| 摘要 |
<p>PURPOSE:To provide an exposure control function and to prepare a spot pattern by a simple method without regulating the quantity of light according to the thickness of a ruled line and without regulating a width or providing a filter, by spirally arranging light impervious or pervious windows in a predetermined circular region. CONSTITUTION:A spot pattern 41 is constituted by spirally arranging a large number of dots 42 as light pervious windows. In a spiral case, when a spiral is cut at the angles equal from the center, the cut segments become long toward the outer periphery. Therefore, when the pitch P between the dots is fixed, the dots are not radially overlapped, and the inside dots and outside dots are arranged so that the positions thereof are slightly shifted. When this pattern 41 is irradiated with light, the light passes from the light pervious dot parts and the number of the obtained light spots correspond to the number of the dots. Therefore, when the dots are spirally distributed with respect to the number and size corresponding to the diameter of a circle, exposure amount can be kept constant regardless of the thickness of the ruled line.</p> |
