Most scanners do need their own independent power source in order to operate correctly. Different types of scanners will require different power sources depending on the type of scanner and its function.
Desktop scanners will generally require a wall outlet for electrical power, while some may also be powered via a USB cable. If the scanner is not powered by either a wall outlet or USB cable, then it may come with an AC adapter that requires a separate power cable connection.
Portable and handheld scanners typically require AA or AAA batteries to provide power, while some wireless scanners may come equipped with a rechargeable battery.
Flatbed scanners will usually require a wall outlet for power, while some may also feature a USB connection that can be used to power the scanner. Some flatbed scanners may also feature an internal battery, allowing them to operate without a power cord.
Photo scanners generally require a wall outlet for power, although some models may offer an optional battery pack that can be used to power the device.
Document scanners usually require a wall outlet for power, but may also include a USB or AC adapter that can be used to power the device. Some document scanners may also have an internal battery, allowing them to operate without a power cord.
Overall, most scanners will require some sort of independent power source in order to function correctly. Depending on the type and function of the scanner, this power source could be a wall outlet, USB port, battery, or AC adapter.