JP2008110476A - Lens holding method and manufacturing method for glasses lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve precision and stability of strength of lens by preventing deformation of the lens due to thermal compression of alloy as much as possible even if the lens has a high refractive index and to manufacture such lens that causes no distortion over the whole surface of the lens. <P>SOLUTION: This lens manufacturing method comprises processes for deciding a combination of a blocking ring 14 with an auxiliary appliance 13 in such a way that thickness of the center of the alloy 16 is within a predetermined scope per lens specified by diameter and a base curve of convex in advance and selecting the blocking ring 14 and the auxiliary appliance 13 to be used in accordance with the lens 5 to be held based on the combination decided in advance. The combination of the blocking ring 14 and the auxiliary appliance 13 for the lenses 5 having the same diameter and different base curves of the convexes is selected from among one kind of blocking ring or a plurality of kinds of blocking rings having different heights and a plurality of kinds of auxiliary appliances having different heights. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens holding method for holding an optical lens such as a spectacle lens and a method for manufacturing a spectacle lens using the holding method.

  Conventionally, as a method for manufacturing optical lenses, particularly plastic lenses for spectacles, from a lens material (for example, semi-finished lens) that is thicker than the finished dimensions, an NC (numerical value) controlled grinding machine (hereinafter referred to as a curve generator) is used. By cutting the lens material into a predetermined surface shape with the above, a lens that is slightly thicker than the finish dimensions that allow for sand allowance and polishing allowance is manufactured, and this lens is manufactured by polishing with a polishing device. ing.

  As a polishing apparatus, for example, a commercially available general-purpose polishing apparatus (TORO-X2SL) manufactured by LOH is used for polishing the lens. This polishing apparatus includes an arm that can move in the left-right direction and reciprocally rotate in the front-rear direction, and a swinging device that swings and swings around a vertical axis. When polishing the concave surface of the lens, a lens is attached to the arm via a lens holder, a polishing jig is attached to the swinging device, and a polishing pad is disposed on the upper surface of the polishing jig to provide a concave surface of the lens. In this state, the arm is reciprocated back and forth in the left and right directions, and the swinging movement of the rocking device is swung so that the locus of polishing slightly shifts every round. Is polished with the polishing pad and an abrasive.

  In the cutting process and polishing process, the lens holder that holds the lens is made of Yatoi and a low melting point alloy (hereinafter also referred to as an alloy). For example, the lens is attached to the lens holder by a device called a layout blocker manufactured by LOH. ing. In order to attach the lens to the lens holder, a scratch-preventing protective film is brought into close contact with the convex surface (processed surface) of the lens in advance. Next, a yatoy is fitted on the mounting block of the layout blocker, the periphery thereof is surrounded by a blocking ring, and a lens having the protective film adhered thereto is placed on this ring with its convex surface down. Thus, the blocking ring supports the convex surface of the lens by the inner peripheral edge on the upper surface side. Then, the molten alloy is poured into a space surrounded by the lens, the yatoy, the blocking ring, and the mounting base to solidify the lens, thereby fixing the lens to the yatoy.

  There are four types of semi-finished lenses (lenses that optically finish only the first refracting surface) when classified according to size, for example, 80, 75, 70, and 65 mm in diameter. However, there are several types depending on the refractive power (frequency) of the first refractive surface of the lens.

The refractive power (frequency D: diopter) of the spectacle lens is approximately represented by the sum (D = D1 + D2) of the refractive power D1 of the first refractive surface (convex surface) and the refractive power D2 of the second refractive surface (concave surface). Is done. The refractive power (surface refractive power) of the first refracting surface and the second refracting surface is determined by the curvature ρ (unit: 1 / m, curvature radius R = 1 / ρ) of the surface and the refractive index n of the lens material. It is defined as:
Surface power = (n−1) × ρ = (n−1) / R
The refractive power D1 of the first refracting surface is particularly called a base curve (hereinafter abbreviated as BC).

  As a conventional lens holder, for example, one described in Patent Document 1 is known. This lens holding part is shown in FIG. In the figure, A is Yatoi, B is a lens, and C is an alloy. This yatoy A has a concave portion D on a surface a facing the lens B, and a stepped portion E is formed on the outer periphery of the concave portion D at an acute angle. Further, the recess D is provided with a plurality of indentations F dug in the vertical direction. The step E functions to prevent the alloy C from coming off, and the dent F serves to prevent the rotation of the yatoy A relative to the alloy C, so that the yatoy A and the alloy C are firmly coupled.

  In the case where the lens B is held using such a Yatoi A and an alloy C, it is known that the lens B is deformed by the influence of the heat of the alloy C or the contraction when the alloy C is solidified (for example, Patent Document 2). reference).

  However, conventionally, as the material of the plastic spectacle lens, diethylene glycol bisallyl carbonate resin (n = 1.50), which is the most general plastic lens material, is used, and the thickness of the semi-finished lens is designed to be thick. Therefore, the influence of the heat and shrinkage of the alloy was small when the lens was fixed to the Yatoi through the low melting point alloy solidified with the alloy.

US Pat. No. 5,421,770 JP-A-7-116950

  However, recently, as the refractive index of the lens material has been increased and the semi-finished lens has been made thinner, the influence of the heat and shrinkage of the alloy has increased, and improvement of the lens holder has been urgently required. That is, as a lens material, a urethane resin or an epithio resin having a refractive index of 1.55 to 1.75 is used instead of a diethylene glycol bisallyl carbonate resin having a refractive index of 1.5, and the material cost is reduced. If the semifinished lens is made thinner and the amount of shaving on the concave surface is reduced due to demands for resource saving, the influence of heat and shrinkage of the alloy will increase, especially in the case of semifinished lenses for negative lenses, the center thickness of the lens Because it is thin, it is greatly affected by the heat and shrinkage of the alloy. In addition, the conventional lens holder has a large influence on the heat and shrinkage of the alloy because the amount of the alloy near the center is large due to the structure as described above for strengthening the connection strength between the alloy and the Yatoi. .

  For this reason, in Japanese Patent Laid-Open No. 7-116950 described above, a bottom plate is provided in the space between the yatoi and the lens to reduce the amount of alloy and prevent deformation due to shrinkage during solidification. However, even if the amount of the alloy used is reduced, the thickness of the central portion of the alloy differs depending on the type of lens, so that the influence of heat and shrinkage still cannot be eliminated.

  In addition, since only the central part of the lens is conventionally held by the alloy, there is a difference in the strength of the lens between the central part where the alloy is present and the outer part where the alloy is not present. When polished, there is also a problem that a polishing mark is generated at a portion corresponding to a boundary portion between the concave portion and the convex portion side where the alloy exists.

Therefore, the present inventors conducted various experiments by changing the height of the yatoi and the blocking ring, so that the center thickness of the alloy is substantially constant regardless of the size and shape (particularly BC) of the lens. It was found that setting the height of the yatoi and blocking ring can reduce the effects of heat and shrinkage of the alloy, and improve the accuracy and stability of the lens power.
In addition, when the inner diameter of the blocking ring is made substantially equal to the diameter of the lens and the alloy is fixed to substantially the entire surface of the convex surface of the lens, no polishing mark is generated at the boundary between the portion where the alloy is present and the portion where the alloy is not present, It was found that a lens without distortion can be produced.
Furthermore, if the hole formed on the surface facing the Yatoi lens is tilted so that the opening is on the outside of the inner end, the thickness of the center of the alloy will not increase, and the effects of heat and shrinkage can be reduced. I found.

The present invention has been made on the basis of the above-described conventional problems and experimental results, and the object of the present invention is to make the center thickness of the alloy substantially constant regardless of the difference in the size and shape of the lens. To provide a lens holding method capable of reducing the deformation of a lens due to heat shrinkage of an alloy as much as possible even with a shaped semi-finished lens and improving the accuracy and stability of the lens power. is there.
Another object of the present invention is to provide a lens holding method capable of producing a lens having no distortion over the entire surface of the lens.
It is another object of the present invention to provide a method for manufacturing a spectacle lens in which the bond strength between an alloy and a yatoi is high, the thickness of the central portion of the alloy is not increased, and the influence of heat and shrinkage can be reduced.

  In order to achieve the above object, the first aspect of the present invention is to inject the molten low melting point alloy into a space between the convex surface of the lens and the space between the yatoy and the blocking ring to solidify the lens through the low melting point alloy. In the lens holding method for fixing to the Yatoi, for each lens specified by the diameter and the convex base curve, a combination of a blocking ring and Yatoi in which the center thickness of the low melting point alloy is within a predetermined range is determined in advance. And having the step of selecting a blocking ring and a yatoy to be used according to the lens to be held based on the predetermined combination, and the predetermined blocking for lenses having the same diameter and different convex base curves. The combination of ring and Yatoi is a type of blocking ring or multiple types of blocking blocks with different heights. A plurality of types of blocking rings having different heights at intervals wider than a predetermined range width of the center thickness of the low-melting-point alloy. A ring is included, and the plurality of types of yatoys include a plurality of types of yatoys having different heights at intervals equal to or less than a predetermined range width of the center thickness of the low melting point alloy. .

  According to a second aspect of the present invention, in the first aspect of the present invention, the types of Yatoi having different heights used in the combination of the predetermined blocking ring and the Yatoi for lenses having the same diameter and different convex base curves are as follows: The height is higher than that of different types of blocking rings.

  According to a third invention, in the first or second invention, the blocking ring used in the predetermined combination of the blocking ring and the yatoy for lenses having the same diameter and different convex base curves is one kind. The blocking ring or two types of blocking rings having different heights are used.

  According to a fourth invention, in any one of the first, second, and third inventions, the predetermined combination of the blocking ring and the yatoy for lenses having the same diameter and different convex base curves The plurality of types of yatoi having different heights used in the above-mentioned method include a plurality of types of yatoi having different heights at a constant interval equal to or less than a predetermined range width of the center thickness of the low melting point alloy. It is.

  5th invention cuts the surface on the opposite side to the side by which this spectacle lens was hold | maintained in the state which hold | maintained the spectacle lens by the lens holding method in any one of the said 1st-4th invention. A polishing step is included.

  In the first invention, the center thickness of the alloy can be set within a set range for any diameter and BC lens (paragraph “0045”).

  In the second invention, the center thickness can be set within the setting range with a small number of blocking rings, which is preferable.

  In the third invention, storage management of the blocking ring is easy.

  In the fourth aspect of the invention, it is easy to manage yatoys.

  In the fifth invention, the influence of heat and shrinkage of the alloy can be reduced, and the accuracy of the lens power can be stably maintained (paragraph “0064”).

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 is a schematic configuration diagram of a polishing apparatus using a lens holding method according to the present invention, FIG. 2 is a sectional view showing a state in which a lens holder is attached to a lens, and FIG. 3 is a layout blocker for attaching the lens holder to the lens. 4 (a), 4 (b), and 4 (c) are plan views, a cross-sectional view and a bottom view, and FIGS. 5 (a) and 5 (b) are a plan view and A of a blocking ring. FIG. 6 (a) to 6 (d) are diagrams showing the relationship between the types of lenses, blocking rings and Yatoi, and the gap between the center of the lens and Yatoi, FIG. 7 is a plan view of the polishing jig, and FIG. 8 is VIII in FIG. -VIII sectional view, FIG. 9 is a sectional view of the valve, FIG. 10 is a plan view of the polishing pad, FIG. 11 is a perspective view of the fastening member of the polishing pad, and FIGS. It is a conceptual diagram which shows a trackless grinding | polishing locus | trajectory.

  In this embodiment, an example is shown in which the present invention is applied to cutting and polishing a concave surface made of a toric surface of a plastic spectacle lens for correcting astigmatism. As the lens 5 to be cut and polished, a semi-finished lens in which only a convex surface made of a urethane or epithio resin having a high refractive index (n = 1.55 to 1.75) was finished was used.

  In manufacturing the lens, first, the lens holder 7 is attached to the convex surface 5a of the lens 5, the lens 5 is attached to the curve generator via the lens holder 7, and the concave surface 5b of the lens 5 is cut into a predetermined shape. Similarly, the lens 5 is attached to the polishing apparatus via the lens holder 7 and the cut surface is polished.

  In order to attach the lens 5 to the lens holder 7, as shown in FIG. 2, a scratch-preventing protective film 12 is brought into close contact with the convex surface 5a of the lens 5 in advance, and is called a layout blocker made by LOH, for example. The lens holder 7 is attached by an apparatus. As the type of the lens 5, four types having a diameter (φ) of 80, 75, 70, and 65 mm are used.

  2 to 5, the lens holder 7 is composed of a yatoe 13 and a low melting point alloy (hereinafter also referred to as alloy) 16, and the yatoe 13 and the outer periphery of the yatoe 13 are mounted on a mounting block 15 of the layout blocker. An enclosing blocking ring 14 is fitted, and the lens 5 with the protective film 12 adhered thereto is placed on the blocking ring 14 with the convex surface 5a facing downward, and the lens 5, the yatoe 13, the blocking ring 14 and the mounting base 15 are placed. The molten alloy 16 is filled in the space surrounded by the solidified material and solidified. Next, the integrated body consisting of the lens 5, the yatoe 13, the blocking ring 14 and the alloy 16 is removed from the mounting base 15, and the blocking ring 14 is further removed. As a result, the lens 5 is held by the lens holder 7 composed of the yatoe 13 and the alloy 16. In addition, in order to make the alloy 16 flow easily, the mounting base 15 to which the Yatoy 13 is fitted is inclined forward and downward at an angle of 40 to 45 °.

The structures of the yatoy 13 and the blocking ring 14 will be described in more detail with reference to FIGS.
In FIG. 4, the yatoy 13 is formed in a cup shape by SUS303 or the like, so that a disc portion 13A and an annular projection 13B having a trapezoidal cross section formed integrally on the outer peripheral portion of the lower surface of the disc portion 13A It consists of The upper surface of the disc portion 13A forms a flat surface. The annular protrusion 13B has a recessed portion 18 on the inner side, and two positioning recesses 19 are formed in the circumferential wall of the annular protrusion 13 so as to be separated from each other by 180 ° in the circumferential direction. It fits into the formed annular recess 20 (FIG. 3). A frustoconical protrusion 21 that fits into the recess 18 is integrally provided at the center of the annular recess 20, and further, the groove bottom of the annular recess 20 is fitted into the positioning recess 19 2. Two positioning portions (not shown) are integrally projected.

  Such yatoe 13 has a plurality of types having different heights H so that the center thickness M (FIG. 2) of the alloy 16 falls within a predetermined range. In the present embodiment, as shown in FIG. 6 to be described later, seven types of yatoe 13 having different heights H are used.

  The diameter D1 of the yatoy 13 is constant regardless of the difference in the diameter and BC of the lens 5 and is set to 43 mm, for example. The recessed portion 18 provided at the center of the bottom surface of the yatoy 13 is formed so as to have the same size and depth for all the yatoies so as to fit the protruding portion 21 of the mounting base 15 (for example, the depth d). = 15 mm). Further, four holes 22 having a diameter of about 4 mm and a depth of about 7 mm are formed at equal intervals in the circumferential direction near the outer periphery of the upper surface of the yatoy 13. These four holes 22 are non-through holes inclined at about 60 ° in the radial direction of the yatoy 13 so that the opening 22a is located near the outer periphery of the yatoy 13 and the inner end 22b is located on the center side of the yatoy 13. The holes 22 formed in this way are all different in the direction of the holes, and the fitting of the alloy 16 and the yatoe 13 that has entered and solidified into the holes 22 has a strong binding force in all directions. It is possible to prevent the alloy 16 from being peeled off, dropped off, or rotated. Further, since the opening 22a is closer to the outer periphery of the yatoy 13, since the amount of the alloy 16 at the center of the yatoi is small, the deformation of the lens 5 due to the contraction of the alloy 16 can be reduced.

  In FIG. 5, the blocking ring 14 is formed of SUS303 or the like in the same manner as the yatoy 13 and has a predetermined inner diameter and height corresponding to the diameter of the lens 5 and BC. The outer diameter Da of the blocking ring 14 is larger than the diameter of each lens 5 having a different diameter, the inner diameter Db is set substantially equal to the diameter of the lens 5 (strictly, about 2 mm smaller than the lens diameter), and the height H0 is the lens. 5 corresponding to 5 BC. For this reason, in the present embodiment, six types of blocking rings 14 having different inner diameters Db (four types) and heights H0 (two types) (one type for 80φ and 75φ lenses each) are used. It is done.

  The blocking ring 14 is formed with two positioning holes 23, an alloy flow passage 24 and an alloy inlet 25. The two positioning holes 23 are through-holes opened on the upper and lower surfaces of the blocking ring 14, and are provided at equal intervals in the circumferential direction of the blocking ring 14. The alloy flow passage 24 is formed of a radial groove formed at an equal distance from the two positioning holes 23 on the upper surface of the blocking ring 14, and an outer end communicates with the alloy inlet 25. The inner end communicates with the central hole 26 of the blocking ring 14. The alloy inflow port 25 is configured by a recess formed on the outer periphery of the blocking ring 14.

  Such a blocking ring 14 is formed by fitting the positioning hole 23 and a position pin 27 (FIG. 3) protruding from the upper surface of the mounting base 15 when the yatoy 13 is installed on the mounting base 15. When positioned and installed on the mounting base 15 and fixed by a fixture 28 such as a bolt, the alloy inlet 25 is connected to the alloy supply port of the layout blocker and surrounds the periphery of the yatoy 13. Then, the lens 5 is placed on the blocking ring 14 with the convex surface 5a facing down, and the lens 5 is pressed against the blocking ring 14 by an appropriate pressing member. Then, when the alloy 16 melted in this state is supplied to the alloy inlet 25, the alloy 16 passes through the alloy flow passage 24 and the center of the blocking ring 14 because the mounting base 15 is inclined downward. The lens 5 flows into the hole 26 and is supplied to the upper surface and the outer periphery of the yatoy 13 and is cooled and solidified to fix the lens 5 to the yatoy 13. The yatoy 13 and the blocking ring 14 to be used are appropriately selected according to the diameter and BC of the lens 5. In this embodiment, the selection is made according to FIG. For example, when the lens 5 having a diameter of 70 mm and a BC of 3.0 is polished, a Yatoi 13 having a height of 18.5 mm and a blocking ring 14 having an inner diameter of 68 mm and a height of 7 mm are shown in FIG. Select.

FIGS. 6A to 6D show the dimensional relationship between the types of lenses, blocking rings and Yatoi, and the gap between the lens center and Yatoi (= the center thickness of the alloy).
The figure (a) is an inner diameter of a blocking ring used for six types of lenses having a diameter of 80 mm and BCs of 1.5, 1.0, 0.9, 0.8, 0.7, and 0.6, respectively. And the height, the height of the yatoy, and the gap between the center of the lens and the upper surface of the yatoy (= the center thickness of the alloy).

  The blocking ring 14 has an inner diameter of 78 mm and a height of 10 mm regardless of the lens BC. Therefore, the blocking ring 14 is one type for a lens having a diameter of 80 mm. On the other hand, Yaito 13 has a height of 225. Two types of mm and 23.5 mm are used. The gap at the center of the lens 5 and the yatoy 13 is 2.88 mm at the maximum and 2.34 mm at the minimum.

  FIG. 5B shows the inner diameter and height of a blocking ring used in five types of lenses having a diameter of 75 mm and BCs of 2.0, 1.75, 0.5, 0.4, and 0.3, respectively. Shows the height of Yatoi and the gap between the center of the lens and Yatoi. The blocking ring 14 has an inner diameter of 73 mm and a height of 7 mm regardless of the lens BC. Therefore, the blocking ring 14 is one type for a lens having a diameter of 75 mm. On the other hand, two types of Yaito 13 having a height of 19.5 mm and 20.5 mm are used. The gap at the center of the lens 5 and the yatoy 13 is 2.80 mm at the maximum and 1.90 mm at the minimum.

The figure (c) is an inner diameter of a blocking ring used for six kinds of lenses having a diameter of 70 mm and BCs of 4.5, 3.75, 3.0, 2.5, 0.2, and 0.1, respectively. And the height, the height of the yatoi, and the gap between the center of the lens and the yatoy.
The blocking ring 14 has two inner diameters of 68 mm and a height of 10 mm and 7 mm regardless of the lens BC. Three types of yatoe 13 having a height of 18.5 mm, 19.5 mm, and 20.5 mm are used. The gap at the center of the lens 5 and the yatoy 13 is 2.89 mm at the maximum and 2.01 mm at the minimum.

The figure (d) shows the inner diameter and height of the blocking ring used for five types of lenses having a diameter of 65 mm and BC of 7.5, 6.75, 6.0, 5.25, and 0, respectively. Shows the height and the gap between the center of the lens and Yatoi.
For the blocking ring 14, two types having an inner diameter of 63 mm and a height of 10 mm and 7 mm are used regardless of the BC of the lens. Four types of yatoe 13 having a height of 17.5 mm, 18.5 mm, 19.5 mm, and 21.5 mm are used. The gap at the center of the lens 5 and the yatoy 13 is 2.66 mm at the maximum and 1.95 mm at the minimum.

  In the present embodiment, seven types of yatoys 13 and six types of blocking rings 14 (two types of heights) are used.

  Moreover, as a kind of the blocking ring 14 used for every lens kind from which a diameter differs, about 1-2 kinds are desirable, and since storage management becomes complicated if it is more than it, it is not preferable.

  In addition, it is more preferable to set the center thickness of the low melting point metal within a predetermined range so that the type of height of the yatoe 13 is larger than the type of height of the blocking ring 14. Since the blocking ring 14 is troublesome to attach and remove, and its manufacturing cost is high, it is better in terms of workability and manufacturing cost by increasing the number of types of Yatoi that are easy to remove and inexpensive to manufacture.

  It is more preferable that the heights of the plurality of types of yatoe 13 are set as follows. The center thickness of the alloy to be set first is set within a range of 1.90 to 3.00 mm. Then, the height of the yatoi is set at an interval equal to or less than the difference between the upper limit value and the lower limit value of the set range (hereinafter referred to as range width). It is more preferable to keep this interval constant because management is easy. For example, when the center thickness of the alloy is set in the range of 1.90 to 3.00 mm as in the present embodiment, the range width of the set range is 1.10 mm, so the height is less than this. A different Yatoi is provided. In this embodiment, seven types of Yatoi were produced at a constant interval of 1.00 mm, and used for blocking rings having different heights at intervals (3 mm) wider than the range width. Similarly, when the center thickness of the alloy is set in the range of 1.90 to 2.50 mm, the range width is 0.6 mm, so it is preferable to set yatoys having different heights at intervals smaller than that.

  The center thickness of the alloy for any diameter and BC lens can be obtained by combining a plurality of Yatoi heights set at intervals below the range width as described above with a blocking ring having an appropriate height and diameter. Can be set within the setting range, which is preferable. And it is more preferable that the center thickness can be set within the setting range with a small number of blocking rings by increasing the type of yatoy having the height set as described above to the type of the height of the blocking ring. Note that it is only necessary to prepare the necessary types according to the diameter of the lens to which the lens holder is to be attached and the type of BC. Therefore, the height intervals of all the yatoi are not necessarily less than the set range width. There is no need.

  As described above, in the present invention, seven types of yatoe 13 and six types (two types of height) blocking ring 14 are prepared for cutting and polishing the concave surfaces of four types of lenses 5 having different diameters. By selecting and using them corresponding to the diameter of 5 and BC, the distance between the center of the convex surface 5a of the lens 5 and the upper surface of the yatoy 13, in other words, the center thickness M of the alloy 16 is set to a substantially constant value, specifically Was set in the range of 1.90 to 3.00 mm as described above. If the gap is 1.9 or less, the melted alloy 16 may not flow into the gap between the lens 5 and the yatoe 13, and the alloy 16 may adhere to the lens surface non-uniformly and cause a power failure. Absent. If the gap is 3.00 or more, the amount of alloy 16 used is increased, the influence of heat and shrinkage of the alloy 16 increases, the lens 5 becomes unstable, and the shape error of the concave surface 5b also increases. In addition, it is more preferable when it is set to 1.9-2.5 mm.

  The lens 5 to which the lens holder 7 is attached as described above is attached to a curve generator that performs three-dimensional NC control via the lens holder 7, and the concave surface 5b is cut into a predetermined surface shape ( Processing accuracy within 3 μm: 50φ, surface roughness Ry 0.3-0.5 μm).

The lens 5 that has been cut is polished by a polishing device. Hereinafter, a schematic configuration of a polishing apparatus using the lens holder according to the present invention will be described.
In FIG. 1, a spectacle lens polishing apparatus generally indicated by reference numeral 1 includes an apparatus main body 2 installed on a floor surface, and the apparatus main body 2 is movable in the left-right direction on the paper surface and has a horizontal axis 3 as a center. Provided on the arm 4, an arm 4 that is rotatably arranged in a direction orthogonal to the axis, a drive device (not shown) that reciprocates the arm 4 in the left-right direction and that rotates in a direction orthogonal to the paper surface. The lens mounting portion 6 is disposed in the apparatus main body 2 so as to be positioned below the lens mounting portion 6, and swings and swings around the vertical axis K (does not rotate) by a driving device (not shown). A rocking device 8 and the like are provided. Further, a polishing jig 9 detachably provided on the rocking device 8, a polishing pad 10 detachably attached to the polishing jig 9, a lifting device 11 for raising and lowering the lens mounting portion 6, and the like are provided. ing. The cut lens 5 is attached to the lens mounting portion 6 via the lens holder 7 (FIG. 2).

  Such a polishing apparatus 1 is widely used from the past except for the new structure of the lens holder 7 and the polishing jig 9. For example, a general-purpose spherical polishing apparatus manufactured by LOH which is generally available on the market. (TORO-X2SL) is used to polish the lens 5.

  The oscillating device 8 is attached to the vertical rotating shaft 31 so as to swing and swing at an oscillating angle α (for example, 5 °), and the polishing jig 9 is attached to the upper surface.

  7 to 11, the polishing jig 9 includes a balloon member 31 formed in a cup shape by natural rubber, synthetic rubber or rubber-like resin, which is an elastic material, and a back side of the balloon member 31. It comprises a fixture 32 that closes the opening and keeps the inside airtight, and a valve 33 that supplies compressed air to the inside of the balloon member 31.

  The balloon member 31 includes a dome part 31A having a substantially elliptical shape with a flat or gentle convex curved surface, a substantially elliptical cylindrical part 31B integrally extending on the outer periphery of the lower surface of the dome part 31A, and a cylindrical part. It is comprised with the cyclic | annular inner flange 31C integrally extended by the rear end of 31B. As the material of the balloon member 31, for example, synthetic rubber (for example, IIR) or natural rubber close to natural rubber having a hardness of 20 to 50 degrees (JIS) is used. The thickness T of the balloon member 31 is substantially uniform throughout, and is about 0.5 to 2 mm (usually equal to about 1 mm). It is preferable to prepare a plurality of types of balloon members 31 according to the size of the lens 5 to be polished and the shape of the surface to be polished.

  The fixing tool 32 is composed of two members, an inner fixing tool 34 and an outer fixing tool 35, and the balloon member 31 is clamped from the inner side and the outer side by sandwiching the lower end portion of the cylindrical portion 31B of the balloon member 31 and the inner flange 31C. The rear side opening 31 is hermetically sealed. The inner fixture 34 is formed of an elliptical plate having the same size as the inner shape of the cylindrical portion 31B of the balloon member 31, and forms a sealed space 38 together with the dome portion 31A of the balloon member 31.

  The outer fixture 35 is formed in an elliptical cup shape that opens upward, so that the inner fixture 34 has a recessed portion 40 that is fitted together with the tube portion 35B of the balloon member 31. By fixing the inner fixing tool 34 by the set screw 41, the inner flange 35C of the balloon member 31 is pressed against the bottom surface of the recessed portion 40. As a result, the sealed space 38 of the balloon member 31 is kept airtight. Such an outer fixing tool 35 is positioned and fixed by engagement between an engaging recess 42 provided on the bottom surface and an engaging portion (not shown) provided on the upper surface of the swinging device 8.

  In FIG. 9, the valve 33 includes a valve main body 53 whose upper end is attached to the inner fixture 34 by screwing and whose lower end is located in a through hole 52 formed in the outer fixture 35. A ball 53, conical coil springs 54 and 55, an exhaust pin 56, a seat 57 and an E ring 58 are incorporated in the main body 53.

  The interior of the valve body 53 is partitioned into two upper and lower chambers 61 a and 61 b by a partition wall 60, and these two chambers are communicated by a central hole 62 provided in the partition wall 60. The ball 53 is housed in the upper chamber 61 a and is normally biased downward by the conical coil spring 54, thereby normally closing the center hole 62.

  The exhaust pin 56 is disposed in the lower chamber 61b so as to be movable up and down, and is normally pressed against the seat 57 by being biased downward by the conical coil spring 55. The upper end of the exhaust pin 56 is inserted into the center hole 62 and faces the ball 53 in close proximity, and the lower end protrudes below the valve body 53.

  The through hole 52 of the outer fixing member 35 is connected to the supply port forming member 71 via an O-ring 72 when compressed air is supplied to the sealed space 38 of the balloon member 31. The supply port forming member 71 is connected to an air supply device (not shown). When the through hole 52 is connected to the supply port forming member 71 and the compressed air A from the air supply device is supplied to the through hole 52, the pressure in the chamber 61b below the through hole 52 and the valve 33 gradually increases. The ball 53 is pushed up against the conical coil spring 54 by the pressure. As a result, the valve 33 is opened, and the compressed air A is supplied to the sealed space 38 of the balloon member 31 through the valve 33 to expand the dome portion 31A. When the center height of the dome portion 31A reaches a desired height, the supply of compressed air is stopped. As a result, the pressure in the lower chamber 61 b is reduced to atmospheric pressure, so that the ball 53 is lowered by the force of the conical coil spring 54 and closes the center hole 62. Thereafter, the fluid supply port forming member 71 is removed from the through hole 52, and the supply of the compressed air to the balloon member 31 is terminated. When the compressed air in the balloon member 31 is removed, the exhaust pin 56 is pushed up against the conical coil spring 55 to lift the ball 53 from the seating surface of the partition wall 60 and open the center hole 62. Good.

  When compressed air is supplied to the sealed space 38 of the balloon member 31 and the dome portion 31A is expanded, the radius of curvature of the cross section including the central axis of the dome portion 31A is minimized in the minor axis direction of the ellipse, and in the major axis direction. A shape close to the maximum toric surface is formed. In this case, since the radius of curvature of the dome portion 31A changes according to the central height (vertex height) of the dome portion 31A, the dome portion 31A is measured and adjusted with an appropriate device. The radius of curvature of the lens 5 can be made close to the shape of the concave surface 5b of the lens 5, but in order to match the shape more accurately, a plurality of types with different major axis and minor axis dimensions or their ratios are prepared. It is preferable to select and use a lens close to the concave shape of the lens 5.

  In the present embodiment, the concave surface 5b is a toric surface, the lens diameter is 65φ, 70φ, 75φ, 80φ (mm), the concave surface 5b has a base curve of 0.00 to 11.25, and an astigmatism range of 0.00 to 4.00. The ratio of the minor axis to the major axis of the balloon member 31 is 0.9, and the major axis dimensions are 65φ, 70φ, 75φ, 80φ, 85φ, 90φ, 95φ, 100φ (mm). And a total of nine types of polishing jigs 9 having a substantially circular balloon member 31 and an outer diameter of 100 mm, and the height of the dome portion 31A of the balloon member 31 and the polishing conditions (pressure, rotation speed, polishing time) Was set as appropriate to perform polishing.

  7, 8, 10, and 11, the polishing pad 10 used for polishing the concave surface 5 b of the lens 5 is made of, for example, a fibrous cloth such as polyurethane, felt, or non-woven fabric, or a synthetic resin. A polishing portion 80 (FIG. 10) formed in an oval shape having a size substantially the same as the front view shape of the dome portion 31A of the balloon member 31 as shown in FIG. The polishing portion 80 is composed of a plurality of fixed pieces 81 extending outward from the periphery. The polishing unit 80 is composed of eight petal pieces 83 that are radially formed by a plurality of grooves 82 that are formed from the outer periphery toward the center. The fixed piece 81 is formed by extending the outer edges of four petal pieces 83 positioned in the major axis direction and the minor axis direction of the eight petal pieces 83 in the radial direction.

  Such a polishing pad 10 is detachably attached to the polishing jig 9 by a fastening member 90 (FIG. 11) formed in a ring shape by a spring material. When attaching the polishing pad 10, first, the polishing portion 80 is placed on the dome portion 31 </ b> A of the balloon member 31. Next, both ends 91a and 91b of the tightening member 90 are sandwiched between the fingertips to narrow the distance between them, so that the diameter of the tightening member 90 is increased. And is bent downward and brought into contact with the outer periphery of the outer fixture 35. When the fingertips are released from both end portions 91a and 91b, the fastening member 90 returns to its original shape and fastens the fixing piece 81 to fix it to the outer periphery of the outer fixture 35, thereby completing the mounting of the polishing pad 10. .

  The lens holder 7 having the lens 5 fixed to the polishing apparatus 1 having such a structure is mounted on the lens mounting portion 6 of the arm 4, and the polishing jig 9 to which the polishing pad 10 is mounted is mounted on the swinging apparatus 8. Then, the lens 5 is lowered by the lifting device 11 and the concave surface 5b is pressed against the surface of the polishing pad 10. In this state, the abrasive is supplied to the surface of the polishing pad 10 and the swinging device 8 is swung and swung while the arm 4 is reciprocated in the left and right and front and rear directions. By these movements, the concave surface 5b of the lens 5 is polished by the polishing pad 10 and the abrasive with a trackless polishing locus in which the polishing locus is slightly shifted every round as shown in FIG. 12 (a) or (b). Finish to the desired surface shape. The polishing allowance is about 5 to 9 μm. As the abrasive, for example, a solution in which an abrasive (abrasive grains) such as alumina oxide or cerium oxide is dispersed in a polishing liquid is used. In polishing, it is desirable to perform polishing twice (rough polishing, final polishing) while changing polishing conditions (abrasive grain size, polishing time).

  As described above, in the lens holding method according to the present invention, seven types of yatoe 13 having different heights and six types of blocking rings 14 having different heights and inner diameters are prepared. A yatoy 13 and a blocking ring 14 having a height corresponding to the height are selected and used, and the center thickness of the alloy 16 is in the range of 1.90 to 3.00 mm, more preferably in the range of 1.9 to 2.5 mm. Therefore, even if the lens has a high refractive index or has a shallow convex curve, the influence of heat and shrinkage of the alloy 16 can be reduced, and the lens power accuracy can be stabilized. Can be maintained.

  In the present invention, since the inner diameter of the blocking ring 14 is set to be approximately equal to the diameter of the lens 5, the alloy 16 is fixed over substantially the entire convex surface 5 a of the lens 5. The boundary between the part that is present and the part that is not adhered can be moved to the vicinity of the outer periphery of the lens 5. Therefore, a polishing mark is not formed on the concave surface at the boundary between the portion where the alloy 16 is bonded and the portion where the alloy 16 is not bonded in the high refractive index lens. Can be produced.

  Further, since the gap between the center of the lens and Yatoi is set in the range of 1.90 to 3.00 mm, and preferably in the range of 1.9 to 2.5 mm, the alloy 16 depends on the type of the lens 5. Therefore, the thermal effect can be further reduced.

In the semi-finished lens of epithio resin (refractive index 1.71), when the center thickness of the lens is about 4.5 mm or less, the influence of heat and shrinkage of the alloy becomes particularly large. Therefore, the change in the surface refractive power of the lens 5 was measured by changing the center thickness of the alloy 16 for a semi-finished lens having a center thickness of 4.5 mm.
Experimental conditions Semi-finished lens: Epithio resin (refractive index 1.71)
Center thickness 4.5mm
BC = 0.80
Diameter 80mm
As Alloy 16, Bi, Pb, Sn, Cd, and In alloy (melting point: 47 ° C.) manufactured by Osaka Asahi Metal Factory Co., Ltd. were used.
Measurement method A Yateo is attached to the convex surface of the semi-finished lens via an alloy, and after the alloy is cooled and solidified, the surface refractive index of the concave surface of the lens is measured, and the change from the surface refractive power of the lens concave surface before the installation of the Yatoi is measured in advance. The rate was determined.

  FIG. 13 is a diagram showing the relationship between the amount of change in the surface refractive power of the concave lens surface and the center thickness of the low melting point alloy. As is apparent from FIG. 13, when the center thickness of the alloy is 3 mm or less, it has been found that the amount of change in refractive power decreases rapidly.

In the above-described embodiment, an example in which the present invention is applied to the lens holder 7 used for the four types of lenses 5 having diameters of 80, 75, 70, and 65 mm has been described, but the present invention is not limited to this. However, the present invention can be similarly applied to other lens diameters.
The lens surface shape is not particularly limited, and may be a spherical surface, a toric surface, an aspherical surface, a non-toric surface, a free curved surface shape such as a progressive multifocal lens, or the like. Moreover, although the grinding | polishing jig | tool demonstrated by the balloon member 31, it is not restricted to this, For example, a metal dish may be sufficient.

  As described above, in the lens holding method according to the present invention, the height of the Yato and the inner diameter and height of the blocking ring are set for each lens having a different diameter and BC, and the gap between the center of the lens and the Yato is 1.90-3. Because it is in the range of 0.000 mm, preferably in the range of 1.9 to 2.5 mm, it is less affected by thermal shrinkage of the low melting point alloy, and the accuracy and stability of the lens power can be improved. In particular, it is suitable for use in polishing lenses that require a high refractive index and a thin wall.

  In the present invention, the inner diameter of the blocking ring is substantially equal to the diameter of the lens, and the entire surface of the convex surface of the lens is held by the low melting point alloy. Even if a polishing mark due to a difference in thermal shrinkage occurs at the boundary with the non-existing part, this polishing mark can be removed when the outer periphery of the lens is removed by edging, so that the optical characteristics are excellent. Enables the production of lenses.

  In addition, the yatoy according to the present invention is provided with a hole on the surface facing the convex surface of the lens so that the opening is inclined near the outer periphery of the yatoi and the inner end is located closer to the center of the yatoi than the opening. The thickness of the center of the melting point alloy is not increased, and the influence of heat and shrinkage can be reduced. Also, the bond strength between the yatoi and the low melting point alloy is large, and the low melting point alloy peels off from the yatoy and rotates or rotates. Can be prevented.

It is a schematic block diagram of the polisher using the lens holding | maintenance method concerning this invention. It is sectional drawing which shows the state which attached the lens holding body to the lens. It is sectional drawing which shows a state when attaching a lens holding body to a lens with a layout blocker. (A), (b), (c) is the top view, sectional drawing, and bottom view of a yatoy. (A), (b) is the top view and AA sectional view taken on the line of a blocking ring. (A)-(d) is a figure which shows the dimensional relationship of the clearance gap between a lens center and the type of a lens, a blocking ring, and a yatoi, and a lens center. It is a top view of a grinding jig. It is the VIII-VIII sectional view taken on the line of FIG. It is sectional drawing of a valve | bulb. It is a top view of a polishing pad. It is a perspective view of the fastening member of a polishing pad. (A), (b) is a conceptual diagram which shows the track-less polishing locus | trajectory of a grinding | polishing apparatus, respectively. It is a figure which shows the relationship between the amount of surface refractive power change of a lens concave surface, and the center thickness of a low melting-point alloy. It is sectional drawing which shows the prior art example of a yatoi.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 2 ... Apparatus main body, 5 ... Lens, 5a ... Convex surface, 5b ... Concave surface, 7 ... Lens holder, 9 ... Polishing jig, 10 ... Polishing pad, 13 ... Yatoi, 14 ... Blocking ring, 16 ... Alloy, 23 ... hole, M ... center thickness of alloy.

Claims (5)

In the lens holding method of fixing the lens to the yatoi through the low melting point alloy by pouring and solidifying a molten low melting point alloy in the space between the convex surface of the lens and the yatoi and the blocking ring,
For each lens specified by the diameter and the convex base curve, a combination of a blocking ring and a yatoy that makes the center thickness of the low melting point alloy within a predetermined range is determined in advance, and based on this predetermined combination Have a process of selecting the blocking ring and yatoy used according to the lens you want to hold,
The predetermined combination of a blocking ring and a yatoy for lenses having the same diameter and different convex base curves is a type of blocking ring or a plurality of types of blocking rings with different heights and a plurality of types of yatoi with different heights. Has been selected from
The plurality of types of blocking rings include a plurality of types of blocking rings having different heights at intervals wider than a predetermined range width of the center thickness of the low melting point alloy,
The plurality of types of yatoys include a plurality of types of yatoi having different heights at intervals equal to or less than a range width of a predetermined range of the center thickness of the low melting point alloy,
A lens holding method. The lens holding method according to claim 1,
The types of yatoi having different heights used in the combination of the predetermined blocking ring and yatoy for lenses having the same diameter and different convex base curves are more than types of blocking rings having different heights. A lens holding method. The lens holding method according to claim 1 or 2,
The blocking ring used in the predetermined combination of the blocking ring and the yatoy for lenses having the same diameter and different convex base curves is one type of blocking ring or two types of blocking rings having different heights. A lens holding method. The lens holding method according to any one of claims 1, 2, and 3,
The plurality of different types of Yatoi used in the predetermined combination of the blocking ring and the Yatoi for lenses having the same diameter and different convex base curves have a range of a predetermined range of the center thickness of the low melting point alloy. A lens holding method comprising a plurality of types of Yatoi having different heights at a constant interval as described below.   A step of cutting or polishing a surface opposite to the side where the spectacle lens is held in a state where the spectacle lens is held by the lens holding method according to claim 1. A method of manufacturing a spectacle lens characterized by the above.

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