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This is one of my favorite pieces of engineering.

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And I want to show you how it works.

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I'm not quite sure how to take it apart

4
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but I've got the manual to help me.

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Its inventor, Chester Carlson,

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demonstrated true innovation when he put 
together scientific phenomenon

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that no one before had ever related.

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Carlson read patent after patent, searching for ideas.

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He learned of Electrostatics,

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that's things that stick together because of static electricity,

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and Photoconductivity,

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that's light causing current to flow,

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both of which are critical to the photocopier.

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Alright, I now have the four key elements.

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There is an aluminum drum coated with amorphous silica,

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a wire, which is used to deliver a high voltage, 

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a 265 W halogen lamp here, 

18
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and then the very last item is toner, 

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which of course is what's all over my hands, 
and all over the floor back here.

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Now let me explain how these work.

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It takes 5 steps to make a copy.

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First the machine sensitizes the drum

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by raising this wire to a potential 
of 850 V relative to the drum.

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This separates the air molecules 
between the wire and drum

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into negative and positive ions, 

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which in turn creates a charge separation on the drum.

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The insulated silica surface has a positive charge, 

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the aluminum interior, negative.

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Second, a very bright halogen lamp scans the image.

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Black areas don't reflect the light, 
but white non-image areas do. 

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When the light strikes the drum 

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the silica surface becomes conductive and 

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charge flows away leaving only a charged image.

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Third, the maching wipes toner across the drum.

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Toner isn't ink; it's tiny particles 
made of plastic and carbon.

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Because it has a negative charge the toner sticks 
only to the positive image on the drum.

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Fourth, the wire charges a piece of paper 

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so it can attract the toner from the drum.

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Fifth and finally, a heater in the copier 
melts the plastic in the toner 

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to fuse the image to the paper.

41
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Come in!

42
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Becky says you took the photocopier?

43
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*again*?

44
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I'm, uh, I'm repairing it...

45
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Well, so how does it work?

46
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So, the drum goes down underneath here

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and then there's a light that scans across the top.

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and then the toner... [click]