PURPOSE: To make gravitational flexion extremely small, to reduce a shift in best focal position and to realize superior resolving performance by holding a lens rod group with holding members made of materials with high flexural rigidity.
CONSTITUTION: Both flanks of the lens rod group 20 of a rod type lens assembly 23 are adhered and held with a couple of thin plate type holding members made of materials with high flexural rigidity such as aluminum, and supplementary members 22 are adhered between projection parts 21' respectively. Consequently, the lengthwise flexural rigidity of the assembly 23 is high and the maximum flexion due to own weight becomes extremely small. Therefore, a shift in the best focal point is reduced when this assembly is used for a copying machine and the resolving performance of a copy image is improved.
YAMAMOTO TSUTOMU
MIURA TSUTOMU
