Display technology

Hi all

I’m gonna be drawing a long bow here.

Basically what I need to create, is a display of some sort - kind of like an LCD, but where the face is a nice flat silver or black - no indents, marks, nothing.

What I need, is to be able to have, for example, a moving LED of sorts - that can follow a set path - a light dot, that simply appears to, from nowhere, move about and around the panel.

As there’s no pits or spots on the panel for these lights to travel across (viewable from the outside), i’m guessing they somehow need to be “projected” from behind the panel - without casting too much light “overspray”, if any. I guess they could be mechanical, and sit in a groove behind the panel.

If anyone can visualise what i’m getting at or needs more info, it would be much appreciated.

What sort of panel materials, which can project a one way light (kinda like a one way mirror at a cop station) exist? What would the best method be to give the desired result of a dot of light travelling around a flat panel?


Depends how bright you need it. If you need the panel to be completely transparent to light from the inside, but completely opaque from the outside, you’re out of luck (unless you’d go for some exotic liquid-crystal and switching hardware).

The simple solution is to go with the same ethod they use for those mirrors in police stations; it’s just a semi-silvered mirror, but the intense lighting in the interrogation room and the dim lighting in the observation room means that you can sort of see into the bright room from the dark one.

SO what you do is you use a piece of semi-silvered plastic, or dark (smoked) acrylic/PC/whatever. If the lights on the inside are bright enough - say one of the new blue LEDs - then they’ll show through at about the same brightness as a display. My Samsung DVD player has almost this exact feature; it uses a VFD (vacuum fluorescent display, a very bright display like the green ones on older cash registers before they went to LCD) behind a sheet of silvered plastic. When the player’s off, it’s a silver faceplate; when it’s on, the display shows through.

Note that this only works for monochromatic or LED-based technologies. If you want a full-color LCD panel or something, you’d be better off using a regular panel with a sheet of clear acrylic over it, and do some bezel vooodoo to make it look right.

Hope that helps; it’s a little hard without more information about the exact effect you’re trying to achieve (display on the surface of the panel, or behind it? Matte or gloss finish? color or monochrome? brightness? large indicator lights or a detailed readout?)

Use a rear projection screen:

For the dot, you could use a programmable laser, or a data projector.

infrared or resistive touch screens

Excellent, thanks a lot for the responses guys.

Cost isn’t so much of an issue, i’m prepared to investigate any methods that may get the desired result.

What i’m after exactly, is just a hard plain matt (or gloss even) face, with two single colour (blue) lights projecting from behind, and showing on the front and fairly sharp edged lit circles, which travel around it. Pircure a black dinner plate, with a blue circle travelling around the perimeter.

I gather a laser could be the go then? Infra red? I do like the rear projection idea, as long as it can produce the desired effect…

And another question -

I’m after a metal material, that could best be described as black chrome. It has all the reflective qualities of silver chrome, yet the material itself is black - does such a metal or treatment/compound exist, and is it durable (ie - able to withstand everyday dings and knocks, and scratchproof)?