gearwheel encodjng

[Ross Forgione]

This is not my area of expertise, but during the course of my normal day to
day employment I come across large band printers which have rotary encoders
on their carrige motors. These encoders use a standard "H" block Sensor to
detect gap/no gap. As it is optical, you donot suffer from the physical
parameters mentioned below. However, can anybody comment on how suseptible
to noise this arrangement may be.

Ah one important thing to mention, is that these units are sealed quite
well so dirt, grease etc should not present a big problem.

I am not shure what the pulse count per revolution is (I know its lots) but
I will check this out. I need to rat through the old printer bits room.

Ross


At 14:12 4/02/97 est, you wrote:
>>My problem is this, I don't know what the min. diameter of the wheel 
>>should be.  At 3deg. per tooth edge, the tooth length gets quite 
>>small as the diameter goes down.
>
>The standard HE flywheel encoder pickup will sense material some mm 
>before it passes the sensor axis, and also some mm after.  These 
>operate and release *distances* will limit your encoder diameter.  For 
>example, an 60-tooth encoder I designed at 210mm mean diameter, had a 
>~1:2 physical mark-space ratio for a 1:1 electrical mark-space ratio. 
> For a normal IC engine, the frequency response is not an issue if you 
>keep your electrical mark-space ratio near 1:1.  
>
>You'll need to test your pickup to determine the operate and release 
>distances unless you have the manufacturers specifications.
>
>
>
>
>
>
>
>
>