WO2018025844A1 - Matériau de verre formant une presse et procédé de production d'un élément optique utilisant ledit matériau de verre formant une presse - Google Patents

Matériau de verre formant une presse et procédé de production d'un élément optique utilisant ledit matériau de verre formant une presse Download PDF

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Publication number
WO2018025844A1
WO2018025844A1 PCT/JP2017/027844 JP2017027844W WO2018025844A1 WO 2018025844 A1 WO2018025844 A1 WO 2018025844A1 JP 2017027844 W JP2017027844 W JP 2017027844W WO 2018025844 A1 WO2018025844 A1 WO 2018025844A1
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WIPO (PCT)
Prior art keywords
glass material
radius
curvature
press molding
press
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Application number
PCT/JP2017/027844
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English (en)
Japanese (ja)
Inventor
謙吾 中村
義包 新熊
Original Assignee
Hoya株式会社
謙吾 中村
義包 新熊
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Hoya株式会社, 謙吾 中村, 義包 新熊 filed Critical Hoya株式会社
Priority to JP2018531910A priority Critical patent/JP6976950B2/ja
Priority to CN201780040003.XA priority patent/CN109415236B/zh
Publication of WO2018025844A1 publication Critical patent/WO2018025844A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses

Definitions

  • the present invention relates to a glass material for press molding and a method for producing an optical element using the same, and more specifically, a glass material for press molding in which at least the surface of a portion that becomes an optical functional surface is a free surface, and the same
  • the present invention relates to a method for manufacturing an optical element using the.
  • Patent Document 1 Conventionally, as a glass material for press molding used when manufacturing an optical element by press molding, for example, there is one described in Patent Document 1.
  • the glass material for press molding described in Patent Document 1 receives a molten glass in a spherical receiving mold, and forms a glass material by holding the molten glass in a state where the molten glass is floated by jetting gas from the receiving surface. It is formed by so-called levitation molding.
  • the glass material for press molding produced by this method has a lower surface formed by a curved surface having a curvature radius substantially the same as the curvature radius of the receiving mold, and the entire surface is formed by a smooth free surface.
  • the field of application of lenses has been expanding, and along with this, diversification of the shape and size of lenses has progressed.
  • a camera with a special projection method in which the center is telephoto and the periphery is wide-angle due to strong distortion.
  • the aspherical lens used is required to have a complicated shape such as a thick wall and a large volume of the entire lens, but a small paraxial radius of curvature.
  • An object of the present invention is to provide a press-molding glass material capable of press-molding an aspheric lens having a large volume and a complicated shape, and an optical element manufacturing method using the same.
  • the glass material for press molding according to the present invention has a rotating body shape centered on the rotation axis, and at least the surface of a portion that becomes a pair of optical functional surfaces after molding is formed as a free surface.
  • the first surface which is the surface of one of the optical functional surfaces in the direction of the rotation axis, is formed in a convex shape outward, and the center of the first surface is glass for press molding.
  • a peripheral portion having a first radius of curvature that is smaller than the radius of a sphere having the same volume as the material and that is disposed adjacent to the central portion around the central portion is a second radius of curvature that is greater than the first radius of curvature. It is characterized by having.
  • a glass material having a smooth surface can be obtained because the surface of the portion that becomes a pair of optical functional surfaces after molding of the glass material for press molding is a free surface.
  • the center portion of the first surface of the press-molding glass material has a first radius of curvature smaller than the radius of a sphere having the same volume, and a second radius of curvature where the peripheral portion is larger than the first radius of curvature. Therefore, even if it is a glass material for press molding having a relatively large volume, the radius of curvature at the center is relatively small and a smoothly continuous overall shape can be obtained.
  • the glass material for press molding is a glass material mainly used for precision press molding and refers to a so-called preform.
  • the free surface refers to a surface when the molten glass is solidified without contacting other members such as a mold, and a surface on which a part of other members is transferred or polished. -Does not include surfaces that have been machined such as grinding.
  • FIG. 1 is a diagram showing a cross-sectional shape including a rotation axis of a press-molding glass material 1 (hereinafter simply referred to as “glass material 1”) according to an embodiment of the present invention.
  • the glass material 1 has at least a surface of an optical function surface formed as a free surface, has a rotating body shape centered on the rotation axis A, and has one surface (lower surface 6) in the direction of the rotation axis A.
  • One surface (lower surface 6) has a first curvature radius R1 smaller than the radius of a sphere having the same volume as that of the glass material 1, and has one surface (lower surface 6).
  • Peripheral portion 10 arranged adjacent to the periphery of has a second radius of curvature R2 that is larger than the first radius of curvature R1. Further, the curvature radius R7 of the other surface (upper surface 4) in the direction of the rotation axis A is larger than the curvature radius R1 of the lower surface 6.
  • the optical functional surface means a region within an effective diameter in an optical element such as an optical lens.
  • an optical element such as an optical lens.
  • part used as the optical function surface in the glass raw material 1 changes variously with the shape and function of an optical element, at least the center of an optical axis (rotation axis A) and its peripheral region can become an optical function surface.
  • the glass material 1 has at least a surface of a portion that becomes a pair of optical functional surfaces after press molding as a free surface, and has a rotating body shape centering on the rotation axis A, and rotates. 1 gradually increases from the bottom of FIG. 1 along the axis A, has a maximum diameter D1 at the maximum diameter position 2, and then gradually decreases again.
  • the upper surface 4 above the maximum diameter position 2 is formed in a convex shape that curves outward, that is, upward.
  • the lower surface 6 below the maximum diameter position 2 is formed in a convex shape that curves outward, that is, downward.
  • S1 is a portion that becomes an optical functional surface on the upper surface 4 side
  • S2 is a portion that becomes an optical functional surface on the lower surface 6 side.
  • 4a and 6a have shown the surface of the site
  • FIG. 2 is a diagram showing the relationship between the volume V of the glass material 1 and the radius of curvature R1 of the central portion 8 according to an embodiment of the present invention.
  • the abscissa represents the curvature radius r
  • the ordinate represents the volume V
  • the curve C represents the relationship between the curvature radius (radius) of the sphere having the volume with respect to the volume.
  • the radius of curvature R1 of the central portion 8 of the glass material 1 of the present embodiment is set so as to be located in a hatched region on the left side of the curve C.
  • the radius of curvature R1 of the central portion 8 of the glass material 1 of the present embodiment is set to be smaller than the radius when a glass material having the same volume V as the glass material 1 is formed in a spherical shape.
  • ⁇ indicates the relationship between the volume of the glass material and the radius of curvature in the example
  • ⁇ indicates the relationship between the volume of the glass material and the radius of curvature in Comparative Example 1.
  • ⁇ show the relationship between the volume of the glass material and the radius of curvature in Comparative Example 2.
  • the glass material 1 is formed by pressing the glass material 1 to form the optical functional surface of the optical element when the optical element is formed (the first surface 6a and the first surface 6a).
  • 2 surfaces 4a) are formed at least as free surfaces.
  • the free surface refers to the surface when the molten glass is solidified without contacting other members such as a mold as described above, and the arithmetic average roughness Ra is 10 ⁇ 3 ⁇ m or less (1 nm or less). This is an extremely smooth surface.
  • the arithmetic average roughness Ra is preferably 0.7 nm or less, and more preferably 0.5 nm or less, from the viewpoint of obtaining surface smoothness after the glass material 1 is press-molded.
  • the glass material 1 has a rotating body shape centered on the rotation axis A, and one surface in the direction of the rotation axis A, that is, the lower surface 6 is formed in a convex shape outward, and the lower surface 6 has a center
  • the portion 8 has a first radius of curvature R1 that is smaller than the radius of the sphere of the same volume, and the peripheral portion 10 disposed around the central portion 8 and adjacent to the central portion 8 is more than the first radius of curvature R1.
  • the first radius of curvature R1 is, for example, 2 to 10 mm, preferably 3 to 8 mm, and more preferably 4 to 7 mm.
  • the second radius of curvature R2 is, for example, 5 to 30 mm, but is not limited to this range.
  • the ratio (L2 / L1) of the distance L2 to the point where the rotation axis A intersects is preferably set to 1.2 to 1.7. If the ratio of the distance L2 to the distance L1 is out of the above range, the stability of the glass material 1 when the glass material 1 is placed on a press molding die is deteriorated, and the rotation axis A of the glass material 1 is formed. It becomes difficult to align with the central axis of the mold.
  • the thickness T of the rotation direction A direction of the glass raw material 1 shown in FIG. 1 is the sum total of the distance L1 and the distance L2.
  • the lower limit of the ratio (L2 / L1) is preferably 1.2 or more from the viewpoint of suppressing the occurrence of gas traps during press molding.
  • the glass material 1 is formed by so-called flotation molding, in which molten glass is received by a mold, gas is ejected from the receiving surface of the mold, and the molten glass is held in a floated state to mold the glass material. Accordingly, the entire surface of the glass material 1 is a free surface.
  • the mold is made of, for example, a porous material.
  • the shape of the mold is such that when the molten glass supplied to the mold is lifted and supported by the floating gas from the surface of the mold, the distance between the mold and the molten glass is the smallest at the periphery, and the center portion In this case, the distance between the mold and the molten glass is maximized.
  • the shape of the mold is formed such that the pressure of the floating gas received on the surface of the molten glass in the mold is the highest in the peripheral portion and the lowest pressure distribution in the central portion.
  • a plurality of molds are arranged at equal intervals on the circumference of the turntable, and the turntable is configured to be rotatable by a predetermined angle.
  • a floating gas supply source is connected below the mold.
  • the mold is heated with a heater so that the shape of the glass material 1 is distorted or cracked, and the glass material 1 does not stick when the glass material 1 comes into contact with the mold surface. The temperature is adjusted.
  • the floating gas When the floating gas is supplied from below the mold configured as described above, the floating gas is ejected from the mold. When a predetermined amount of molten glass is supplied into the mold, the molten glass floats up from the mold due to the pressure of the floating gas. Oppositely, the lower surface 6 of the glass material 1 is formed, and is formed into a predetermined shape as shown in FIG. 1 as a whole.
  • the material of the glass to be used is not particularly limited. For example, lanthanum borate glass mainly containing boric acid and rare earth oxide, phosphate glass mainly containing phosphate, fluorine and phosphorus. A fluorophosphate glass mainly composed of an acid salt, a borosilicate glass mainly composed of a borosilicate, and the like can be used.
  • the molten glass moves on the turntable while being molded in the mold, and is cooled to a temperature range that does not deform even when an external force is applied to form the glass material 1. Thereafter, the glass material 1 is taken out of the mold and gradually cooled.
  • the molded glass material 1 may be washed as necessary, and a carbon film may be formed on the entire surface as necessary. Such a carbon film improves the slip of the glass and improves the mold releasability of the molded optical element when the glass material 1 is press-molded into the optical element.
  • the glass material 1 molded into the shape as shown in FIG. 1 is accommodated in a press molding mold, the mold is heated, the glass material 1 is softened and pressed to obtain an optical element having a predetermined shape.
  • the radius of curvature R1 of the central portion 8 of the glass material 1 is formed to be smaller than the radius of curvature of the press-molding die at a position facing the central portion 8. Therefore, the softened glass material 1 comes into contact with the press-molding die from the central portion 8 on the lower surface 6, and the shape of the die is gradually transferred toward the outside and molded into a desired shape.
  • FIG. 3 is a diagram illustrating an example of a cross-sectional shape of an optical element obtained by press molding a glass material for press molding according to an embodiment of the present invention.
  • the outer peripheral portion of the molded body obtained by press-molding the glass material 1 has a surplus portion 26 as shown by a broken line.
  • the portion where the surplus portion 26 is removed by centering is the optical element 16.
  • the optical element 16 shown in FIG. 3 has a paraxial radius of curvature R3 that becomes the central portion 18 is relatively small (for example, a radius of curvature of 10 mm or less), and inward along the shaft 20 around the central portion 18 (FIG. 3).
  • a curved portion 22 that is recessed upward is formed. Further, the surface opposite to the center portion 18 (the upper surface in FIG.
  • the optical element 16 has a complicated shape as a whole, and is relatively thicker than the conventional one.
  • part and range which perform a cold work differ according to the range of the optical function surface of an optical element. Therefore, the range and shape of the surplus portion 26 shown in FIG.
  • the following effects can be obtained. Since the entire surface of the glass material 1 is formed with a free surface, a glass material 1 having a smooth surface is obtained. When an optical element is obtained by press-molding the glass material 1, an optical element having a good appearance and shape quality Can be obtained.
  • the conventional glass material has a spherical shape or an elliptical shape with a radius of curvature larger than the radius of the sphere.
  • the radius of curvature naturally increases accordingly. For this reason, for example, when trying to press-mold an aspheric lens with a complicated shape with a conventional glass material with a large volume, if the paraxial radius of curvature of the aspheric lens is small, the curvature radius of the glass material will be press-molded. It becomes larger than the radius of curvature of the metal mold for use, and gas accumulates between the glass material and the metal mold, so that an optical element having a good shape cannot be obtained.
  • the curvature radius R1 of the center part 8 of the lower surface 6 of the glass material 1 is set smaller than the radius of the sphere having the same volume as the volume V of the glass material 1, comparison is made. Even in the case of the glass material 1 having a large target volume, the radius of curvature R1 of the central portion 8 can be formed small. Therefore, even in the case of molding a thick and complex optical element with a small paraxial radius of curvature, a molded product having a good shape can be obtained without causing a gas trap.
  • the radius of curvature R2 of the peripheral portion 10 of the glass material 1 is formed larger than the radius of curvature R1 of the central portion 8, from the central portion 8 having a small radius of curvature R1 to the peripheral portion 10 having a larger radius of curvature R2.
  • the transition region becomes smooth, and a continuous and smooth shape is obtained as a whole.
  • the ratio of the distance L2 to the lower surface 6 with respect to the distance L1 from the maximum diameter position 2 to the upper surface 4 of the glass material 1 is appropriately set, so that the first curvature of the central portion is ensured while ensuring a relatively large volume.
  • the radius R1 can be made relatively small, and even when the glass material 1 is press-molded into an aspheric lens having a complicated shape, an optical element with good quality can be obtained without causing a shape defect. be able to.
  • the ratio of the distance L2 to the distance L1 is appropriately set, when the glass material 1 is placed on a press molding die, the glass material 1 can be stably placed in the die. it can. Therefore, the rotation axis A of the glass material 1 can be easily and surely aligned with the central axis of the mold, and an optical element having a good quality free from defects such as uneven thickness can be formed.
  • a glass material 1 having a volume V of 547 mm 3 was produced using the above-described float forming.
  • the radius of curvature R1 of the central portion 8 of the glass material 1 was 4.2 mm.
  • This glass material 1 has the relationship between the volume and the radius of curvature shown by (2) in FIG. 2, which is in the hatched region on the left side of the curve C in FIG. Further, the entire surface of the glass material 1 is a free surface.
  • Known methods were used for the method of supplying and cutting the molten glass, the floating conditions on the mold surface of the molten glass, and the like.
  • the obtained glass material 1 was heated and softened, precision press-molded, and press-molded into an optical element 16 having a cross-sectional shape as shown in FIG.
  • the curvature radius R3 of the central portion 18 of the convex surface of the obtained optical element 16 was 4.7 mm
  • the curvature radius R4 of the concave surface 23 was 2.2 mm.
  • the press-molding die was formed in a shape corresponding to the shape of the optical element 16.
  • FIG. 4 is a view showing a cross-sectional shape of the glass material 24 of Comparative Example 1 of the present invention.
  • a glass material 24 having a volume V of 250 mm 3 was produced using flotation molding.
  • the radius of curvature R5 at the center of the glass material 24 was 4.5 mm.
  • the glass material 24 has a relationship between the volume indicated by ⁇ in FIG. 2 and the radius of curvature, which is outside the hatched region on the right side of the curve C in FIG.
  • the desired thickness and diameter were not particularly obtained, and the shape accuracy of the optical element was significantly deteriorated as compared with the Examples.
  • Comparative Example 2 of the present invention will be described.
  • a spherical glass material 24 having a volume of 550 mm 3 was produced by cold working.
  • the radius of the obtained spherical glass material was 5.1 mm.
  • This glass material has a relationship between the volume and the radius of curvature indicated by ⁇ in FIG. 2, which is on the curve C in FIG.
  • a gas trap was generated in the central portion 18 of the optical element 16.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
  • Surface Treatment Of Glass (AREA)

Abstract

La présente invention concerne un matériau de verre (1) possédant une forme de corps rotatif qui est centrée sur un axe de rotation (A) et est telle qu'au moins les surfaces des zones qui doivent être réalisées en une paire de surfaces fonctionnelles optiques après le formage sont formées en tant que surfaces libres. Une surface inférieure (6) dans la direction de rotation de l'axe (A) est formée selon une forme saillant vers l'extérieur. La surface inférieure (6) comprend une partie centrale (8) possédant un premier rayon de courbure (R1) qui est plus court que le rayon d'une sphère possédant le même volume que le matériau de verre (1). Une partie périphérique (10), disposée adjacente à la partie centrale (8) à la périphérie de la partie centrale (8), possède un second rayon de courbure (R2) qui est plus long que le premier rayon de courbure (R1).
PCT/JP2017/027844 2016-08-01 2017-08-01 Matériau de verre formant une presse et procédé de production d'un élément optique utilisant ledit matériau de verre formant une presse WO2018025844A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2018531910A JP6976950B2 (ja) 2016-08-01 2017-08-01 プレス成形用ガラス素材及びこれを用いた光学素子の製造方法
CN201780040003.XA CN109415236B (zh) 2016-08-01 2017-08-01 模压成型用玻璃坯料和使用该玻璃坯料的光学元件的制造方法

Applications Claiming Priority (2)

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JP2016151541 2016-08-01
JP2016-151541 2016-08-01

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007099529A (ja) * 2005-09-30 2007-04-19 Hoya Corp 精密プレス成形用プリフォームおよびその製造方法ならびに光学素子の製造方法
JP2011068506A (ja) * 2009-09-24 2011-04-07 Ohara Inc ガラス成形体の製造方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4460339B2 (ja) * 2004-03-30 2010-05-12 Ｈｏｙａ株式会社 モールドプレス成形装置及び光学素子の製造方法
CN101076501A (zh) * 2004-12-13 2007-11-21 株式会社小原 光学元件预型体和光学元件
JP2007197241A (ja) * 2006-01-25 2007-08-09 Konica Minolta Opto Inc 光学ガラス素子の成形方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007099529A (ja) * 2005-09-30 2007-04-19 Hoya Corp 精密プレス成形用プリフォームおよびその製造方法ならびに光学素子の製造方法
JP2011068506A (ja) * 2009-09-24 2011-04-07 Ohara Inc ガラス成形体の製造方法

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CN109415236B (zh) 2022-08-09
JPWO2018025844A1 (ja) 2019-07-18
JP6976950B2 (ja) 2021-12-08
CN109415236A (zh) 2019-03-01

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