Question

how do scanner and other reading device work

Answer 1

Scanners operate by shining light at the object or document being digitized and directing the reflected light (usually through a series of mirrors and lenses) onto a photosensitive element. In most scanners, the sensing medium is an electronic, light-sensing integrated circuit known as a charged coupled device (CCD).

Answer 2

A scanner works by collecting light using charged couples devices which convert the light into electronic signals that are sent to the computer.