| 摘要 |
<p>PURPOSE:To uniformize the width of finish patterns by allowing the light from a light source via a slit provided on a light shielding plate to pass through an original film and a photosensitive film and adjusting the intensity of the light source according to the quantity of transmitted light. CONSTITUTION:The original film 32 and the photosensitive film 31 are brought into vacuum contact with the surface of a glass plate 30 and are disposed on a light source part 10. The light source part 10 consists of the light source 11 and the light shielding plate 12. The light shielding plate 12 is provided with a slit 13 having a prescribed area. The light quantity which a photosensor 33 receives decreases upon increase of the pattern density if the original film 32 is a positive film. A light quantity adjusting circuit 34, therefore, acts to increase the light quantity from the light source 11 by receiving the change thereof. The negative image of the pattern width finer as the pattern density is higher is eventually drawn on the photosensitive film 31. The pattern width finished on a printed circuit board is uniformed in this way.</p> |
