원문 게시자: mayer ,
When a optical drives lens starts getting dirty it harder to read disks. The data on a CD is four times the size of a DVD. (imagine trying to read this print if it was four times smaller). The track pitch on a DVD is 2.16 times smaller, and the minimum pit length for a single-layer DVD is 2.08 times smaller than on a CD. By multiplying these two numbers, we find that there is room for about 4.5 times as many pits on a DVD. So CDs may still work OK on a machine but it may not be able to read the smaller DVD data.