A dead bolt lock apparatus specifically adapted for use with a flight deck door of an aircraft. Further, a light-emitting element having good chromaticity is disclosed. As a result, asynchronous notifications are selectively generated in association with the performance of partition management operations based upon indications in the requests made by partitions for such operations. Since the image data is transmitted from the printer controller to the printer at the fixed period, printing can be performed at a constant speed without requiring that the printer be provided with an image memory for storing image data representing one frame of an image.