Low Toner Message - How?

[Jeff Wisnia]

My curious mind wants to learn how my Samsung Desktop Printer (Model
XPRESS-2020W) knows that the toner in its cartridge is getting low,
lights a red indicator on its panel and puts a warning message on my
computer screen when its printing, telling me what percentage of toner
(it thinks?)is left and encouraging me to "Click Here" to order another
cartridge.

A few days ago the message said there was 0% toner left. The printing
was getting a little faint so I whipped out my toner refill kit, melted
a 7/16" hole through the wall of the cartridge with a tool I've had for
years, poured in some toner and snapped a plug into the hole. (The tool
is just a small soldering iron with a piece of 7/16" OD thin wall tubing
for its tip. It melts a nice clean hole through the black plastic
cartridge wall.)

It's printing fine again, but the low toner warning light and the screen
message (0% toner left) still come up.

So, what drives those messages, and why didn't the printer know that I'd
put more toner in the cartridge?

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

[Unknown]

It doesn't know. It only knows when you put a new cartridge into the printer.
Then it calculates the amount of toner left according to the number of pages
you print (it uses average coverage to do that). Many laser printers do it that
way. This information is held either in the printer itself or in the chip on
the cartridge. Unless the chip is replaced the light will continue to blink and
will eventually stay on permanently. I understand that it will not effect the
printer function. After about 5 refills you will need to empty the waste toner.
Tony

[Jeff Wisnia]

Tony wrote:
>
>> Jeff
>> --
>> Jeffry Wisnia
>> (W1BSV + Brass Rat '57 EE)
>> The speed of light is 1.8*10^12 furlongs per fortnight.
> It doesn't know. It only knows when you put a new cartridge into the printer.
> Then it calculates the amount of toner left according to the number of pages
> you print (it uses average coverage to do that). Many laser printers do it that
> way. This information is held either in the printer itself or in the chip on
> the cartridge. Unless the chip is replaced the light will continue to blink and
> will eventually stay on permanently. I understand that it will not effect the
> printer function. After about 5 refills you will need to empty the waste toner.
> Tony
>

Thanks, but how does it know that the cartridge I put in is a "new one"
as opposed to just pulling the existing cartridge out and putting it
back in?

There is a four pole printed circuit "connector" on one end of the
cartridge. Maybe there's a fuse or something inside the cartridge which
gets blown when the printer senses it is seeing a "new" cartridge?

[Bob Eager]

One possibility is a serial number in the cartridge which is read out
each time.

[Unknown]

The cartridge has a chip which contains information. Almost certainly you are
right, or altentaively the printer writes to the chip something that identifies
it as having been inserted in a printer (that would ensure that if the
cartridge is refilled and put into a different printer of the same model then
the printer would know it is an old cartridge).
Tony