Super-wide angle lens
AssigneeNidec Nissin Corporation
InventorIchiroh Saitoh
Life of this patent
Estimating the term…
Abstract
A super wide angle lens is a super wide angle lens which is of high-resolution and whose size, weight and cost can be reduced. It employs a four-group five-element constitution in which in the order from an object side, a meniscus single lens having a negative power, a single lens having a negative power, a single lens having a positive power, and a cemented lens having a positive power are included. The lenses excluding the meniscus single lens are plastic lenses and seven lens surfaces, that are a third surface, a fourth surface, a fifth surface, a sixth surface, a eighth surface, a ninth surface and a tenth surface, are aspheric.
Claims6
A super-wide angle lens comprising:
- a four-group, five-element constitution which includes one cemented lens composed of two lens elements, wherein
- at least four of the five lens elements are plastic lenses,
- two of the plastic lenses are cemented to form the cemented lens,
- at least six lens faces of the four plastic lenses are aspherical surfaces, and
- one of the aspherical surfaces is formed on a cemented surface of the cemented lens, and wherein
- following conditional expressions (a) through (e) are satisfied.
- |Xθ/Ro|≧1.13 (a)
- |(θ/2)/Ro|≧1.59 (b)
- |(θ/2)/Xθ|≦1.41 (c)
- f≦1.1 (d)
- α≧180° (e)
- where
- θ:
- Effective diameter of the cemented surface
- Xθ:
- Aspherical surface amount at the effective diameter “θ” of the cemented surface
- Ro:
- Center curvature radius in the cemented surface
- f:
- Focal length of the super-wide angle lens, and
- α:
- Horizontal angle of view of the super-wide angle lens.
Dependencies are inferred from the claim text.