| 摘要 |
PURPOSE: To reduce a noise by forming a pattern out of pattern constitution unit rows containing a pattern constitution unit in each cell along horizontal and vertical axes, with the units arrayed at the prescribed pitch in the order of length skipping one or more adjacent pitches. CONSTITUTION: A tread pattern is made of pattern constitution units having a different number of types S with a pitch P equal to or above three, and the definition zone of a chaos function fc expressed as X(n+1)=fc(Xn) is determined as the summation of all vertically arranged zones for each cell along a horizontal axis, provided that the horizontal axis is expressed as Xn and a vertical axis as X(n+1). In other words, zones having a pitch ratio equal to or less than 1.5 is selected, provided that a small pitch assigned to each cell in vertical and horizontal directions is used as a denominator and a large pitch as a numerator, and the summation of the zones is used as a definition zone. Also, the pitch P has a calibrated pattern constitution unit row obtained from the calibration of a pattern constitution unit rows including pattern constitution units so laid as to skip one or more adjacent pitches arranged in the order of pitch length along peripheral direction via the conversion of a sequence obtainable from the function fc. According to this construction, a noise can be lowered and uniformity can be improved. |
