Patent ID: 8345139

Claim:
An eyepiece lens comprising, arranged along an optical axis thereof and in order from an image display surface side towards an observer side: a positive first lens in which a surface on the image display surface side has a refractive power stronger than the refractive power of a surface on the observer side; a negative second lens having a meniscus shape, a surface of the negative second lens on the image display surface side having a convex shape; and a positive third lens, both surfaces of which have a convex shape, wherein, during diopter adjustment, the first through the third lenses move along the optical axis, and wherein a focal length (f) of the entire eyepiece lens and a diagonal length (H) of the image display surface satisfy the following conditions: 0.45 <H/f< 0.70 21.0 (mm)< f< 29.0 (mm).