- Let's talk about the Laser Printing Process.
The laser printing process is broken down
into several steps, let's talk about each of those now.
The first is the processing step.
In the processing step, this actually begins
at the computer that initiates the print job.
The computer will calculate the data
that needs to be printed, and then send
that off to the printer either as an entire print job
or it will spool it one page at a time.
Once it gets to the printer, that data is recalculated
and stored in RAM until it's ready to print,
so that's the processing stage.
It's kind of a pre-stage to the actual printing
that happens in the laser printer.
So there we have the processing stage.
The next step is the charging step.
In the charging step, a negative voltage
is applied to the primary corona wire,
that's a wire that sits on the drum in the printer.
So we'll label this, the primary corona wire
and that negative voltage that is applied to that wire
comes from the high voltage power supply
within the printer, that wire actually presses
against the drum which is often
inside of the toner cartridge.
In fact, a lot of these pieces
are inside the toner cartridge on many laser printers.
So in the charging step, a negative voltage
is applied to the primary corona wire
which then passes through to the drum,
so the drum now has a negative charge
and that is the charging step.
Next on the list is the exposing step.
This is also known as the writing stage.
In the writing step or exposing step,
the laser is activated and it shines its light
on the drum as the drum spins.
What this does is it applies a lesser negative charge
to the drum and that ultimately is gonna be what creates
the letters, those imaged areas, those areas written
by the laser.
And by lesser negative charge, I'm saying,
let's say this particular laser printer
applied a negative charge of -600 volts DC
to the primary corona wire.
Well, when the laser shines on the drum,
that area would be a lesser charge
meaning, perhaps -100 volts DC.
So it's actually a greater number
but it's a lesser negative charge than this.
So, that is the exposing also known as the writing stage.
Next is the developing stage.
In the developing stage,
the toner is applied to the drum and basically what happens
is you have negatively charged toner,
but it's a higher charge than the areas of the drum
that we're written to by the laser.
And so the toner is applied to the areas of the drum
that we're written to, and that is the developing step.
The next step is the transferring step.
In the transferring step,
the toner is going to be transferred over to the paper.
What happens is, the paper now enters the printer itself
and it does this through some entrance rollers
that help guide it in.
So this is our paper here, my dotted line,
and on most laser printers, the paper passes through
between the drum and what's known as
the transfer corona wire,
the transfer corona wire is applied a positive charge
and that's important because the paper presses right up
against it, as opposed to pressing up against the drum.
So your paper's going right against
the transfer corona wire,
so this gets a positive charge
and the paper gets a positive charge.
Now remember, the toner that's on the drum
has a negative charge and when it comes to voltages,
opposites attract, so the toner is applied to the paper
and then it passes on into the next step.
So that is the transferring step.
Next, the paper's gonna go past a static eliminator strip.
You wanna remove the static from the paper
because so much voltage has been applied to it
and if you don't remove that,
the toner could just go flying anywhere.
So this static eliminator strip's gonna remove
that excess voltage from the paper.
Now the next step is the fusing step.
In the fusing step, the toner is compressed onto the paper
with heat, making it somewhat permanent.
So the paper's gonna pass through a fusing assembly
and these are rollers that are gonna press the toner
on there and heat up that paper
to about 400 degrees Fahrenheit.
So in the fusing assembly, that toner becomes permanent
on paper going through the fusing rollers
and a lot of heat is applied to make it permanent.
So that's the fusing step.
The last step is the cleaning step,
this is just cleaning up the printer.
In the cleaning step, you have some excess toner on the drum
and the drum keeps spinning and that's scraped off
by a rubber blade and that just falls into
a little toner receptacle.
Also there's an erasing lamp and that shines a light
on the drum so that it can bring
the drum down to zero volts.
So everything is basically now reset
and the printer is for the next print job.
And that is the cleaning step,
so we have the processing step,
the charging step, the exposing step,
which is also known as writing, the developing step,
the transferring step, which is really important,
that's when the toner is transferred to the paper
because the toner has a negative charge,
the paper has a positive charge
which came from the transfer corona wire,
remember, opposites attract when it comes to voltages,
the fusing step, where we had that 400 degrees
and the pressure of the pressure rollers,
and then finally the cleaning step
where the printer's cleaned up and everything is set anew
for the next print job.
So that's it for the laser printing process.