| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for automatically focusing an endoscope capable of quickly focusing. SOLUTION: An auto-focusing endoscope comprises an objective optical system for varying power and focusing by moving a movable varying power element to a light axis direction while approaching to an observed object, and for shifting from a distal observation state to a proximal observation state; a driving means for moving the movable varying power element; a contrast detecting means for detecting contrast from an image of the observed object arrived at an object distance detecting means for detecting an object distance from the objective lens system to the observed object or at an imaging device; and a control part for controlling the driving means, base on the object distance information or contrast information. In the method, when X (of which the value is 0 at the time of the distal observation) represents a driving amount of the driving means; D<SB>0</SB>represents the object distance to the observed object; a formula D<SB>0</SB>=f(X) is established, and under the condition of X<SB>t</SB>/2≤X≤X<SB>t</SB>, following condition formula (1) is satisfied: 0.05<[f(X-X<SB>t</SB>/10)-f(X)]/D<SB>ot</SB><0.5, wherein, D<SB>ot</SB>is the object distance to the observed object in the proximal observation; X<SB>t</SB>is the driving amount of the driving means from a distant observation point (0≤X≤X<SB>t</SB>). COPYRIGHT: (C)2004,JPO |
