Image Number 10 for United States Patent #5861825.
5*3 states are arranged on a plane composed of the horizontal axis and vertical axis, 2-bit data of 01, 10, 00, and 11 are assigned to the state transitions in the up, down, right, and left-directions respectively in the 3*5 states. A 20-bit code is generated by 10 times the state transitions. 2.sup.16 20-bit codes are prepared and these codes have a one-to-one correspondence to 16-bit data (2.sup.16). The end point of the previous state transition is the starting point of the next state transition, and 16-bit data are converted successively to 20-bit codes while the state transitions occur continuously. In the manner as described above, the conversion efficiency in PR (1, 1) is improved.