# US 10,369,728 B2 · Optical element and method for manufacturing optical element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,369,728 B2 - Document ID: US10369728B2 - Status: Granted - Kind: B2 - Application number: 14/776,303 - Filed: 2014-01-15 - Published: 2016-02-11 - Granted: 2019-08-06 - Earliest claimed: 2013-03-21 - Assignees: Konica Minolta, Inc. - Applicants: Konica Minolta, Inc. - Inventors: Takehiko Goshima; Yoshihiro Okumura; Hiroshi Umetsu; Seiji Yuasa - Web page: https://patentgrep.com/patent/US10369728B2 ## CPC - B29C 45/0025: {Preventing defects on the moulded article, e.g. weld lines, shrinkage marks (preventing defects on the preformed parts or layers B29C45/14836)} - B29C 45/372: {provided with means for marking or patterning, e.g. numbering articles} - B29D 11/00644: {polarizing} - G02B 1/04: made of organic materials, e.g. plastics (G02B1/08 takes precedence) - G02B 3/00: Simple or compound lenses - B29C 45/2756: {Cold runner channels} - B29K 2101/12: Thermoplastic materials - B29K 2995/0013: Conductive - B29K 2995/0072: Roughness, e.g. anti-slip - B29L 2011/00: Optical elements, e.g. lenses, prisms - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES ## Abstract To provide a method for manufacturing an optical element, which improves the surface precision of the optical surface as well as reducing the birefringence at a low cost. A method for manufacturing an optical element 1090A having optical surfaces 1091 and 1092 and a non-optical surface 1093A that is adjacent to the optical surface 1092 via a ridge by injection molding includes forming the non-optical surface 1093A with a mold surface. The mold surface includes a sink forming area 1095 as a first area having a first surface roughness, and a high transfer area 1094 as a second area having a second surface roughness different from the first surface roughness. The second area is located outside the first area. ## Claims ### Claim 1 A method for manufacturing an optical element having an optical surface and a non-optical surface that is adjacent to the optical surface via a ridge by injection molding, the method comprising: forming the non-optical surface with a mold having a surface that includes a first area having a first surface roughness for forming a sink area, and a second area having a second surface roughness larger than the first surface roughness, the first area having a short side and a long side, the second area having a short side and a long side, and the second area being located between the first area and the optical surface, wherein a length of the long side of the first area is the same as a length of the long side of the second area and the long side of the first area is in contact with the long side of the second area in its entirety. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first surface roughness of the first area is not less than Ra 0.1 nm and less than Ra 0.5 μm, and the second surface roughness of the second area is not less than Ra 0.5 μm and not more than Ra 100 μm. ### Claim 3 (depends on 1) The method according to claim 1, wherein difference between the first surface roughness of the first area and the second surface roughness of the second area is not less than Ra 0.3 μm and less than Ra 100 μm. ### Claim 4 (depends on 1) The method according to claim 1, wherein a surface of the mold where the first area is formed is made of a material having a first thermal conductivity, and a surface of the mold where the second area is formed is made of a material having a second thermal conductivity higher than the first thermal conductivity. ### Claim 5 (depends on 4) The method according to claim 4, wherein the first thermal conductivity is not less than 0.6 W/m·K and not more than 20 W/m·K, and the second thermal conductivity is not less than 8 W/m·K and not more than 200 W/m·K. ### Claim 6 (depends on 1) The method according to claim 1, wherein the second area is located adjacent to a surface of the mold where the optical surface is formed. ### Claim 7 (depends on 1) The method according to claim 1, wherein a ratio of a width of the second area to a distance between optical surfaces adjacent to the non-optical surface is 15 to 60%. ### Claim 8 A method for manufacturing an optical element having an optical surface and a non-optical surface that is adjacent to the optical surface via a ridge by injection molding, the method comprising: forming the non-optical surface with a mold having a surface that includes a first area having a first surface roughness for forming a sink area, and a second area having a second surface roughness larger than the first surface roughness, the second area being located between the first area and the optical surface, wherein the first area is surrounded by the second area and an entire perimeter of the first area contacts the second area. ### Claim 9 (depends on 8) The method according to claim 8, wherein the first surface roughness of the first area is not less than Ra 0.1 nm and less than Ra 0.5 μm, and the second surface roughness of the second area is not less than Ra 0.5 μm and not more than Ra 100 μm. ### Claim 10 (depends on 8) The method according to claim 8, wherein difference between the first surface roughness of the first area and the second surface roughness of the second area is not less than Ra 0.3 μm and less than Ra 100 μm. ### Claim 11 (depends on 8) The method according to claim 8, wherein a surface of the mold where the first area is formed is made of a material having a first thermal conductivity, and a surface of the mold where the second area is formed is made of a material having a second thermal conductivity higher than the first thermal conductivity. ### Claim 12 (depends on 11) The method according to claim 11, wherein the first thermal conductivity is not less than 0.6 W/m·K and not more than 20 W/m·K, and the second thermal conductivity is not less than 8 W/m·K and not more than 200 W/m·K. ### Claim 13 (depends on 8) The method according to claim 8, wherein the second area is located adjacent to a surface of the mold where the optical surface is formed. ### Claim 14 (depends on 8) The method according to claim 8, wherein a ratio of a width of the second area to a distance between optical surfaces adjacent to the non-optical surface is 15 to 60%.