| 摘要 |
PROBLEM TO BE SOLVED: To obtain a satisfactory image even at a large and oblique projection angle by arranging a magnifying side image plane and a reducing side image plane roughly in parallel with each other and allowing a projection lens system to have the image plane bending characteristic bended in a projected shape toward the projection lens system in a magnifying side. SOLUTION: A magnifying side image plane and a reducing side image plane are arranged in parallel with each other and a projection lens system has the image plane bending characteristic bended in a projected shape toward the projection lens system in a magnifying side. Moreover, the magnifying side image plane and the reducing side image plane are arranged roughly in parallel with each other and satisfy 20<=θ<90 and conditions of an equation ofΣi (1/ri)(1/ni-1/n'i)}>0.25/L. In the equation,θexpresses the angle formed by a straight line connecting the center of the diaphragm of the projection system and the center of the magnifying side image plane and the normal of the magnifying side image plane, ri expresses the radius of curvature of i-th refraction surface to be include in the projection lens system, ni expresses the refractive index of the medium being more near to an object side than the i-th refractive surface to be include in the lens system, n'i expresses refractive index of the medium being more near to the image side than the i-th refractive surface to be include in the lens system and L expresses the disatance between the center of the magnifying image plane and the center of the diaphragm of the lens sytem.
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