This is one of my favorite pieces of engineering.
And I want to show you how it works.
I'm not quite sure how to take it apart
but I've got the manual to help me.
Its inventor, Chester Carlson,
demonstrated true innovation when he put together scientific phenomenon
that no one before had ever related.
Carlson read patent after patent, searching for ideas.
He learned of Electrostatics,
that's things that stick together because of static electricity,
and Photoconductivity,
that's light causing current to flow,
both of which are critical to the photocopier.
Alright, I now have the four key elements.
There is an aluminum drum coated with amorphous silica,
a wire, which is used to deliver a high voltage,
a 265 W halogen lamp here,
and then the very last item is toner,
which of course is what's all over my hands, and all over the floor back here.
Now let me explain how these work.
It takes 5 steps to make a copy.
First the machine sensitizes the drum
by raising this wire to a potential of 850 V relative to the drum.
This separates the air molecules between the wire and drum
into negative and positive ions,
which in turn creates a charge separation on the drum.
The insulated silica surface has a positive charge,
the aluminum interior, negative.
Second, a very bright halogen lamp scans the image.
Black areas don't reflect the light, but white non-image areas do.
When the light strikes the drum
the silica surface becomes conductive and
charge flows away leaving only a charged image.
Third, the maching wipes toner across the drum.
Toner isn't ink; it's tiny particles made of plastic and carbon.
Because it has a negative charge the toner sticks only to the positive image on the drum.
Fourth, the wire charges a piece of paper
so it can attract the toner from the drum.
Fifth and finally, a heater in the copier melts the plastic in the toner
to fuse the image to the paper.
Come in!
Becky says you took the photocopier?
*again*?
I'm, uh, I'm repairing it...
Well, so how does it work?
So, the drum goes down underneath here
and then there's a light that scans across the top.
and then the toner... [click]