Acer S2W 3300U Service Manual - Page 14

(3) Imaging It gets an image by lens in this step, and the diagram is shown in Fig.4-4. The light of the object passing through this lens to form an image on the CCD, and the magnification(M) equals image distance (q) divided by object distance (p), i.e. , M= q / p. From Fig.4-4 ,we can get the paraxial formula about lens focus(f), object distance(p) and image distance(q). The formula describes relation between lens focus(f), object distance(p), and image distance(q) as 1/f = 1/p +1/q. f IMAGE OBJECT q p Figure 4-4 The Optic's Relation Note: A hex screw in the lens box as shown in Fig.4-5 fixes the lens. If you loosen the hex screw, then you can adjust the lens, and the object distance is changed. When the object distance is changed, the image distance changes according to the formula. At this moment, the image can not accurately form on the CCD, and the quality and resolution of scanner will be influenced. In order to keep high quality and resolution of the scanner, never try to loosen the hex screw and adjust the lens position.