Lens and method of molding lens

Patent metadata

Field	Value
Publication number	US-8964314-B2
Application number	US-201414228786-A
Country	US
Kind code	B2
Filing date	Mar 28, 2014
Priority date	Sep 30, 2011
Publication date	Feb 24, 2015
Grant date	Feb 24, 2015

Abstract

There are provided a lens that is molded with high accuracy and a method of molding the lens. The lens has an optical axis and includes a pair of optical functional surfaces on front and rear surfaces thereof. The lens includes an optical functional portion that includes the pair of optical functional surfaces, an edge portion that is provided at an outer periphery of the optical functional portion, and a connecting portion that is provided between the optical functional portion and the edge portion, connects the optical functional portion with the edge portion, and is thinner than the edge portion in a direction of the optical axis.

First claim

What is claimed is:

1. A lens that has an optical axis and includes a pair of optical functional surfaces on front and rear surfaces thereof, the lens comprising:
an optical functional portion that includes the pair of optical functional surfaces;
an edge portion that is provided at an outer periphery of the optical functional portion; and
a connecting portion that is provided between the optical functional portion and the edge portion, connects the optical functional portion with the edge portion, and is thinner than the edge portion in a direction of the optical axis,
wherein the optical functional portion, the edge portion, and the connecting portion form a first molded portion that is formed by compression molding and includes the optical functional portion, the connecting portion, and a part of the edge portion, and a second molded portion that is formed by injection molding and forms the rest of the edge portion, and
the thickness of a boundary surface between the first and second molded portions in the direction of the optical axis is larger than the thickness of the thinnest portion of the connecting portion in the direction of the optical axis,
wherein a refractive index of the first molded portion, denoted by n1, and a refractive index of the second molded portion, denoted by n2, satisfy “1<n1<n2”.

2. The lens according to claim 1 ,
wherein the second molded portion is made of a material that has an internal transmittance of 30% or more per a thickness of 1 mm.

3. The lens according to claim 1 ,
wherein one or both of the pair of optical functional surfaces are concave surfaces.

4. The lens according to claim 1 ,
wherein one or both of the pair of optical functional surfaces are convex surfaces.

5. A lens mold for molding the lens according to claim 1 , the mold comprising:
a gas vent hole or a gas vent groove that is formed at an outer peripheral transfer cavity portion.

6. The lens mold according to claim 5 ,
wherein the gas vent groove or the gas vent groove is a gap between a core part and a body part of the lens mold.

7. The lens according to claim 1 ,
wherein when the dimension of the lens in the direction of the optical axis is the thickness of the lens, the thickness of the thinnest portion of the lens is included in the first molded portion.

8. The lens according to claim 7 ,
wherein one or both of the pair of optical functional surfaces are convex surfaces.

9. The lens according to claim 7 ,
wherein one or both of the pair of optical functional surfaces are concave surfaces.

10. The lens according to claim 7 ,
wherein the second molded portion is made of a material that has an internal transmittance of 30% or more per a thickness of 1 mm.

11. The lens according to claim 7 ,
wherein the thickness of the thinnest portion is in the range of 0.1 mm to 1.0 mm.

12. The lens according to claim 11 ,
wherein one or both of the pair of optical functional surfaces are convex surfaces.

13. The lens according to claim 11 ,
wherein one or both of the pair of optical functional surfaces are concave surfaces.

14. The lens according to claim 11 ,
wherein the second molded portion is made of a material that has an internal transmittance of 30% or more per a thickness of 1 mm.

15. A method of molding a lens according to claim 1 , which includes a pair of optical functional surfaces on front and rear surfaces thereof, by a mold, the mold including a first mold that includes a first transfer surface for transferring one of the pair of optical functional surfaces and a first outer peripheral transfer surface formed around the first transfer surface and a second mold that includes a second transfer surface for transferring the other of the pair of optical functional surfaces and a second outer peripheral transfer surface formed around the second transfer surface, the method comprising:
a compression molding step of placing a compression molding material having a refractive index, n1, greater than 1 on the second transfer surface, and forming the pair of optical functional surfaces on the compression molding material by compressing the compression molding material between the first and second transfer surfaces while closing the molds by moving the first and second molds relative to each other so that the first and second molds approach each other; and
an injection molding step of forming outer peripheral portions of the pair of optical functional surfaces with an injection molding material by injecting the injection molding material having a refractive index, n2, higher than the refractive index, n1, of the molding material into an outer peripheral transfer cavity partitioned between the first and second outer peripheral transfer surfaces when the molds are closed,
wherein the outer peripheral transfer cavity is filled with the injection molding material in the injection molding step when at least a part of the compression molding material is extruded into the outer peripheral transfer cavity by the compression molding step.

16. The method of molding a lens according to claim 15 ,
wherein when the dimension of the lens in a direction of an optical axis is the thickness of the lens, the thinnest portion of the lens is molded between the first and second transfer surfaces in the compression molding step.

17. The method of molding a lens according to claim 15 ,
wherein the compression molding material is a thermoplastic resin.

Assignees

• Fujifilm Corp

Inventors

• Koike Kazumi
• Watanabe Seiichi
• Fujiwara Takayuki

Classifications

• B29D11/00413

  made by moulding between two mould parts which are not in direct contact with one another, e.g. comprising a seal between or on the edges (B29D11/00019 - B29D11/00355, B29D11/00423, B29D11/00432 take precedence) · CPC title

• B29C43/021

  characterised by the shape of the surface · CPC title

• B29L2011/0016

  Lenses · CPC title

• B29C69/02

  of moulding techniques only · CPC title

• G02B13/0015 Primary

  characterised by the lens design · CPC title