A light emitting device comprises a gallium oxide based substrate, a gallium oxynitride based layer on the gallium oxide based substrate, a first conductivity-type semiconductor layer on the gallium oxynitride based layer, an active layer on the first conductivity-type semiconductor layer, and a second conductivity-type semiconductor layer on the active layer. When the user approaches, a sensing unit senses the situation, controls the pivot motor to lower down the seat and controls the rolling motor to replace the covering film. The drain and gate of the switch transistor can be electrically connected to the drain and gate of the replica transistor, respectively. A correction processing unit offset-corrects the image data by using first offset data corresponding to the selected imaging time and outputs first image data. Since the P2P environment also allows for the existence of multiple separate groups of peers within the P2P cloud, a preferred embodiment of the present invention also allows for the enumeration of all groups associated with a given identity, for each identity existing for the user. during the step of ejecting the droplets of the ink.