Different color LED's in optical mice

[Gerbil333]

What's the deal with all optical mouse manufacturers using red LED's? Does anyone have any scientific or technical data that suggests why red is better?

Last week I decided I wanted to change the standard red LED in my Logitech optical mouse to blue. I picked up a 2600mcd, 3.7V blue LED from Radio Shack and modded my mouse. It works great Since then a few friends have asked me to mod their mice. Here's what I've modded so far:

Microsoft Blue: Blue LED (2600mcd, 3.7V)
General Electric Deluxe Optical: Blue LED (3500mcd, 3.6V)
Microsoft Explorer 3.0: Green LED (5600mcd, 3.6V)
Microsoft Explorer 1.0: Blue LED (3500mcd, 3.6V)

All the mice work fine, if not better than before on standard mouse pads. The mice that I installed blue LEDs in work poorly on a certain wooden desk I have. The desk is a very dark wood (walnut?) with a fairly smooth gloss coating. Before the mice were modded (red LED's), they worked alright on this desk. The mouse with the green LED also works fine on the desk...what's with that? I can visually tell a difference between the 2600mcd blue LEDs (From radio shack) and the 3500mcd blue leds (from LSdiodes.com), but the brightness seems to have no effect on how well the mice work on that desk. The green LED is extremely bright, and it works perfectly on all the surfaces and colors I tried: blue, green, red, yellow, white, the wooden desk, and cloth mouse pads.

The modded mice are actually more responsive than they were with their standard red LEDs when used on the dark colored cloth mouse pads I use. Since the green LED works perfectly on everything I've tried and the blue LED's work on everything except that particular wooden desk of mine, I dont know if it's the color or the mcd (brightness) rating of the LEDs that determines what they will work on.

I'm not looking for help. All the mice are working perfectly. None of them will be used on my wooden desk. They're all on mouse pads. That was merely an observation I made. All I want to know is why they perform this way and why red is the only color LED used in optical mice.

 

[PliotronX]

Because the sensors are most sensitive to ~630-680nm color (red-deep red almost infra) see graph from another thread so the manufacturers can use less bright (cheaper) LEDs to get the mouse to work. I've also found that modded opticals seem more responsive. I've got a 10cD bluish-green and a 6cD blue in a Dual Optical and it was much more accurate afterwards.

 

[fredtam]

Also red increases contrast. The more contrast the better the performance.

 

[Gerbil333]

Originally posted by: fredtam
Also red increases contrast. The more contrast the better the performance.

Then why do my mice seem to perform better than before? The other guy said the same thing. I'm using a dark blue cloth mousepad with my 2600mcd blue LED Logitech mouse and a black cloth mousepad on my 5600mcd green LED MS Explorer 3.0.

 

[fredtam]

Could be a couple of things. "seem". Did you benchmark them somehow? The other is the sensors which may in fact work better with different colors. Also since the contrast is increased red is more likely to work on varied surfaces like your dark wood desk.

 

[Gerbil333]

I didn't do any official benchmarks, but I did do this:

Before modding my Logitech mouse, I moved the mouse back in circles or left & right or up & down gradually faster until the mouse mouse couldn't keep up and the pointer would go crazy on the screen. I tried this same test after modding the mouse. It seemed like I could move the mouse much faster before it lost control. There's no way to benchmark a mouse that I know of, and that was the best I could come up with.

 

[Jeff7]

And red LED's are cheap. You can easily get 10 high brightness red LED's for $1, whereas a white or blue LED of similar brightness will run you $1-2 apiece. Pure green LED's are hard to come by too, and they are usually $2.

 

[Tab]

Anyone know the specs of the Siebel | Microsoft USB Opitcal Notebook Mouse? What blue led can I replace it with

 

[Gerbil333]

Out of all the mice I've modded, and all the mice I've read about, 5mm LEDs are used. I'm going to make a pretty confident guess that your mouse also uses a 5mm LED. Next, the voltage supplied to the LED is roughly 3.2-3.7V from what I've seen. Get anything within that range. The lower the better, because LED's can be overpowered to increase their brightness. The last thing you need to look for is the mcd/brightness rating. The dimmest LED I used was 2600mcd. It works great, but the higher the better.

Go here: LSDiodes.com. That's where I got my latest batch of LEDs. Any 5mm LED they have will work (I think the UV and IR will even work). I ordered 9 of their 5mm blue LEDs (3500mcd typical, 4000mcd max) and 1 green LED (5600mcd typical, 6200mcd max) all for $0.45 each. Shipping is a flat fee of only $2, and they ship fast. I got my LEDs in only a couple days. Make sure and read their "Freebies" info. They give you free LEDs depending on how many you order. Since I ordered 10 total, they gave me 1 free 5mm blue LED.