How does a printers know how much ink is left in thier catridges?

i know how to check the level of printer ink catridge on the computer. im just wondering how the printer knows how much is left?How does a printers know how much ink is left in thier catridges?
This Depends Largely On The Printer. MOST Use The Known Amount Of Ink In A New Cartridge And Simply Keep Track Of How Much Output Is Done. (How Many Pages X Size X Colors X % Coverage) Not Always Accurate, But Close Enough. They Want You To Buy LOTS Of Ink Anyway. SOME Use A Visual Method With A Special Light Shining Through The Cartridge To A Sensor. And Some Use Other Methods.How does a printers know how much ink is left in thier catridges?
It does not


Only when the printer stops printing do we come to know that the ink in the print cartridge is over.
They measure the cat first and if it fits in the ridge, you got enuf to right a litter.
Different manufacturer uses different techniques.In some ink jet printers there is a sensor PCB in the cartridges.It counts the nos of drops of the ink.In ink jet printers one bubble is formed.so it is easy to count.In some ink jet(like brother) there is no such PCB in the cartridges.bat the cartridge is made of transparent plastic and it is placed between one sensor.as the ink reduces the sensor sences the level through the transparent plastic body.


In case of laser printers,some printers don't have such system to show that is is empty.when the printing becomes very light one can understand that there is no more toner(ink)in the cartridge(toner module).But in some laser printer there is a sensor PCB behind the toner cartridge.some times it sences through the level of the toner and sometimes it tracks the amount of toner used in each printing.