Something is bugging me. Please help.

[BillyCarpenter]

Let me say this upfront. This information is only to satisfy my curiosity. It's not a necessity to repair a copier but I'd like to know. Back in the day, I started in the business working for a Sharp dealer. That's where I was taught the basic copy process (analog) and later the digital copy process. I clearly remember one of the main differences being that the polarity for the drum and DV voltage was opposite from the analog machines. That's been a long time ago and it's foggy in my mind.


Anyway, when I started training the new guy, I wanted to be accurate when describing the copy process and include the correct drum and DV charge voltage. You may want to call it "bias" voltage but you know what I'm talking about.

Anyway, nowhere in the manual can I find any information of this. Oh, I can find what board produces the voltages to the mag roller and PCR and the control signals for each but that's about it.

I'd like to know is the mag and PCR voltage negative or positive? And what are these voltages?

Lastly, what is the polarity of the developer? (If the dv has a positive polarity, then the toner will have a negative polarity. Correct?)


Do they still teach any of this or no?

[bsm2]

Kyocera services manuel will go into detail on the copy process. Kyocera usually hides the voltages in specification page or not listed at all.

Most of the settings are DFW do not F with and are digital.

[copier addict]

Both the drum and the dev carry the same charge to start. Usually between -600 and -700 volts. The printhead then writes the image on the drum, thus causing the image portion of the charged drum to carry a different voltage. The charged toner is then attracted to the portion of the drum with the different charge.

[bsm2]

OmG

[BillyCarpenter]

Both the drum and the dev carry the same charge to start. Usually between -600 and -700 volts. The printhead then writes the image on the drum, thus causing the image portion of the charged drum to carry a different voltage. The charged toner is then attracted to the portion of the drum with the different charge.

Hhhmm....

I think the voltage is negative but there's no printhead. There's a laser and it writes a latent image on the drum that is less negative (the voltage isn't positive, it's just more positive where the laser hits on the drum) thus the toner is transferred only to the part of the drum that the laser touched.

I know the complete theory of how it works, I simply need the voltages and the polarity.

[BillyCarpenter]

By the way, I'm pretty sure the voltages change as more pages accumulate on the DV's and DR's. The voltages increase via calibration to compensate for wear & tear. Same with laser intensity and exposure lamp. Correct me if I'm wrong.

[copier addict]

Hhhmm....

I think the voltage is negative but there's no printhead. There's a laser and it writes a latent image on the drum that is less negative (the voltage isn't positive, it's just more positive where the laser hits on the drum) thus the toner is transferred only to the part of the drum that the laser touched.

I know the complete theory of how it works, I simply need the voltages and the polarity.

Printhead, laser, write unit, LSU, same thing.

[PrintWhisperer]

I think the best way of thinking about it is to leave polarity out of it. It really doesn't matter.

Best to think of the drum surface and 'Charged' or 'Discharged'.

For Kyocera Charged areas repel toner. Drums are uniformly charged until hit (written) with light (LSU) causing them to discharge (Ground potential=0) creating the latent image (latent as in unseen and consisting of differing charged areas)

Discharged areas attract toner, hence the phrase 'Write to Black'

This whole positive/negative perspective can change with manufacturers technology. You could use opposite charged toner and 'write to white' instead, which is how analog machines worked.

As for DV, it is usually an AC bias which fluctuates between being 'more positive and less positive' compared to the drum potential in order to have a 'push/pull' effect where the actual 'duty cycle' pushing toner is determined by offsetting the 0 point of the AC sine wave with an additional DC bias (slice level)

That's an early days Canon description but it still applies.

[BillyCarpenter]

Printhead, laser, write unit, LSU, same thing.

Wasn't trying to nitpik. I just never heard a laser called a printhead.

[BillyCarpenter]

I think the best way of thinking about it is to leave polarity out of it. It really doesn't matter.

Best to think of the drum surface and 'Charged' or 'Discharged'.

For Kyocera Charged areas repel toner. Drums are uniformly charged until hit (written) with light (LSU) causing them to discharge (Ground potential=0) creating the latent image (latent as in unseen and consisting of differing charged areas)

Discharged areas attract toner, hence the phrase 'Write to Black'

This whole positive/negative perspective can change with manufacturers technology. You could use opposite charged toner and 'write to white' instead, which is how analog machines worked.

As for DV, it is usually an AC bias which fluctuates between being 'more positive and less positive' compared to the drum potential in order to have a 'push/pull' effect where the actual 'duty cycle' pushing toner is determined by offsetting the 0 point of the AC sine wave with an additional DC bias (slice level)

That's an early days Canon description but it still applies.

That pretty much answers my question. I need to know these things.