PURPOSE: To quicken a device by providing a data expansion part and a storage part, inputting old expansion data outputted from the storage part, synchronizing the old expansion data with a period τ and separating and outputting original data by (n) pieces.

CONSTITUTION: The data D1 inputted at every transfer period τ are collected by four pieces in the period T of four times in the data expansion part and converted to the expansion data D2. After the old expansion data is read by the storage part 2, the expansion data D3 read from the storage part 2 storing the new data D2 from the expansion part 1 is inputted to a data compression part 3 and the data 3 is separated to original (k) pieces of data and synchronized with the period τ and outputted successively from the old data and the output data D4 is inputted to a delay part 4. The data D4 transferred at every period τ is shifted by the delay part 4. That is, after the data D1 of the period τis converted to the data of the period T of (k) times, the storage part 2 shift- operates essentially.