| 摘要 |
PURPOSE:To shorten the overall length of a copying device by composing each of projection lens systems, provided in parallel and at right angles to optical axes so that the distance between optical axes is nearly an integral submultiple of each image circle diameter, of a front and a rear lens group. CONSTITUTION:An erected-image projection system consists of a plastic plate 7 made of a lensI-1, etc., molded in one body, a plastic plate 8 made of a lensI-2, etc., molded in one body, and similar plastic plates 9 and 10. Four lensesI-1,I-2, II-1, and II-2 shown by slanting lines from one projection lens system. Then, the front lens groupIforms an inverted intermediate image of an object, and the rear lens group projects the intermediate image on a projection surface as an erected image; luminous intensity distribution on the projection surface decreases uniformly centering on the axis, and equalityIholds. In the inequalityI, f1 is the focal length of the front lens groupI, and F is that of the projection lens group defined by expression II where the focal length of the rear lens group II is f2 and the distance between the rear principal point of the front lens groupIand the front one of the rear lens groups II is l. |
