| 摘要 |
PURPOSE:To reduce pattern noise by forming longitudinal row block groups by peripheral groove and lateral groove, dividing them into a plural number of longitudinal row blocks per the predetermined pitch in the peripheral direction and forming a knotch in the peripheral direction in each block in such a way that the number of block groups having large pitch is larger than the number of block groups having small pitch. CONSTITUTION:Longitudinal block groups 5 to 5 per two rows are formed on both sides of central peripheral line 0 by peripheral grooves 1a, 1b, a central peripheral groove 2, and lateral grooves 3a, 3b, 4a, 4b. Further, each longitudinal block group 5 to 6 is arranged, for example, at a combination of the length in peripheral direction of each block 5a to 5c, 6a to 6c which includes adjacent lateral grooves 3a, 3b on one side and a plural number of pitch length P1 to P3. And, in each block 5a to 5c, 6a to 6c, the number of block groups which are parallel with the lateral grooves 3a to 4b and have long pitch is large to form a knotch 9. That is, they are provided in such a way that pitch P1 is one, pitch P2 is two, and pitch P3 is three in the illustration. |
