Converting a scanner into a touchscreen

[Sprite_TM] was cleaning up his hacking workbench when he came across an all-in-one device that had seen better days. After a bit of consideration he decided to tear down the scanner portion of the device and ended up turning it into a multi-touch display.

The scanner relies on a long PCB with a line CCD sensor. This sensor is read in a similar way that information is passed along a shift register. Tell it to take a reading, and then start a clock signal to pulse out each analog value from the pixels of the sensor. In order to scan color images it uses multicolored LEDs to take different readings under different illumination.

[Sprite_TM] takes advantage of this functionality to turn it into a multitouch sensor. The sensor board itself is mounted below an LCD display along with a shield with a slit in it to help filter out ambient light. Above the screen a series of LEDs shine down on the sensor. When you break the beams with your finger it casts a series of shadows which are picked up by the sensor and processed in software. Watch the clip after the break to see it for yourself. It has no problem detecting and tracking multiple contact points.

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Phosphorescent Laser Painting

Here’s a simple and interesting idea that increases the visual persistence of a laser scanner image. Using glow-in-the-dark paint, [Daito Manabe] prepares a surface so that the intense light of a laser leaves a trace that fades slowly over time. He’s using the idea to print monochromatic images onto the treated surface, starting with the darkest areas and ending with the lightest. The effect is quite interesting, as the image starts out seeming quite abstract but reveals its self with more detail over time.

As evidenced in the test videos, the bursts of laser scanning are matched to the fade rate of the paint. Therefore it would seem that the time taken to “write” an image is directly proportional to the desired visual persistence of the final image. We wonder, by combining clever timing and variable laser intensity could you write images much more quickly? How hard would it be to use this for moving pictures? With the ability to create your own tiny laser projector, and even an RGB scanner, there must be a lot of potential in this idea for mind-blowing visual effects. Add portability by using a phosphor-treated projection screen!

Share your ideas and check out the test videos after the break.

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LEGO barcode scanner

Playing store just got really, really fun because you can now build your own LEGO barcode scanner. As you can see after the break, it works well and it’s fast like a real barcode scanner. Unfortunately it doesn’t scan real barcodes. Or at least not traditional ones. As we learned in the Barcode Challenge, standard barcodes are a set of white and black bars that make up the ones and zeros of the code. This system uses the same white and gray bar system but it seems that it’s only the number of bars that identify an item, not a code created by a particular combination of light and dark. The items above are all scannable because the scanner counts the 2, 3, 4, 5 or 6 white beams on the bottom of each package. Still, it’s incredibly clever and a great toy for the young hackers to build if they have a little help.

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Hackaday links: October 17, 2010

Cards you should crank

These greeting cards must be the product of a mechanical engineer run amok. They come with a crank and are designed to entertain with their simple, yet elegant movements. [Thanks Phil]

Magnetic card stripe reader

[JP] built an Arduino based magnetic card reader. It uses off-the-shelf parts but if you don’t mind buying the components this will get you up and running in no time. If you want more info there’s also this Teensy based version.

Homemade Airsoft sentry gun

This sentry gun has an amazingly fast firing rate that can continue for quite a while, thanks to the big flashlight housing that is holds a lot of ammo. [Thanks David]

Scanner easter egg

The engineers over at HP had a little fun building an easter egg into this scanner. If you know what you’re doing you can get it to play the Ode to Joy. It needs to join the old-hardware band from our Links post earlier in the month. [Thanks Googfan]

Cheap(er) biometric gun safe

[Greg] sent in his biometric pistol safe lock. He keeps his guide light on details so not every Joe can crack the system (there is a thread to sift through if you really wanted to), but the idea runs fairly simple anyway. [Greg] took an old garage door opening fingerprint scanner and wired it into a half broken keypad based pistol safe. While he did have some issues finding a signal that only fired when the correct fingerprint is scanned, a little magic with a CMOS HEX inverter fixed that problem quick.

This does bring one question to our minds, are fingerprint scanners as easy to crack as fingerprint readers?

Ditch the LPs and build your own 3D scanner

Find yourself an old record player, a laser level, and a digital scanner and you can build a 3D scanner. That’s what [Rob] did. The camera and laser level are mounted on the turntable for steady rotation. The camera captures the vertical laser line traveling around the room by recording 30 fps at a resolution of 640×480. This data is then translated into a Blender 3D file via a Python script and the Python Image Library. You can scan a whole room or just a small object. The face above is the result of this image capture after a bit of processing. [Rob] found this worked best in the dark and when scanning surfaces that are not reflective.

Make sure you also check out the camera-and-projector scanning method.

Update: Realtime 3D for you too!

[Kyle McDonald] has kept himself busy working on 3D scanning in realtime. He’s posted a writeup that takes us through the concepts, tools, and assembly of a DIY 3d scanning camera. You should remember a preview of this method posted earlier this month, but now it’s time to build your own. You’ll need a camera, a projector, and some open source software to process the image data. Using these simple tools, [Kyle] turned out much better video than before. Take a look after the break to see his results from scanning at 60 fps using a PS3 Eye. The trick to this setup is getting the correct synchronization between the projector and the camera, something that could be improved with a bit of extra hacking.

Does [Kyle's] name sound familiar? It should, he’s got a long history of quality hacks that we’ve featured over the years. If you’re looking to use a scanner as a multitouch, add some music to tea time, or play with your skittles his work will give you a shove in the right direction.

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