JP2011173204A - Method for manufacturing optical lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for obtaining an optical lens having a desired optical surface by polishing a surface to be polished of a variety of surface shapes without large variation in a polishing amount within the surface. <P>SOLUTION: The method for manufacturing an optical lens includes relatively moving a polishing tool having a projection formed of an elastic material and a molding formed into a lens shape having a concave surface while supplying polishing agent to a gap between the projection of the polishing tool and the concave surface of the molding and thereby polishing the concave surface. As the polishing tool, a polishing tool satisfying (1) and (2) below is to be selectively used. (1) The polishing tool has such a shape that, when the projection of the polishing tool is fitted with the concave surface of the molding of a polishing object, the both contact with each other in the center part, however they separate from each other in the peripheral part. (2) When the projection of the polishing tool is fitted with the concave surface of the molding of the polishing object in a state a reference axis on the concave surface and a reference axis on the projection oppose with each other, the separation distance in the peripheral part is a predetermined allowable separation distance or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical lens, and more particularly to a method for manufacturing an optical lens, including creating an optical surface by polishing a concave surface.

  In the manufacturing process of optical lenses such as eyeglass lenses, lenses that are thicker than the finished dimensions (semi-finished products) are mass-produced and stored, and after receiving orders, product lenses that have the desired optical characteristics according to user needs Finishing (finished product) is widely performed. Usually, in this semi-finished product, the object side surface is finished to an optical surface by transferring the mold surface during cast polymerization. On the other hand, the eyeball side surface (concave surface) is processed into a desired surface shape according to the lens prescription by machining (grinding or cutting). However, in the state as it is, since machining traces remain on the concave surface, it cannot be used as an optical lens. Therefore, usually, after the machining, polishing is performed. Through this polishing process, a product lens whose both surfaces are finished to a desired optical surface can be obtained.

  Conventionally, in the above polishing process, the sliding polishing using a metal polishing dish having a convex surface that coincides with the surface to be polished (concave surface) has been performed. Rubbing and polishing with a metal polishing dish has the advantage of easily obtaining an optical surface without damaging the surface shape formed by cutting due to good shape accuracy, but it can handle lens prescription for each lens prescription If the surface to be polished has a complex surface shape including astigmatism components and progressive elements, a polishing plate that can handle this is processed from a metal material. There was a problem that it was difficult.

  In contrast, in recent years, instead of a metal polishing dish, an elastic abrasive body having a convex polishing portion is pressed against a surface to be polished, and an abrasive is interposed between the polishing body and the surface to be polished. Polishing the surface to be polished by moving is widely performed (for example, see Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2004-261554 JP 2008-183714 A

The above method can polish even when the convex shape of the polishing jig does not completely correspond to the concave shape of the surface to be polished because the elastic polishing body is slightly deformed when pressed against the surface to be polished. . Therefore, since the number of items that can be handled by one polishing body increases, the number of polishing jigs to be prepared can be greatly reduced as compared with a method using a metal polishing dish.
However, as a result of the study by the inventors of the present application, it has been clarified that the amount of polishing varies in the plane in the method using the elastic polishing body. In particular, it has been found that on the astigmatic axis of the astigmatic lens, there is a large amount of unpolished peripheral portion and there is a large variation in the polishing amount.

As described above, in the conventional polishing method, variation in the polishing amount is observed in the surface, but in the surface formed into a desired surface shape by machining, the optical surface that is finally obtained as the variation in the polishing amount is larger Therefore, it is desirable to increase the uniformity of the polishing amount in the plane.
SUMMARY OF THE INVENTION An object of the present invention is to provide means for obtaining an optical lens having a desired optical surface by polishing a surface to be polished having various surface shapes without large variations in the amount of polishing in the surface.

The inventor of the present application examined the distribution of the polishing amount on the surface to be polished in order to achieve the above object, and in a normal polishing process, the polishing amount at the central portion is large and the polishing amount at the peripheral portion is small. It was observed. This is because an elastic polishing body having a convex polishing portion tends to concentrate pressure on the central portion when it is slid while pressed against the surface to be polished.
Therefore, as a countermeasure, the curvature of the polished surface is increased with respect to the surface to be polished so that the peripheral portion of the polished surface is brought into contact with the surface to be polished with priority over the center (hereinafter, this state is referred to as “outer contact”). It is possible. A schematic diagram of this state is shown in FIG. In this outer periphery state, it is expected that the variation in the polishing amount within the surface to be polished will be reduced as a result of the reduction in the polishing amount in the central portion and the increase in the polishing amount in the peripheral portion. However, according to the study by the present inventor, contrary to expectation, the in-plane polishing amount variation could not be reduced.
Based on the above findings, the inventor of the present application has made further studies, and as a result, has obtained the following new findings.
(1) As an elastic polishing body, when the curvature of the polishing surface is small with respect to the surface to be polished, it is brought into contact with the surface to be polished and the peripheral portion is separated (hereinafter this state is referred to as “medium”) ), It is possible to reduce the variation in the amount of polishing in each part of the surface to be polished. FIG. 1B is a schematic diagram of the middle state. The reason why the polishing amount is made uniform by setting the center in this way is that there is a gap to some extent and the ease of movement of the abrasive is ensured between the polishing jig and the surface to be polished. It is presumed that it contributes to increase the polishing efficiency by the intervening abrasive. Conventionally, the surface of the polishing jig has been made to substantially match the curvature of the surface to be polished even when an elastic polishing body is used, so it is possible to reduce the variation in polishing amount by forming a gap at the periphery. Is a new fact found by the present inventors.
(2) However, if the amount of separation at the peripheral portion exceeds the allowable amount that can be polished, it becomes difficult to polish the peripheral portion of the surface to be polished. Therefore, the amount of separation at the peripheral portion needs to be within a predetermined range. is there. The amount of separation allowed here is determined by the combination of the surface to be polished and the surface of the polishing jig.
The present invention has been completed based on the above findings.

That is, the above object was achieved by the following means.
[1] While supplying a polishing agent between a convex portion of a polishing jig and a concave surface of a molded body, a polishing jig having a convex portion made of an elastic material and a molded body molded into a lens shape having a concave surface. A method of manufacturing an optical lens comprising polishing the concave surface by relatively moving,
A method for producing an optical lens, wherein a polishing jig satisfying the following (1) and (2) is selected and used as the polishing jig.
(1) When the convex part of the polishing jig is fitted to the concave surface of the molded object to be polished, it has a shape that comes into contact with the central part but separates at the peripheral part.
(2) When the polishing jig convex part is fitted in a state in which the concave surface of the molded object to be polished is opposed to the reference axis on the concave surface and the reference axis on the convex part, the separation distance at the peripheral part is set in advance. Or less than the allowable separation distance.
[2] The method for manufacturing an optical lens according to [1], wherein the reference axis on the concave surface is set in an axial direction that minimizes the average curvature on the concave surface.
[3] The method for manufacturing an optical lens according to [1] or [2], wherein a reference axis on the convex portion of the polishing jig is set in an axial direction that minimizes an average curvature on the convex surface.
[4] The method for manufacturing an optical lens according to any one of [1] to [3], wherein the relative movement is performed in a state where a reference axis on the concave surface and a reference axis on the convex portion are substantially parallel. .
[5] The optical lens manufacturing method according to any one of [1] to [4], wherein the reference axis on the concave surface is an astigmatic axis of the astigmatic lens.
[6] The method for manufacturing an optical lens according to any one of [1] to [5], wherein the allowable separation distance is set in a range of 1 to 8 mm.

According to the present invention, in the surface to be polished having various surface shapes, it is possible to reduce the variation in the polishing amount in the surface. As a result, the optical surface can be formed while maintaining the surface shape formed by machining. Moreover, since the shape maintenance accuracy in polishing is high, the influence on the optical performance due to polishing can also be reduced. As a result, it is possible to suppress the occurrence of frequency defects.
In addition, when there is a large amount of variation in the polishing amount in the surface, it is necessary to perform polishing again by changing the polishing conditions in order to selectively polish the unpolished portion. Since the variation can be reduced, the number of polishing steps can be reduced, and the working efficiency can be greatly improved.

It is the schematic which shows the example of arrangement | positioning of a to-be-polished surface and a grinding | polishing jig | tool. FIG. 1A shows a middle hit state, and FIG. 1B shows an outer hit state. It is a schematic block diagram of the polisher which can be used in this invention. It is sectional drawing which shows the state which attached the lens of grinding | polishing object to the lens holding body. It is explanatory drawing of the swing rotation motion of a rocking | fluctuation apparatus and a grinding | polishing jig | tool. It is a top view which shows an example of a grinding | polishing jig | tool. It is a top view which shows the state which attached the polishing pad to the grinding | polishing jig | tool shown in FIG. It is a bottom view which shows an example of a grinding | polishing jig | tool. It is the XII-XII sectional view taken on the line of FIG. It is a figure which shows an example of the movement locus | trajectory of the lens of grinding | polishing object. The evaluation result of an Example is shown.

The present invention provides a polishing jig having a convex portion made of an elastic material and a molded body molded into a lens shape having a concave surface by supplying an abrasive between the convex portion of the polishing jig and the concave surface of the molded body. The present invention relates to a method of manufacturing an optical lens including polishing the concave surface by relatively moving the surface. In the optical lens manufacturing method of the present invention, a polishing jig satisfying the following (1) and (2) is selected as a polishing jig used for polishing.
(1) When the convex part of the polishing jig is fitted to the concave surface of the molded object to be polished, it has a shape that comes into contact with the central part but separates at the peripheral part.
(2) When the polishing jig convex part is fitted in a state in which the concave surface of the molded object to be polished is opposed to the reference axis on the concave surface and the reference axis on the convex part, the separation distance at the peripheral part is set in advance. Or less than the allowable separation distance.
According to the present invention, by using the polishing jig satisfying the above (1) and (2), variation in the polishing amount in the surface can be suppressed, and thereby the surface shape formed by machining is maintained. Thus, an optical lens having a desired optical surface can be obtained.
Hereinafter, the manufacturing method of the optical lens of the present invention will be described in more detail.

Polishing jig The polishing jig used in the present invention has a convex portion made of an elastic material. As described above, using a polishing jig made of an elastic material can greatly reduce the number of polishing jigs to be prepared as compared with a polishing method using a metal polishing dish, so that the cost and This is extremely advantageous in terms of production efficiency.

  As the polishing jig, one having the entire convex portion made of an elastic material can be used, or the convex portion is a balloon member having a cavity (hollow structure) inside, and a fluid is supplied to the cavity. A polishing jig that can perform polishing while applying tension to the balloon member can also be used. The latter polishing jig is advantageous in improving the shape accuracy because the polishing conditions can be controlled by the pressure applied by the fluid.

  The elastic material preferably has a property as an elastic body and has a hardness of about 5 to 70 as defined by JIS k 6253 (durometer type A or type E). Specific examples include natural rubber, synthetic rubber such as styrene butadiene rubber (SBR) and silicon rubber. The balloon member preferably has an elastic material portion with a thickness of about 1 to 10 mm. As the fluid supplied to the balloon member, liquids such as compressed air, nitrogen and water are usually used. Regarding the specific configuration of the polishing jig including the balloon member, reference can be made to, for example, paragraphs [0033] to [0037] of Japanese Patent Application Laid-Open No. 2004-261554, paragraphs [0036] to [0057] of Japanese Patent Application Laid-Open No. 2008-283714, and the like. .

The surface shape of the convex portion of the polishing jig can be any shape such as a spherical surface, an elliptical shape in plan view, an aspherical surface, a toric surface, an atoric surface, a free-form surface, or a curved surface obtained by combining these. Moreover, it is preferable that the convex surface has a larger area than the surface to be polished because of high polishing efficiency.
As will be described later, in the present invention, a reference axis is set on each of the convex surface of the polishing jig and the surface to be molded, and the polishing jig is selected based on the distance between the reference axes. From the viewpoint of ease of setting the reference axis at this time, and also from the viewpoint of ease of setting for performing polishing with the reference axes facing each other as will be described later, the surface shape of the convex portion of the polishing jig Is preferably a surface shape having two axial directions that are perpendicular to each other, such as a toric surface or an atoric surface, with different average curvatures in the surface, and a reference axis is preferably set in at least one of these two axial directions. More preferably, the reference axis is set in each of these two axial directions.
Note that it is conceivable that the convex portion of the polishing jig has a surface shape with a constant curvature within the surface, such as a spherical surface, which is suitable when the object to be polished is a spherical surface. However, in an astigmatic lens or a progressive addition lens with a large addition, there is a large difference in curvature in the surface on the concave surface to be polished. For this reason, if the curvature of the surface of the convex portion of the polishing jig is constant, the fitting between the polishing jig and the surface to be polished is greatly different in each part of the surface. It is inferred that this is the reason why the polishing amount variation was particularly large on the astigmatic axis of the astigmatic lens in the conventional polishing method. On the other hand, if a difference in curvature is provided within the surface of the polishing jig convex surface, the fitting with the surface to be polished having a difference in curvature within the surface can be made uniform as described above. Here, if one (or more) representative of the in-plane curvature is selected as the reference axis, and a polishing jig is selected based on the state of separation from the surface to be polished on the reference axis, It becomes possible to select a polishing jig with good fitting.

  During polishing, a polishing pad is usually disposed on the convex portion of the polishing jig. This polishing pad plays a role of holding an abrasive and increasing polishing efficiency. Although it does not specifically limit as a polishing pad, For example, what uses fibrous cloth, synthetic resins, etc., such as foaming polyurethane, felt, a nonwoven fabric, and wool, can be used. In the present invention, since a polishing jig in which a predetermined gap is formed between the surface to be polished is selected and used, a polishing pad having a thickness within a range in which the correspondence of the shape is not greatly impaired by the polishing pad is used. It is preferable to do. Specifically, the thickness of the polishing pad is preferably about 0.5 to 3.0 mm. Regarding the shape and arrangement method of the polishing pad, for example, paragraphs [0034] of JP-A-2004-261904, paragraphs [0026] to [0027], [0058] to [0061] of JP-A-2008-183714, etc. You can refer to it.

The molded object to be polished is a lens having a concave surface, and can be a so-called semi-finished product. The molded body can be obtained by a known molding method such as a casting polymerization method. Although it does not specifically limit as a raw material, For example, various resin normally used for plastic lenses, such as a urethane type, an epithio type | system | group, a polycarbonate type, diethylene glycol bisallyl carbonate (CR39), can be mentioned.

  As described above, the concave surface of the semi-finished product is machined according to the lens prescription. By this machining, a spherical surface, an aspherical surface, a toric surface, an atoric surface, a free-form surface including a progressive element or a progressive surface, or a curved surface obtained by combining these is formed. The machining can be performed by known grinding and / or cutting. As an example, cutting by a curve generator that performs three-dimensional NC control can be cited.

Selection of Polishing Jig In the present invention, as a polishing jig used for polishing, a polishing jig that satisfies the relationship (1) and (2) above with respect to the shape of the surface to be polished is selected. Whether or not a certain polishing jig satisfies the above (1) and (2) can be confirmed visually by actually combining the polishing jig and the molded object to be polished, or This can be confirmed by calculating the separation distance from the design value of each polishing jig.
Hereinafter, the conditions (1) and (2) will be described in more detail.

  Condition (1) prescribes that the surface to be polished and the convex portion of the polishing jig have an intermediate relationship. Here, the central portion where both are in contact can be, for example, the geometric center of the surface to be polished and the surface of the convex portion or the vicinity thereof. In the conventional polishing method, the amount of polishing in this portion is larger than that in the peripheral portion, which is a cause of variation in the amount of polishing in the surface. On the other hand, according to the present invention, by performing polishing with a combination of a polishing jig and a surface to be polished that realizes the middle relation, variation in the polishing amount between the central portion and the peripheral portion can be reduced. The polishing jig convex part may be in a state of being separated from the surface to be polished over the entire periphery of the peripheral part, or may be in contact with the surface to be polished in a part of the peripheral part. Preferably, in the conventional method, it is preferable that the surface of the convex portion and the surface to be polished are separated from each other at the peripheral portion in the axial direction where the variation in polishing amount is large. In the conventional method, the axial direction in which the variation in the polishing amount is large will be described later.

  However, as described above, if the separation distance at the peripheral portion is excessively increased, it becomes difficult to polish the peripheral portion. Therefore, in the present invention, the separated state between the surface to be polished and the surface of the convex portion is defined by the condition (2) within an allowable range for polishing. This polishable separation range (allowable separation distance) is determined by the combination of the surface to be polished and the surface of the polishing jig, and is preferably set by conducting a preliminary experiment. However, under general polishing conditions, for example, 1 mm About 11 mm, and further about 1-8 mm are preferable.

  The condition (2) is most preferably satisfied over the entire surface of the surface to be polished and the surface of the convex portion. However, in selecting a polishing jig to be used, obtaining the separation distance over the entire surface results in enormous measurement points. It is difficult for practical use. Therefore, in the present invention, a reference axis is set for each of the surface to be polished and the surface of the convex portion, and the polishing jig is selected using as an index the separation distance in a state where both axes are opposed to each other. Here, it is preferable to set the reference axis in the axial direction in which the polishing amount varies greatly in the conventional polishing method in order to increase the in-plane uniformity of the polishing amount. According to the inventor's study, in the conventional polishing method, when the surface to be polished has an in-plane curvature distribution, the amount of polishing at the peripheral portion is smaller in the axial direction where the average curvature is smaller, and the amount of polishing varies in the surface. A tendency to occur was observed. For example, in an astigmatic lens having a concave surface made of a toric surface, the base direction (astigmatic axis direction) on the concave surface is an axial direction in which the average curvature is the smallest in the surface, and conventionally, the amount of polishing varies in this axial direction. In particular, there was a tendency that unpolished portions of the peripheral portion were liable to occur. Also, in the progressive addition lens, when the difference in the addition power is large, the difference in curvature between the distance portion and the near portion is large, so that the peripheral edge portion is left unpolished in the axial direction where the average curvature is minimum in the plane. Tended to occur. Therefore, in the present invention, the reference axis on the surface to be polished is preferably set in the axial direction in which the variation in the polishing amount is large as described above and the average curvature is minimum in the surface. Further, the reference axis on the surface to be polished is not limited to one, and may be two or more. For example, when two reference axes are set, from the viewpoint of ease of setting the reference axis, it is preferable to set the axial direction in which unpolishing is likely to occur as described above and the axial direction perpendicular thereto. Alternatively, as the reference axis representing the in-plane shape, the second reference axis is the axial direction having the largest shape difference from the axial direction having the largest variation in polishing amount, that is, the axial direction having the maximum average curvature in the plane. It is also preferable to set to.

  Hereinafter, as an example, an astigmatic lens and a progressive power lens will be described as an example. A so-called cross direction orthogonal to this is an axial direction (maximum curvature direction) in which the average curvature is maximum in the plane. Therefore, it is preferable to set the reference axis on the concave surface in the astigmatic lens in the minimum curvature direction (base direction) and the maximum curvature direction (cross direction). In the progressive-power lens, it is preferable to set the reference axis in the axial direction in which the average curvature is minimum and the maximum axial direction in the plane.

From the point of fitting between the surface of the convex part of the polishing jig during polishing and the surface to be polished, if the reference axis on the concave surface is set in the axial direction that minimizes the average curvature in the plane, the convex part of the polishing jig The reference axis on the surface is also preferably set in the axial direction that minimizes the average curvature on the convex surface. Similarly, when the reference axis on the concave surface is set in an axial direction that maximizes the average curvature in the surface, the reference axis on the polishing jig convex portion also has the maximum average curvature on the convex portion surface. It is preferable to set in the axial direction. In addition, the average curvature in each axial direction on a certain surface can be determined based on the lens prescription value and the design value of the polishing jig. Alternatively, the average curvature in each axial direction on a certain surface can be determined by the method described in paragraphs [0023] to [0059] of Japanese Patent No. 4199723 or a method based thereon.
As described above, the mode in which one or two reference axes are set on the surface to be polished has been described, but it is of course possible to set three or more reference axes.

Polishing Method Next, a method of polishing the surface to be polished using a polishing jig that satisfies the above (1) and (2) with respect to the shape of the concave surface (surface to be polished) of the molded body to be polished will be described. .
At the time of polishing, as described above, by moving (sliding) both surfaces relatively with the polishing pad convex portion pressed against the surface to be polished with the polishing pad placed on the normal polishing jig convex portion. The surface to be polished is polished. Here, during polishing, an abrasive is supplied between the convex portion of the polishing jig and the concave surface of the molded body. As a polishing agent, a commercially available slurry that is usually used for polishing treatment can be used. Alternatively, a slurry prepared by dispersing abrasive grains such as alumina and diamond powder in water or an aqueous solvent can be used.

  The operation of the polishing jig at the time of polishing and the molded object to be polished can be the same as the normal polishing process, but in order to accurately realize the separation distance set at the peripheral edge in the actual polishing process In the selection of the polishing jig, it is preferable to perform the polishing while maintaining the direction of the axes as the reference axes to be constant, and specifically, the polishing jig and the object to be polished so that the reference axes are substantially parallel to each other. It is preferable to reciprocate one or both of the molded bodies back and forth or left and right. In order to perform such an operation, the polishing jig and the molded object to be polished are placed in the polishing apparatus so that the reference axes face each other, and then the polishing jig convex portion is pressed against the surface to be polished (concave surface). In this state, the polishing jig convex portion is swung and swung, and the molded body is reciprocated in the direction of the reference axis of the concave surface. It is preferable to polish.

An example of a polishing apparatus capable of the above operation will be described below with reference to the drawings.
FIG. 2 is a schematic configuration diagram of a polishing apparatus used in such a polishing method that can be used in the present invention.
In the figure, a polishing apparatus generally indicated by reference numeral 30 has an apparatus main body 32 installed on the floor, and a horizontal axis 33 that can move in the left-right direction (arrow X direction) on the apparatus main body 32 in the drawing. An arm 34 rotatably disposed in a direction orthogonal to the paper surface (arrow AB direction), and a drive device (not shown) that reciprocates the arm 34 in the left-right direction and rotates in a direction orthogonal to the paper surface, A lens mounting portion 36 provided on the arm 34 for holding the convex surface 2a of the lens 1 via a lens holding body 37, and disposed in the apparatus main body 32 so as to be positioned below the lens mounting portion 36, not shown. A swinging device 38 that swings (does not rotate) around a vertical axis K by a driving device is provided. Further, a polishing jig 39 detachably provided on the rocking device 38, a polishing pad 40 detachably attached to the polishing jig 39, an elevating device 41 for raising and lowering the lens attaching portion 36, and the like are provided. ing. Such a polishing apparatus 30 is described in, for example, Japanese Patent Application Laid-Open No. 2008-183714.

  The surface 2b to be polished is machined into a predetermined surface shape by a curve generator or the like that performs three-dimensional NC control in advance.

FIG. 3 is a cross-sectional view showing a state in which the lens is attached to the lens holder 37.
In the figure, a lens holder 37 that holds the lens 1 is composed of a metal (tool steel, etc.) yatoi 44 and an adhesive 45 that joins the yatoi 44 and the lens 1. A fitting recess 47 that fits into the lens mounting portion 36 is formed on the back side of the yatoi 44. The fitting recess 47 has a hame-eye orientation. As the adhesive 45, an alloy having a low melting point (for example, an alloy of Bi, Pb, Sn, In, and Ga, a melting point of about 49 ° C.) is used. A scratch-preventing protective film 46 is interposed between the convex surface 2 a of the lens 1 and the adhesive 45. In order to join the lens 1 to the Yatei 44 with the adhesive 45, for example, a device called a layout blocker manufactured by LOH is used. The lens 1 is attached to the yatoi 44 in consideration of the position of the reference axis described above. Specifically, the lens 1 is attached to the yatoy 44 so that the reference axis direction of the surface to be polished 2 b coincides with the reference axis of the polishing jig 39 when the yatoy 44 is attached to the lens attachment portion 36. As the Yatoi 44, those having different sizes according to the power of the lens 1, the outer diameter, and the curvature of the convex surface 2a are used.

  In FIG. 2, the swinging device 38 is attached to the upper end of the vertical rotating shaft 21 at a required angle (α) in the vertical direction, and the polishing jig 39 is detachably installed on the upper end surface. Yes. The rotating shaft 48 rotates around the axis during polishing. The swinging device 38 is configured to swing around the axis of the rotating shaft 48 when the rotating shaft 48 rotates. The inclination angle α of the swing device 38 with respect to the rotation shaft 48 is, for example, 5 °. FIG. 4 shows the locus 50 of the swinging movement of the swinging device 38 and the polishing jig 39. The oscillating device 38 only revolves around the rotation shaft 48 in the swinging and swinging motion, and does not rotate.

  5-8, the said grinding | polishing jig | tool 39 obstruct | occludes the lower surface side opening part of this balloon member 51 which the lower surface side formed in the cup shape with the elastic material open | releases, and hold | maintains the inside airtightly. The fixture 52 and a valve 53 for supplying compressed air to the balloon member 51 are configured.

  The balloon member 51 is integrally extended to a dome portion 51A, a substantially elliptical cylindrical portion 51B integrally extending downward from the outer periphery of the dome portion 51A, and a lower end of the cylindrical portion 51B. It is comprised with the cyclic | annular inner flange 51C.

  The fixing member 52 is composed of two members, an inner fixing member 55 and an outer fixing member 56. By sandwiching the inner flange 51C of the balloon member 51 from the inner side and the outer side by these members, the lower surface side opening of the balloon member 51 is hermetically sealed. Is sealed. For this reason, a sealed space 57 is formed inside the balloon member 51. The inner fixture 55 is formed of an elliptical plate having the same size as the inner shape of the cylindrical portion 51B of the balloon member 51, and an annular groove 58 into which the inner flange 51C is fitted is formed on the outer peripheral portion of the lower surface.

  The outer fixture 56 is formed in a cup shape that opens upward, and thus includes a disk-shaped bottom plate 56A and a cylindrical portion 56B that protrudes integrally from the outer periphery of the upper surface of the bottom plate 56A. The inner fixture 55 is fitted and inserted into the cylindrical portion 56 </ b> B together with the cylindrical portion 51 </ b> B of the balloon member 51. The cylindrical portion 56 </ b> B has a circular outer shape, and an inner shape is formed in an elliptical shape having substantially the same size as the outer shape of the cylindrical portion 51 </ b> B of the balloon member 51. Then, after the inner fixing device 55 is integrally coupled by a plurality of set screws 60, the outer fixing device 56 is placed on the upper surface of the swinging device 38 in the reference axial direction of the balloon member 51 (the arrow in FIG. 5). F direction) is attached so as to coincide with the reciprocating movement direction (X direction in FIG. 2) of the arm 34, which is the reference axis direction of the polished surface 2b.

  The valve 53 is a check valve and is attached to the inner fixture 55.

  When compressed air is supplied to the sealed space 57 of the dome member 51 through the valve 53, the dome portion 51A expands upward, and the average curvature of the cross section including the central axis of the dome portion 51A is in the minor axis direction (FIG. 5). The toric surface is maximum in the direction of arrow G) and minimum in the long axis direction (direction of arrow F). In this case, since the curvature of the dome portion 51A changes corresponding to the center height (vertex height) of the dome portion 51A, the dome portion 51A is measured and adjusted with an appropriate device to measure the height of the dome portion 51A. Can be set to a desired curvature.

  The polishing pad 40 is detachably attached to the polishing jig 39 by the fastening member 76. The fastening member 76 is obtained by plastically deforming a wire spring having an appropriate thickness into a ring shape and superimposing both ends, and has a diameter smaller than the outer diameter of the outer fixture 56 in a natural state. The portions 76a and 76b are bent outward at substantially right angles.

  In order to attach the polishing pad 40 to the polishing jig 39, first, the dome portion 51A of the balloon member 51 is expanded into a predetermined dome shape by supplying compressed air, and then the polishing portion 70 of the polishing pad 40 is mounted thereon. Put. Next, both ends 76a and 76b of the tightening member 76 are sandwiched between fingertips, and the distance between the end portions 76a and 76b is narrowed against elasticity, so that the tightening member 76 is expanded in diameter. The fixing pieces 71 are pressed from above, and the fixing pieces 71 are bent downward and brought into contact with the outer periphery of the outer fixture 56. When the fingertips are released from both end portions 76a and 76b, the fastening member 76 returns to its original shape, and the fixing piece 71 is fastened and fixed to the outer periphery of the outer fixing tool 56, whereby the attachment of the polishing pad 40 is completed.

The lens 1 is polished by the polishing apparatus 30 having such a structure according to the following procedure.
First, the lens 1 is mounted on the lens mounting portion 36 of the arm 34 via the lens holder 37. Next, a polishing jig 39 to which a polishing pad 40 is attached is installed on the upper surface of the rocking device 38. When the lens 1 is attached to the lens attaching portion 36, the lens 1 is attached so that the reference axis direction of the polished surface 2b of the lens 1 coincides with the reciprocating direction of the arm 34 (the arrow X direction in FIG. 2). When the polishing jig 39 is installed on the rocking device 38, the reference axis direction (F direction) of the balloon member 51 is set to coincide with the reciprocating movement direction (arrow X direction) of the arm 34.

  When the lens 1 is attached to the lens attachment portion 36, the lens 1 is lowered by the elevating device 41, and the concave surface 2 b is pressed against the surface of the polishing pad 40. In this state, an abrasive is supplied to the surface of the polishing pad 40, and the arm 34 is reciprocated in the left-right direction and rotated in the front-rear direction around the shaft 33. The movement trajectory of the lens 1 due to the movement of the arm 34 is shown in FIG.

Further, as the rotating shaft 21 rotates, the swinging device 38 is swung as shown in FIG. By such movement of the lens 1 and the swinging device 38, the concave surface 2b of the lens 1 is polished by the polishing pad 40 and the abrasive with a trackless polishing locus in which the polishing locus is slightly shifted every round, and a desired toric surface is obtained. Finish.
When two reference axes are set, in addition to the movement of the arm 34 in the left-right direction (arrow X direction), a direction (arrow AB direction) perpendicular to the paper surface with the horizontal axis 33 of the arm 34 as the center. ) Is used in the state where the directions of the two reference axes on the convex surface and the two reference axes on the concave surface are kept constant in the respective directions. be able to.

  Polishing of the concave surface of the molded body may be performed by one-step polishing or may be performed by two-step polishing or more. The concave surface cut by the curve generator may contain a machining step due to backlash by NC control. In that case, it is necessary to remove the machining step by polishing to obtain an optical surface. There is. Therefore, in this case, it is preferable that the concave surface polishing step is a two-step polishing of rough polishing and final polishing. For example, in rough polishing, polishing abrasive grains having an average particle diameter of 1.6 to 1.8 μm can be used, and the temperature can be controlled to 8 to 14 ° C. for polishing. The polishing time can be 2 to 6 minutes, the polishing pressure can be 5 to 400 mbar, and the rotation speed can be 400 to 1000 rpm.

  Next, in the finish polishing, for example, polishing can be performed using a polishing abrasive having an average particle size of about 0.8 μm. The polishing time can be about 30 seconds to 1 minute, the polishing pressure can be 5 to 400 mbar, and the rotation speed can be 400 to 1000 rpm. In this way, the polishing step can be reliably removed by changing the polishing conditions.

  According to the present invention described above, in the surface to be polished having various shapes, it is possible to reduce the variation in the polishing amount in the surface, and thus it is possible to perform polishing while maintaining the surface shape formed by machining. it can. Thereby, according to this invention, the optical lens which has a desired optical surface can be obtained.

  In the following, the present invention will be further illustrated by examples. However, the present invention is not limited to the embodiment shown in the examples.

1. Molding of Lens to be Polished (Astigmatic Lens) A semi-finished lens made of polycarbonate having one convex surface and the other concave surface was cast by a casting polymerization method. The concave surface is a toric surface, and the base direction (astigmatic axis direction) is the direction in which the average curvature is minimum in the plane, and the cross direction orthogonal to this is the direction in which the average curvature is maximum in the plane. The curvature radius in the base direction (astigmatic axis direction) of the concave lens surface was 120.188 mm, and the curvature radius in the cross direction perpendicular thereto was 91.891 mm.

2. Concavity machining 1. The concave surface of the semi-finished lens molded in step 1 was cut into a predetermined surface shape by a curve generator that performs three-dimensional NC control (processing accuracy within 3 μm, surface roughness Ry 0.3 to 0.5 μm).

3. Production of a polishing jig As a test polishing jig, a polishing jig having the structure shown in FIGS. 5 to 8, in which the dome portion 51A is a toric surface and the height in the base direction and the cross direction (sag. Values) are different. A plurality of types were produced. As the balloon member, SBR having an outer diameter of 90 mm, a hardness defined by JIS k6253 (durometer type E), and a material thickness of about 3 mm was used.

4). Implementation of polishing process 2. And the lens subjected to the cutting process in 3 above and 3. 2-4 is attached to the polishing apparatus shown in FIGS. 2 to 4, and an alumina having an average particle size of 0.8 μm as an abrasive is dispersed in water with a polishing time of 5 minutes, a polishing pressure of 200 mbar, a rotation speed of 530 rpm. Polishing was performed using the obtained slurry. Mounting to the polishing device is performed so that the base direction of the surface to be polished and the base direction of the surface of the dome part match, and the cross direction of the surface to be polished and the cross direction of the surface of the dome part coincide with each other. Polishing was performed so that the substantially coincident relationship between the directions and the cross directions was located. A polishing pad made of wool having a thickness of about 2 mm was used as the polishing pad.

5. Evaluation of lens after polishing 4. The surface properties, polishing allowance, and optical performance of the concave surface subjected to the polishing process were evaluated by the following methods.
(1) Surface properties (variation of in-plane polishing amount)
Observation of reflected light and transmitted light by visual observation and transmission inspection using a high-intensity lamp were used in combination to evaluate the surface properties (whether or not the surface properties were reduced due to variations in the in-plane polishing amount).
(2) Polishing allowance The change in thickness of the central portion before and after polishing was measured. In this example, when the measured change in thickness was 5 μm or less, it was determined that the polishing removal allowance evaluation result was good.
(3) Optical performance Using an optical measuring device for eyeglasses (lens meter), the presence or absence and degree of errors from design values (S frequency, C frequency, prism) at various optical measurement points were evaluated.

6). Evaluation results In the combination of the polishing jig and the lens evaluated above, when the concave surface, which is the surface to be polished, and the dome surface contact at the center (geometric center) on the reference axis and are separated at the peripheral edge, the polishing treatment is performed. The position of φ75 mm on the surface of the dome portion of the tool is the position where the separation distance is maximized. Therefore, the distance from the concave surface in the base direction and the cross direction was determined from the design value at a position of φ75 mm on the surface of the dome. The numerical value shown in FIG. 10 is the separation distance thus obtained. For example, (8-0) in the upper right column means that the separation distance in the base direction is 8 mm and the separation distance in the cross direction is 0 mm (= contact). Show. The same applies to the other columns. In the column, a negative value indicates a shape in which the peripheral edge is separated with priority over the center, that is, the outer periphery. The column (0-0) is in a state where the concave surface and the dome surface have the same shape, and the sag. Value in this state was 2 mm in the base direction and 4 mm in the cross direction. 5. above. As a result of confirming the correspondence between the evaluation results and the maximum separation distance, the following results were obtained.
In a combination in which the relationship between the surface of the polishing jig convex portion and the surface to be polished is the outside in the base direction and the cross direction, an unpolished region is generated in the region of the outer peripheral portion of 2 to 4 mm compared to the peripheral portion. The amount of polishing at the center portion increased, and as a result, the evaluation result of the surface property was inferior.
On the other hand, in the combination in which the relationship between the surface of the polishing jig convex portion and the surface to be polished is the middle in the base direction and the cross direction, the base direction of the surface to be polished and the axis in the cross direction are higher than the above relationship The amount of polishing was small and uniform polishing was possible. Especially, in the base direction and the cross direction, those with a maximum separation distance of 2 to 5 mm (within the thick frame in FIG. 10) have good evaluation results in any of the surface properties, polishing allowance, and optical performance. Met.
From the above results, if the maximum separation distance is in the range of 2 to 5 mm in both the base direction and the cross direction, a desired optical surface with good surface properties and optical performance can be formed with an appropriate polishing allowance. It can be confirmed that Therefore, according to this evaluation, by selecting the one having a relationship between the surface to be polished and the middle surface and having the maximum separation distance between the surface to be polished and the surface of the dome within a range of 2 to 5 mm, the desired polishing allowance can be obtained. It was confirmed that an optical surface was obtained.
Separately from this, the same results were obtained by changing the toric surface shape of the lens to be polished, and the following results were obtained.
(1) When the sag. Value of the toric surface on the surface of the dome is 8 mm in the base direction and 10 mm in the cross direction, the shape of the concave surface and the surface of the dome is the same, and the surface to be polished is in the middle relationship. A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 5 mm.
(2) When the sag. Value of the toric surface on the dome surface is 10 mm in the base direction and 12 mm in the cross direction, the shape of the concave surface and the surface of the dome portion is the same, and the surface to be polished is in the middle and the surface to be polished A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 6 mm.
(3) When the sag. Value of the toric surface on the dome surface is 12 mm in the base direction and 16 mm in the cross direction, the shape of the concave surface and the dome surface is the same, and the surface to be polished is in the middle and the surface to be polished A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 1 to 6 mm.
(4) When the sag. Value of the toric surface on the dome surface is 14 mm in the base direction and 18 mm in the cross direction, the shape of the concave surface and the surface of the dome portion is the same, and the surface to be polished is in the middle relationship. A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 7 mm.
(5) When the sag. Value of the toric surface on the dome surface is 18 mm in the base direction and 20 mm in the cross direction, the shape of the concave surface and the surface of the dome portion is the same. A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 8 mm.
(6) When the sag. Value of the toric surface on the dome surface is 8 mm in the base direction and 12 mm in the cross direction, the concave surface and the dome surface have the same shape. A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 5 mm.
(7) When the sag. Value of the toric surface on the dome surface is 8 mm in the base direction and 18 mm in the cross direction, the concave surface and the dome surface have the same shape. A desired optical surface was obtained with an appropriate polishing allowance within the range where the maximum distance between the surface and the dome surface was 2 to 5 mm.
(8) When the outer diameter of the balloon member is 80 mm, the sag. Value of the toric surface on the dome surface is 10 mm in the base direction and 20 mm in the cross direction. A desired optical surface was obtained with an appropriate polishing allowance when the polishing surface was in the middle and the maximum distance between the surface to be polished and the surface of the dome portion was 2 to 6 mm.

  From the above results, the validity of the selection criteria for the polishing jig based on the separation distance was shown. According to the present invention, since the allowable range of the shape of the polishing jig with respect to the shape of the surface to be polished is widened, the number of items that can be handled by one polishing jig is increased compared to the conventional polishing method using an elastic polishing body. Can do. For example, it is possible to polish several thousand items by using several tens of polishing jigs.

  The present invention is useful in the field of manufacturing eyeglass lenses.

Claims (6)

A polishing jig having a convex portion made of an elastic material and a molded body molded into a lens shape having a concave surface are relatively disposed while supplying an abrasive between the convex portion of the polishing jig and the concave surface of the molded body. A method of manufacturing an optical lens comprising polishing the concave surface by moving,
A method for producing an optical lens, wherein a polishing jig satisfying the following (1) and (2) is selected and used as the polishing jig.
(1) When the convex part of the polishing jig is fitted to the concave surface of the molded object to be polished, it has a shape that comes into contact with the central part but separates at the peripheral part.
(2) When the polishing jig convex part is fitted in a state in which the concave surface of the molded object to be polished is opposed to the reference axis on the concave surface and the reference axis on the convex part, the separation distance at the peripheral part is set in advance. Or less than the allowable separation distance. The method of manufacturing an optical lens according to claim 1, wherein the reference axis on the concave surface is set in an axial direction that minimizes the average curvature on the concave surface. The method for manufacturing an optical lens according to claim 1, wherein a reference axis on the convex portion of the polishing jig is set in an axial direction in which an average curvature is minimum on the surface of the convex portion. The method of manufacturing an optical lens according to claim 1, wherein the relative movement is performed in a state where a reference axis on the concave surface and a reference axis on the convex portion are substantially parallel. The optical lens manufacturing method according to claim 1, wherein the reference axis on the concave surface is an astigmatic axis of the astigmatic lens. The method of manufacturing an optical lens according to claim 1, wherein the allowable separation distance is set in a range of 1 to 8 mm.

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