JP2013186296A - Spectacle lens and spectacle lens design method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectacle lens and a spectacle lens design method which are capable of reducing the number of kinds of block rings and suppressing manufacturing costs of the block rings.SOLUTION: The spectacle lens includes an element in which a surface on the object side is a toric surface. On said surface on the object side, the sag amounts are equal at at least three points having an equal distance from the geometrical center of the spectacle lens. Either of the three points is a point on either of two principal meridians of said surface on the object side.

Description

  The present invention relates to a spectacle lens and a spectacle lens design method.

  Conventionally, as a method of manufacturing a spectacle lens (hereinafter, also simply referred to as a lens), a lens called a semi-finished lens in which only an object-side surface (outer surface, convex surface) is optically finished is fixed to a lens fixture. A method of making a final lens shape by cutting and polishing the eyeball side surface (inner surface, concave surface) is known (for example, Patent Document 1). In this method, a block ring that supports the object-side surface of the semi-finished lens is placed between the semi-finished lens and the lens fixture, and an adhesive such as a low-melting-point alloy (alloy) is placed inside the block ring. By filling, the semi-finished lens is fixed to the lens fixture.

JP 2008-110476 A

  Progressive multifocal lens used for spectacle lenses suitable for correction of visual acuity such as presbyopia, a progressive multifocal lens (internal progressive lens) that has a progressive refracting surface added to the object-side surface on the eyeball-side surface. (Refractive power lens) is known. Also known is a progressive multifocal lens (double-sided progressive-power lens) called double-sided design that can be designed taking into account spectacle magnification, image shake and distortion by providing a toric surface or progressive surface on the object side surface. ing.

  The semi-finished lens used for manufacturing the progressive-power lens has a rotationally symmetrical (spherical) surface on the object side, so it is fixed using a flat block ring where the lens-supporting part is on the same plane. The block ring can be shared.

  However, when fixing a semi-finished lens whose shape on the object side is not rotationally symmetric, such as a semi-finished lens used in the manufacture of a double-sided progressive addition lens, the shape of the object-side surface of each semi-finished lens is It is necessary to prepare a large number of dedicated block rings, which increases the manufacturing cost and hinders efficiency in the manufacturing process.

  The present invention has been made in view of such problems. According to some aspects of the present invention, it is possible to provide a spectacle lens and a spectacle lens design method capable of reducing the type of block ring and suppressing the manufacturing cost of the block ring.

  (1) A spectacle lens according to an aspect of the present invention is a spectacle lens in which an object-side surface includes an element having a toric surface, and the object-side surface is separated from a geometric center of the spectacle lens. The sag amounts of at least three points having the same distance are the same, and any one of the at least three points is a point on one of the two main meridians of the surface on the object side.

  Here, the sag amount is orthogonal to the optical axis passing through the geometric center of the lens and from a plane in contact with the eyeball side surface (or object side surface) to any point on the object side surface of the lens. Distance.

  In the spectacle lens of this aspect, the sag amount of at least three points having the same distance from the geometric center is the same on the object-side surface including the toric surface element, and at least one of the three points is the main point. A point on the meridian. As a result, among the arbitrary points having the same distance from the geometric center, the sag amount between the point having the maximum or minimum curvature and the other two points having the same distance is the same, and therefore passes through the at least three points. A flat block ring having the same diameter as that of the circle (a block ring in which the annular portion supporting the lens is on the same plane) is used to stably support the spectacle lens of this aspect at least at three points. can do. Therefore, it is not necessary to prepare a dedicated block ring that matches the shape of the object side surface including the elements of the toric surface, so that the block ring can be shared and the production cost of the block ring can be reduced. An eyeglass lens can be provided. In this specification, “the distances are equal” includes a case where there is an error within an allowable range in addition to a case where the distances are completely equal. Specifically, when the spectacle lens is fixed to the block ring, if the at least three points can come into contact with the block ring, it can be within an error range. The phrase “the sag amount is the same” includes the case where there is an error within an allowable range in addition to the case where the sag amount is completely equal. Specifically, when the spectacle lens is fixed to the block ring, if the at least three points can come into contact with the block ring, it can be within an error range.

  (2) In this spectacle lens, the object side surface may further include a progressive surface element.

  According to this aspect, even when the object-side surface includes a toric surface element and a progressive surface element, the spectacle lens can be stably supported at at least three points. Accordingly, since it is not necessary to prepare a dedicated block ring, it is possible to provide a spectacle lens capable of reducing the manufacturing cost of the block ring by sharing the block ring.

  (3) A spectacle lens design method according to an aspect of the present invention is a spectacle lens design method for designing a spectacle lens in which an object side surface includes an element having a toric surface, and in the object side surface, The sag amount of at least three points having the same distance from the geometric center of the spectacle lens is the same, and any of the at least three points is on one of the two main meridians of the object side surface. The point.

  In the spectacle lens designed by the method of this aspect, the sag amount of at least three points having the same distance from the geometric center is the same on the object-side surface including the element of the toric surface, and at least three points. One is a point on the main meridian. As a result, among the arbitrary points having the same distance from the geometric center, the sag amount between the point having the maximum or minimum curvature and the other two points having the same distance is the same, and therefore passes through the at least three points. By using a flat block ring having the same diameter as the diameter of the circle, the spectacle lens of this aspect can be stably supported at the at least three points. Therefore, it is not necessary to prepare a dedicated block ring that matches the shape of the object side surface including the elements of the toric surface, so that the block ring can be shared and the production cost of the block ring can be reduced. A spectacle lens can be designed.

The figure for demonstrating the blocking method of a semi-finished lens. The figure for demonstrating the malfunction which generate | occur | produces when fixing the semi-finished lens whose object side surface is a toric surface using a flat type block ring. The figure for demonstrating the malfunction which generate | occur | produces when fixing the semi-finished lens whose object side surface is a toric surface using a flat type block ring. The figure which shows an example of a structure of the semifinished lens of this embodiment. The flowchart figure for demonstrating the design method of the semifinished lens of this embodiment. The figure which shows an example of the sag amount of the vertical direction and the horizontal direction in the surface at the side of a toric object. FIG. 7A is a diagram showing an example of the corrected lateral sag amount, and FIG. 7B is an enlarged view of a part of FIG. 7A.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Blocking Method First, a method (blocking method) for fixing a semi-finished lens to a lens fixture will be described with reference to FIG.

  A semi-finished lens 10 shown in FIG. 1 is a lens in which an object-side surface 10a (outer surface, convex surface) forms a spherical surface, and an eyeball-side surface 10b forms a flat surface. In the figure, the X axis, Y axis, and Z axis indicate the lateral direction, vertical direction, and thickness direction of the lens, respectively. The longitudinal direction of the lens is a direction (vertical direction) connecting the vertex on the top of the wearer and the vertex on the chin side when worn as spectacles. The lateral direction of the lens is a direction (horizontal direction) orthogonal to the longitudinal direction. The thickness direction coincides with the optical axis direction. Note that the origin of the X, Y, and Z axes is the geometric center. The eyeball side surface 10b may be a spherical surface. The same applies to the subsequent drawings.

  As shown in FIG. 1, a block ring 30 that supports (holds) the object-side surface 10 a of the semi-finished lens 10 is installed between the semi-finished lens 10 and the lens fixture 20. The semi-finished lens 10 is fixed to the lens fixture 20 by filling with an adhesive 40 (for example, a low melting point alloy or wax). The block ring 30 is a flat block ring in which an annular support portion 30a that supports a lens is on the same plane.

  As shown in FIG. 1, since the object-side surface 10a of the semifinished lens 10 is a spherical surface, the object-side surface 10a is in contact with the support portion 30a of the block ring 30 without a gap. Therefore, if the geometric center GC of the semi-finished lens 10 is arranged so as to coincide with the center of the block ring 30, the semi-finished lens 10 can be fixed horizontally. Further, for example, the semi-finished lens 10 can be arbitrarily tilted and fixed by using block rings 30 having different side walls (height in the Z-axis direction in FIG. 1) (inclined).

  2 and 3 are diagrams for explaining a problem that occurs when a semi-finished lens having a toric surface on the object side is fixed using a flat block ring.

  In the semifinished lens 20 shown in FIG. 2, the object-side surface 20a is a toric surface, and the curvature radius R2 of the main meridian MY in the Y-axis direction is larger than the curvature radius R1 of the main meridian MX in the X-axis direction. Yes. When such a semi-finished lens 20 is to be fixed using the flat block ring 30, only two points P1 and P2 on the principal meridian MY in the Y-axis direction having a large curvature radius on the object-side surface 20a are blocked. In contact with the ring 30, gaps CR <b> 1 and CR <b> 2 are formed between the main meridian MX in the X-axis direction having a small curvature radius and the block link 30. Therefore, the block ring 30 cannot stably support (hold) the semi-finished lens 20, and the semi-finished lens 20 is fixed at an unintended inclination.

  Further, as shown in FIG. 3, if the semifinished lens 20 supported by the two points P1 and P2 on the main meridian MY is tilted about the Y axis, one gap CR1 on the main meridian MX is eliminated and the main finish line 20 is eliminated. Although the point P3 on the meridian MX can be brought into contact with the block ring 30, the other gap CR2 on the main meridian MX is further increased, and the adhesive 40 leaks from the gap CR2. The main meridian (of the surface) is a meridian indicating the maximum curvature or the minimum curvature. The two principal meridians are two principal meridians that are orthogonal to each other on the spherical surface, and the main meridian representing the maximum curvature and the main meridian representing the minimum curvature on the aspheric surface. Therefore, although the directions of the two main meridians coincide with the X-axis direction and the Y-axis direction in this specification, they do not necessarily coincide with the X-axis direction and the Y-axis direction.

  In the semi-finished lens of the present embodiment (corresponding to the eyeglass lens of the present invention), the sag amount of at least three points having the same distance from the geometric center (optical center, fitting point) of the lens is the same on the object side surface. As a result, the above problems are improved.

2. Configuration FIG. 4 is a diagram showing an example of the configuration of the semi-finished lens of the present embodiment. Here, a semi-finished lens used for manufacturing a double-sided progressive addition lens will be described by taking as an example a lens including a toric surface element on the object side surface. By including a toric surface element on the object-side surface, image shake and distortion can be reduced.

  The semi-finished lens 50 of the present embodiment shown in FIG. 4 is a lens in which the object-side surface 50a includes a toric surface element, and the eyeball-side surface 50b forms a flat surface. That is, the curvature radius R2 of the main meridian MY in the Y-axis direction of the object-side surface 50a is larger than the curvature radius R1 of the main meridian MX in the X-axis direction. That is, the surface refractive power in the horizontal direction (X-axis direction) of the object-side surface 50a is larger than the surface refractive power in the vertical direction (Y-axis direction).

  Here, when viewed in the lateral direction (X-axis direction) of the object-side surface 50a, the semi-finished lens 50 of the present embodiment has a predetermined width W with the main meridian MY (main meridian) in the Y-axis direction as the center. Only the region is a toric surface region having a constant radius of curvature (constant surface power), and the left and right regions of the region are aspherical shapes whose curvature radius (surface power) changes continuously. It is an area.

  The aspherical region of the object-side surface 50a has a sag amount of two points P3 and P4 on the main meridian MX that is separated from the geometric center GC by a predetermined distance L from the geometric center GC. This coincides with the sag amount of the points P1 and P2 on the main meridian MY separated by L. Therefore, as shown in FIG. 4, the object-side surface 50a is formed at two points P1 and P2 on the main meridian MY in the Y-axis direction and two points P3 and P4 on the main meridian MX in the X-axis direction. It comes into contact with the support 30a of the block ring 30 having a radius equal to the distance L. When the sag amount is defined as a distance from a plane perpendicular to the optical axis passing through the geometric center GC and in contact with the eyeball-side surface 50b to an arbitrary point on the object-side surface 50a, at least three points (here, The sag amount of the points P1, P2, P3, and P4) is greater than or equal to the sag amount of other points on the concentric circles having the same distance (the distance L) from the geometric center GC of the object-side surface 50a.

  As described above, in the semi-finished lens 50 according to the present embodiment, the sag amounts of the four points P1 to P4 that are separated from the geometric center GC by the predetermined distance L coincide on the object-side surface 50a including the toric surface element. Therefore, the semi-finished lens 50 can be stably supported at the four points P1 to P4 using the flat block ring 30 having a radius equal to the distance L. Therefore, even when a semi-finished lens including a toric surface element is fixed to the object side surface, it is not necessary to prepare a dedicated block ring that matches the shape of the object side surface. It is possible to reduce the manufacturing cost of the block ring by making it common. Of the four points P1 to P4, it is only necessary that the sag amounts of any three points match. The point P3 and the point P4 may be points that are separated from the geometric center GC by the distance L, and may not be points on the main meridian MX in the X-axis direction.

  Further, in the semi-finished lens 50 according to the present embodiment, the torsional surface shape is maintained by maintaining the shape of the toric surface in a region having a predetermined width W including the main meridian MY (main meridian), and the image shake, which is the purpose of the toric surface shape. In addition, the influence on the distortion reduction effect can be minimized. The region for maintaining the shape of the toric surface may be a region including the geometric center GC, and for example, a circular region centered on the geometric center GC may be used as the toric surface region.

  The object-side surface 50a of the semi-finished lens 50 may include a progressive surface element. A progressive surface (progressive refractive surface, progressive portion) is such that the refractive power continuously changes between a distance portion that is a visual field portion for far vision and a near portion that is a visual field portion for near vision. It is an area connected to. The distance portion is provided above the lens (on the top of the head when worn), and the near portion is provided below the lens (on the chin side when worn). When a progressive surface is included in the object-side surface 50a, the curvature on the main meridian MY is not constant, and the sag amounts at the two points P1 and P2 on the main meridian MY in the Y-axis direction are not the same. In this case, the sag amounts of the two points P3 and P4 on the main meridian MX in the X-axis direction are made to coincide with one of the points P1 and P2, and three points (points P1, P3, P4) Alternatively, the sag amounts of P2, P3, and P4) may be matched. The progressive surface elements may be distributed between the object-side surface 50a and the eyeball-side surface 50b. The progressive surface element may be a reverse progressive element (an element in which the addition decreases between the distance portion and the near portion).

3. Design Method Next, the design method of the semi-finished lens of the present embodiment will be described with reference to the flowchart of FIG.

  Here, as an example, the refractive index of the lens material is 1.67, the surface refractive power in the longitudinal direction (Y-axis direction) of the object-side surface 50a is 5.00 D (diopter), and the lateral direction (X-axis direction). Assuming a semi-finished lens having a surface refractive power of 6.00D, a case where a flat block ring having a radius of 30 mm is used as the block ring will be described.

  First, the object-side surface 50a is designed in the shape of a toric surface, and the sag amount of each point on the object-side surface 50a is calculated (step S10). The sag amount Z of each point on the toric surface can be obtained by the following equation (1).

  Here, C is the curvature (unit: 1 / mm), and R is the distance from the geometric center (unit: mm).

  FIG. 6 shows the sag amount of each point in the vertical direction from the geometric center (each point on the principal meridian MY in the Y-axis direction) obtained from the object-side surface 50a of the semifinished lens under the above conditions, and the geometric center. It is a figure which shows the calculation result of the sag amount of each point of horizontal direction (each point of MX on the principal meridian of the X-axis direction). Here, the sag amount is a distance from a plane perpendicular to the optical axis passing through the geometric center and in contact with the object-side surface 50a to each point on the object-side surface 50a. The vertical sag amount in FIG. 6 indicates the shape of the partial cross section in the lens vertical direction, and the horizontal sag amount indicates the shape of the partial cross section in the lens horizontal direction. As shown in FIG. 6, at a position 30 mm from the geometric center (a position corresponding to a contact position with a block ring having a radius of 30 mm), the sag amount is 3.4 mm in the vertical direction and 4.2 mm in the horizontal direction. The difference Δ is 0.8 mm. That is, when the semi-finished lens of the above condition is to be supported by a flat block ring having a radius of 30 mm, the longitudinal direction of the lens comes into contact with the block ring first, and is located 30 mm to the left and right from the geometric center in the lateral direction of the lens. Since gaps CR1 and CR2 of 0.8 mm are generated, it is necessary to correct the sag amount in the horizontal direction or the vertical direction. Here, a case where the sag amount in the horizontal direction is corrected will be described.

Next, prior to the correction of the sag amount, a sag amount serving as a target (target value) is determined (step S12 in FIG. 5), and the aspheric coefficient used for the correction of the sag amount based on the determined sag amount of the target. a ₃ and a ₄ are determined (step S14). The sag amount is corrected using the following equation (2).

Here, R ₀ is the distance (unit: mm) from the geometric center which is the upper limit of the range in which the shape of the toric surface is maintained, and is a half value (R ₀ = W) of the predetermined width W shown in FIG. / 2). Here, the design is performed with R ₀ = 5 mm. Further, a ₃ and a ₄ are aspheric coefficients.

As shown in FIG. 6, in the semi-finished lens of the above condition, the vertical sag amount is smaller than the horizontal sag amount at the distance R = 30 mm from the geometric center, and therefore the vertical direction at the distance R = 30 mm. The sag amount “3.4 mm” is determined as the sag amount of the target. Then, the aspherical coefficients a ₃ and a ₄ are determined so that the lateral sag amount at the distance R = 30 mm becomes the target sag amount Z = 3.4 mm, and the lateral sag amount is corrected. That is, in Equation (2), Z = 3.4 mm, C = the lateral curvature of the lens, R = 30 mm, and R ₀ = 5 mm are substituted to calculate the aspheric coefficients a ₃ and a ₄ . In this case, since there are two variables a ₃ and a ₄ , the other aspheric coefficient may be calculated with one being a constant. Further, in the expression (2), one aspheric coefficient term of a ₃ and a ₄ may be excluded. Further, although the third-order and fourth-order aspheric coefficients are used in Equation (2), any order of aspheric coefficients can be used.

Next, the sag amount is corrected based on the aspheric coefficient determined in step S14 (step S16 in FIG. 5). That is, the amount of sag at each point in the horizontal direction (X-axis direction) is recalculated according to Expression (2) in which the values of the calculated aspheric coefficients a ₃ and a ₄ are substituted. However, in the range of 0 ≦ R ≦ R ₀ , the shape of the toric surface is maintained, so that the calculation result by the formula (1) is maintained for each point in this range, and the lateral direction of the range of R> R ₀ is maintained. Only for each point, the sag amount is recalculated and corrected by the equation (2) (the lateral aspheric amount in the range of R> R ₀ is changed).

  FIG. 7A shows the sag amount at each point in the horizontal direction after correction. As shown in FIG. 7A, the corrected sag amount in the horizontal direction matches the sag amount in the vertical direction at a distance R = 30 mm, which is a position corresponding to the contact position with the block ring. That is, the shape in the horizontal direction where the curvature is constant has been changed to an aspherical shape so as to coincide with the sag amount in the vertical direction at the distance R = 30 mm by the correction using the aspheric coefficient.

FIG. 7B is an enlarged view of the range of 0 ≦ R ≦ 10 in FIG. As shown in FIG. 7B, in the range of 0 ≦ R ≦ R ₀ (R ₀ = 5 mm), the sag amount in the horizontal direction is the same before and after the correction. The shape of the toric surface with a constant curvature is maintained.

As described above, the sag amount in the vertical direction and the sag amount in the horizontal direction within the range of 0 ≦ R ≦ R ₀ are calculated by the equation (1), and the vertical direction sag amount corresponding to the contact position with the block ring is calculated. The sag amount is determined as the sag amount of the target, an aspheric coefficient is obtained based on the determined sag amount of the target, and the lateral sag in the range of R> R ₀ is calculated based on the obtained aspheric coefficient and Equation (2). Calculate the quantity.

The lateral sag amount at the position corresponding to the contact position with the block ring is determined as the sag amount of the target, and the vertical surface in the range of R> R ₀ is determined using the aspheric coefficient obtained based on the sag amount of the target. The aspherical amount of the direction may be changed.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10, 20, 50 Semi-finished lens, 10a, 20a, 50a Object side surface, 10b, 20b, 50b Eye side surface, 20 Lens fixture, 30 Block ring, 30a Lens support, 40 Adhesive, CR1, CR2 Gap, GC geometric center, L predetermined distance, MY, MX principal meridian, P1, P2, P3, P4 points, R1, R2 radius of curvature, W predetermined width

Claims (3)

A lens for spectacles in which the object side surface includes an element of a toric surface,
On the object side surface, the sag amounts of at least three points having the same distance from the geometric center of the spectacle lens are the same,
The eyeglass lens, wherein any one of the at least three points is a point on one of the two main meridians of the object side surface. In claim 1,
The spectacle lens, wherein the object-side surface further includes a progressive surface element. A spectacle lens design method for designing a spectacle lens in which an object side surface includes an element of a toric surface,
On the object side surface, the sag amount of at least three points having the same distance from the geometric center of the spectacle lens is the same,
A spectacle lens designing method, wherein any one of the at least three points is a point on one of two principal meridians of the object side surface.

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