Got a large LCD display having only 2 wires (power and gnd) from digital scales

I noticed on bathroom digital scale there's a very large blue LCD display used. When I opened the assembly, there were only 2 wires connected to the display. Red wire and Black wire. Just to test, I put +5v on red and gnd on black wires and it lit the display.

I am wondering how this one will be working and displaying digits?

Any ideas?