What is an 'encoder strip' and how could it cause a 15-blink error on a Canon iP2770?

The encoder strip is a thin, clear plastic strip with fine lines that runs across the printer carriage. It helps the printer determine the precise position of the print head. If it's dirty, smudged, or damaged, the printer's sensors can't accurately track the carriage, leading to errors like the 15 blinks, often misdiagnosed as a print head issue.