h’s Laser Dymo Clock

A quickie project. Two stepper motors, a UV laser, some luminous paper, an Arduino, a couple of ULN2803 drivers for the motors, and a “daisy wheel” printed onto transparency film.

After playing with some luminous paper and a laser pointer (UV ones work best – red ones don’t work at all), I thought of making a little laser display board thing. I thought about using galvos to draw the characters on, but the mechanics of it would have turned it into a bigger project than I’ve got time for at the moment, so this mini-projector approach will have to do.

Next step is to reduce all the electronics onto a single PCB to mount on the back of the wooden board…

Other thoughts:

• There’s a tradeoff between how bright you can make the text, versus how often you want to update the display. You can make the text brighter and last longer by lluminating it for longer, or, as this clock does, by going back over the same text a few times, but if you then want to write new text over the old, you’re still left with the ghost of what was there before
• There’s lots of things you could use this idea for. Because the text starts fading as soon as it’s written, it’s ideal for showing any ephemeral data. A clock was obvious, but a continuous stream of headlines from an RSS feed could be cool, too
• You could stick a large sheet of luminous paper on a wall (possibly in a frame), and then have a laser write the messages or draw a clock face and hands from the other side of the room
• Because the paper doesn’t respond to many wavelengths of light other than the blue/UV end of the scale, there’s nothing to stop you using red and green LEDs to illuminate the workings a bit better
• Rather than using a disc of paper to write on, you could stick lots of strips of luminous paper together to form a long band, and run it round pullies for a more ticker-tapey effect