An electronic device is described. The device includes a substrate for a luminescence panel that includes data lines and pixels in which a luminescence element can be formed. Each pixel includes a driving transistor that converts a signal voltage from a data line into a signal current, and a first switch between the data line and the gate of the driving transistor. The device includes a first circuit to flow a test current from the data line through the driving transistor, a second circuit to generate a voltage on the data line corresponding to a gate voltage on the driving transistor generated by the test current, and a voltage detector to detect the voltage in the data line.