How does a HP printer know cartridges are aligned?

[Skyzoomer]

I have a HP Photosmart D5360 inkjet printer. It uses two ink cartridges that have the print heads built into each cartridge. Left cartridge is tri-color, right cartridge can either be all back or a photo cartridge. (The photo cartridge has light cyan, light magenta and black.)

When I replace a cartridge, the printer does a cartridge alignment procedure to align the printout from the two cartridges. The cartridge alignment procedure can say whether the alignment was successful or whether it failed.

Does anyone know how HP printers that have the print heads in the cartridges can determine whether the cartridge alignment procedure was successful? Does it have a built-in camera that looks at the print out to determine alignment?

Thanks,
Skyzoomer

 

[Techie14]

Sounds interesting.
Not sure but did it actually happen to you that your printer automatically detected a misalignment? Or is it maybe only some kind of fake function?
From my experience you always get a specific print out that you put back into the scanner. But since your device doesn't have any scan function...

 

[christian1990]

maybe laser

 

[Batmeat]

My understanding is that they don't. The cartridges have a circuit in them that comes in contact with the printer. Once that connection is interrupted (like changing out a cartridge) the printer recognizes this as a cartridge change and therefore needs to re-align the heads. Head alignment is based on contact with the nozzle that ejects ink from the cartridge.

I could be wrong, but that's how I've always understood it.

 

[Juventas]

The carriage has a CMOS sensor (i.e. a cheap camera). When it prints the alignment page, it scans it immediately after, and detects the marks on the page in order to align itself.

If you look inside the printer when its printing an alignment page, you can see the LED that is illuminating the page for the sensor. Very similar to optical mouse technology.