The Brother DS-640 is a mobile scanner that can be used to scan individual sheets of paper and ID cards.
Scan using Brother iPrint&Scan: The iPrint&Scan is available for installation during the driver install. Once the app is open, choose Select your machine at the bottom-right and select the scanner. The rest of the scanning process is similar as any normal scanning using this software.
Scan options: For a small sheet scanned at 300x300 DPI, I found different levels of PDF/A filesizes when I tried the 4 different scanning options in iPrint&Scan:
Black & White (51 KB),
Gray (Error Diffusion) (130 KB),
True Gray (235 KB) and
24bit Color (265 KB).
Calibration: Insert the Calibration sheet that came with the scanner face up into the scanner. Open the Brother Utilities application and choose the scanner from the dropdown list at the top-left corner. Choose Tools -> Remote Setup -> Machine Info. Choose Start for the Calibration. The scanner will ingest the calibration sheet and calibrate itself.
Linux: This scanner would not be recognized in Ubuntu 22.04 until I downloaded its Linux installer from its support page. I installed and checked that using these commands:
$ sudo dpkg -i --force-all brscan5-1.3.0-0.amd64.deb $ dpkg -l | grep Brother
However, I had to restart the computer for the scanner to be detected. After that it appeared in apps like Simple Scan and I could scan.