Patent ID: 8395846

Claim:
A lens system for projecting projected light onto a display medium, comprising in order from a side of display medium: a first lens that is a meniscus-type lens with negative refractive power and includes a convex surface on the side of display medium; a second lens that is a meniscus-type lens with positive refractive power and includes a concave surface on the side of display medium; a third lens that is a meniscus-type lens with positive refractive power and includes a concave surface on the side of display medium, an effective diameter of the concave surface being larger than an effective diameter of the concave surface of the second lens; and a fourth lens that is a meniscus-type cemented lens with positive refractive power and includes a concave surface on the side of display medium, an effective diameter of the concave surface being larger than the effective diameter of the concave surface of the third lens and at least part of the concave surface and at least part of a convex surface of the third lens are located in a shared space along an optical axis.