PURPOSE: A device for simultaneously sensing the shortage of liquid crystals is provided to easily sense the variation of the liquid crystals by using a balance sensor that measures the weight of a tray for storing the liquid crystals. CONSTITUTION: A tray (10) stores liquid crystals. The liquid crystals are injected into a bonded panel. A balance sensor (20) measures the weight of the tray. The balance sensor is positioned under the tray. A communication device (30) transmits information about the weight of the tray.
