| 摘要 |
PURPOSE:To reduce power consumption to drive a light emitting element and to shorten a time necessary to re-communicate at the occurrence of error by providing a discrimination circuit to drive the light emitting element power source in a data transmission requesting side block. CONSTITUTION:The discrimination circuit 10 to drive the light emitting element power source in a data transmission requesting side block. The light emitting elements 4 and 5 of the respective blocks in a ceiling side transmitter/receiver unit are not of continuous driving system. But instead, the light emitting element power source in the level data-transmission requesting side block is driven based on the level detection value from a light received phase comparator that compares the phases of infrared rays of the data transmission requesting side block and the opposite block, and the 1ight emitting element power source of other blocks are stopped, in order to reduce the power consumption. Also, if a re-communication is necessary due to a defective data, only the block pertinent to the re-communication is drive, and thus the time necessary for the communication is shortened. |
