
    Religion is poison to rationality, and we lose sight of that at our own peril. -- Lurker2288
  17. In-car LCD screens? by scdeimos · · Score: 1

    LCD screens for in-car DVD systems are available in the 6- to 10-inch range, in 4:3 and 16:9 aspect ratios, and are getting cheaper all the time.

    Although they tend to have composite or S-video inputs (you're not really after high resolution, are you?) there are some now getting VGA inputs and touch screens for in-car computer applications. You can just register that the screen has been touched and ignore the actual location.

  18. LED interface.. looks like it could be cheap.. by euxneks · · Score: 2

    I found this neato LED interface the other day from hackaday
    Some more links to projects like this can be found on the story on hackaday.

    --
    in girum imus nocte et consumimur igni
  19. You should look at this by LarsBB · · Score: 2, Informative

    LEDs are photodiodes too! http://mrl.nyu.edu/~jhan/ledtouch/index.html

  20. Why several dozen? by cgenman · · Score: 2, Insightful

    Why several dozen for an arcade game? Will this be used as a prototype menu interface, or are kids going to be thumping on this thing with rubber mallets at the museum of science?

    --
    The ______ Agenda
  21. They're no good... by pelrun · · Score: 1

    Good thing you didn't buy any, the few people who did discovered they are just a cheap plastic sheet with a push switch at each corner. You can build a similar mechanism from spare parts easily enough.

  22. Re:You can use an LED matrix as both display & by stienman · · Score: 1


    Note that these require a lot of circuitry to run, and all prototypes currently only work in dark environments (the LEDs sense their own light, sure, but also room lights, sunlight, etc).

    Currently a neat hack with perhaps some niche uses, but not a good general solution.

    -Adam

  23. simple is best by ogarza · · Score: 1

    i would just go with a glass panel to take the beating and fingering and a couple of infrared LED emmitter/detectors.. only reasoni see for using the actual touchscreen was if position was important, and it also sounds liek you are trying to make a game? or wh the just detect if touhced or not? touchscreens are less touchable