An initial positive trigger value is above a minimum positive trigger value which is above an input signal DC component value. Then, a gate insulating layer, an active layer and a data metal are sequentially formed on the base substrate to cover the gate part. In a learning control interval from the issuance of a learning control start command to the issuance of a learning control end command, the input and output are turned on so that the learning control is performed to input the position deviation and create and output the correction data. A collar with a transparent closed end is inserted into an opening in the housing.