Are LED's good for backlighting a display?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I want to illuminate my aluminium knob for my gainclone chasis. Basically, it is a 2" (5cm) diameter knob. A 2 and 1/8" (5.3cm) hole will be cut into the face plate. I want the space between the knob and the faceplate to glow. :cool:

What i've seen done in commercial amps/tuners when they want to illuminate a dial or display is they usually build a white, light-sealed background behind the display, then cover the display with a see through plastic and in the space between the white backdrop and plastic face, an incandecent lamp is inserted out of sight. This has the effect of making the white backdrop glow. For colour, a plastic coloured transparency is placed infront of the white bulb.

But, i think incandecents are too gready with current. I want to limit the current draw wasted on esthetics. LEDs draw less current so my question is:

What type of LED is good for this kind of back lighting over a relatively large area? Im looking for brightness and uniformity as well as low current draw.

Im also opened to other ways of lighting the space around the knob. thanks for any suggestions
 
Your going to either need a lot of LEDs, or a way to spread out the light.

To spread out the light you use a clear plastic, and drill out a hole in the middle to fit the knob. Then have a point where the LEDs light can enter. # of LEDs would depend on the size of the circle, and how even you want the light (in my ex. its 2 and fairly uneven, 4 would be better).

No idea what LED type would be the best.. but I would just get the cheap ones on ebay. As for colour, blue or red are very bright for low cost (and imo look the best).

I kinda suck at describing it so here are some example pics (notice the red on the right, blending colours looks cool, but brightness may be uneven).
 

Attachments

  • led front.jpg
    led front.jpg
    53.4 KB · Views: 217
I use them and, yes, they are really bright. :)

You may find it hard, if you use just a few, to produce an even light distribution around your knob without bright spots. Maybe, you shouldn't try. Perhaps you could use a bunch of inexpensive LEDs to produce diffuse, graduation bright spots around the dial.
 
homer09 said:
I see there are LEDs called superbright LEDs. They have an mcd in the thousands vs in the 50's. Anyone have any experience with these type of LEDs and are they really much brighter?
They're certainly brighter, but due to the way candelas are scaled, not hundreds of times brighter (any more than a 100W amp is 100x louder than a 1W). Most important in your application may be a wide viewing angle, which cuts down the cd rating but may give more uniform light.
 
Don't worry about the brightness of the LED--just use a variable resistor to raise or lower the drive current until you've got it where you want it. You can either leave the pot or replace it with a fixed resistor once you find a good level. There's no law that says you've got to run LEDs wide open all the time.

Grey
 
Why not try something using something like this:
http://www.minderresearch.com/greenlite.html

You could try cutting apart something like one of these ectroluminescent night lights, or there are panels are available. I also think there are a variety of colors. This is basically the same thing as Indiglo on wrist watches.

This would be small, flat, and wouldn't use much energy. Since the light comes evenly from the entire surface- it would be ideal for backlight.

I also have heard of OLED (organic light emitting diode) panels that would do a similar job, but with much higher light output. I don't think they are readily available yet though.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.