Mouse IRLEDs.

[ian field]

A very old optical mouse I took apart had one water clear IRLED and one with
a near cyan tint.

Does anyone know the significance of this difference in appearance?

TIA.

 

[Lostgallifreyan]

"ian field" <gangprobing.alien@ntlworld.com> wrote in
news:UgiJl.30267$a%2.19344@newsfe24.ams2:

A very old optical mouse I took apart had one water clear IRLED and one
with a near cyan tint.

Does anyone know the significance of this difference in appearance?

In green DPSS lasers the IR blocking filter is a sort of cyan colour. While
an IR LED shouldn't be blocking IR entirely, it might have used a similar
filter to get a narrower IR spectrum than they'd otherwise get. This might
improve noise immunity in older systems made when LED's usually had broader
spectra than current new ones do.

 

[ian field]

"Lostgallifreyan" <no-one@nowhere.net> wrote in message
news:Xns9BFAAC5D74AD5zoodlewurdle@216.196.109.145...

"ian field" <gangprobing.alien@ntlworld.com> wrote in
news:UgiJl.30267$a%2.19344@newsfe24.ams2:

A very old optical mouse I took apart had one water clear IRLED and one
with a near cyan tint.

Does anyone know the significance of this difference in appearance?


In green DPSS lasers the IR blocking filter is a sort of cyan colour.
While
an IR LED shouldn't be blocking IR entirely, it might have used a similar
filter to get a narrower IR spectrum than they'd otherwise get. This might
improve noise immunity in older systems made when LED's usually had
broader
spectra than current new ones do.

I've seen a similarly tinted LED in a payphone but it wasn't obvious what
the opto-pair did as the payphone had been run over (several times) by
construction site vehicles.

 

[Franc Zabkar]

On Mon, 27 Apr 2009 14:18:42 +0100, "ian field"
<gangprobing.alien@ntlworld.com> put finger to keyboard and composed:

A very old optical mouse I took apart had one water clear IRLED and one with
a near cyan tint.

Does anyone know the significance of this difference in appearance?

TIA.

You can get some detailed information (schematics, parts lists,
operational description, user manual, internal/external photos) here:

https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm

For example, put "Memorex" in the Applicant Name box, and select a
Grant Date Range of 01/01/2000 to 04/27/2009.

You will see 4 results for Memorex wireless optical mice.

I have a very old Mouse Systems model M411 serial optical mouse which
uses a special metal tablet. It is covered by US patents 4364035 and
4546347.

The patent documents describe how it works:

http://www.google.com/patents?id=rOg5AAAAEBAJ&dq=patent:4364035
http://www.google.com/patents?id=nvktAAAAEBAJ&dq=patent:4546347

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.