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Use this with the propeller (laser keyboard) — Parallax Forums

Use this with the propeller (laser keyboard)

BitsBits Posts: 414
edited 2012-06-30 05:03 in General Discussion
I think this is cool, I have seen the "entire units" for sale about 9 years ago so this technology is old but how do you see this running this with the propeller. Could you use a camera or some other sensor to detect that the keys were pressed? Keep in mind this is just the image of a keyboard.

I am might get one and try some things with it, but at the moment all I can think to use is a camera in conjunction with the laser.

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Comments

  • kwinnkwinn Posts: 8,697
    edited 2012-06-29 20:41
    Don't see why the propeller could not do this. Only requires knowing where the laser scanning beam is when a finger occludes the surface the keypad is projected on. This was done with counters for gaming "guns" aimed at a TV display several years ago.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-06-29 21:26
    @kwinn, I'm don't think this would work the same way as the gaming guns do. I don't think it generates the image from scanning, rather I think there's a small keyboard "slide" type image and the laser is just the light used to project the image.

    I think this is the same item.

    http://www.ebay.com/itm/Cube-650nm-Red-Laser-Module-for-Virtual-Keyboard-VKY-/170667605325?pt=US_Tablet_Accessories&hash=item27bc94fd4d

    bits' link didn't work correctly.

    I think this would be pretty tough to do with a Prop. I'm not sure how one would detect when a key is pressed. I don't know if any of the current image capture methods would be fast enough and with enough resolution to tell where ones fingers are on the keyboard.

    How would one tell when one of the keys under the fingers at home position are being pressed?

    Edit: I think I understand how these work better after reading the reviews on Amazon about a full unit. I think getting a Prop/camera combo to read keypresses from this projected keyboard would be very very hard. Maybe I should say it would be imposible, so someone would do it?
  • lanternfishlanternfish Posts: 366
    edited 2012-06-30 03:31
    Hi Bits

    Like Duane I did a bit of reading on these. Duane is correct re the projected image. Most of the commercially available products also 'flood' the keyboard area with IR (usually just above the projection surface) and a CMOS sensor 'captures' the IR reflection.

    So, rather than a camera you could consider the TSL1401 Linescan Imaging sensor (discussed in this thread & this thread).

    Good luck with the project.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-06-30 05:03
    Not very sure about doing this with a Propeller, but it could be very useful in some situations. And something simpler may even be more useful as a micro-controller interface - like a 3 x 3 grid.

    My desktop computing habits are often under dim light as my room has always been rather dark. I quite often find I am a bit frustrated by having an unlit keyboard. When I turn on the desk lamp, the glare from it makes the screen difficult to use.

    So a laser keyboard might be a win win situation. Though I think I would feel a bit funny pounding an empty table top.

    It is definitely not for bright light, but there are plenty of restaurants and bars that need both a lit keyboard and something that won't soak up spills.
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