An active type display panel comprises a plurality of pixel sections each having a series circuit constituted by a light emitting element and a drive element for supplying a drive current to the light emitting element, a pair of power supply lines which connect the series circuits of the pixel sections in parallel, and a plurality of measurement lines. Inside the tank a mixing device suitable to perform the continuous circulation of the product inside the tank and a cooling device for cooling the product are arranged. In one embodiment, the receiver is determined to have lost synchronization with the transmitter if two or more of the three synchronization indicators indicate a loss of synchronization.