Spectacle lens and method for manufacturing a spectacle lens

Abstract

An eyeglass lens having an inner prism that bends light toward the wearer's nose, at least in the far-side region of the additional prism curve, which is expressed as a function of coordinates in the vertical direction of the eyeglass lens, the eyeglass lens having a reverse prism gradient with a different sign than the additional prism gradient on the asymptote, and the absolute value of the reverse prism gradient being greater than 0.014 times the absolute value of the additional prism gradient on the asymptote.

Description

Technical Field

[0001] This invention relates to an eyeglass lens and a method for manufacturing an eyeglass lens. Background Technology

[0002] It is known that adding an internal prism in an amount corresponding to the diopter conversion value of the viewing distance causes light to bend toward the wearer's nose, thereby supporting the reduction of convergence due to aging and reducing fatigue. Furthermore, it is known that when an internal prism is added according to the viewing distance, astigmatism occurs due to the distortion of the lens surface; therefore, for example, in Patent Document 1, to reduce aberrations, a smooth, monotonically increasing curve is proposed instead of the additional prism curve.

[0003] [Existing Technical Documents]

[0004] [Patent Literature]

[0005] Patent document 1: Japanese Patent Application Publication No. 2018-97283. Summary of the Invention

[0006] [The problem this invention aims to solve]

[0007] Embodiments of the present invention aim to provide a technique for reducing third-order aberrations in additional eyeglass lenses by using an internal prism that bends light toward the wearer's nose, depending on the viewing distance.

[0008] [Solution to the problem]

[0009] The first aspect of the present invention is:

[0010] An eyeglass lens, wherein an internal prism is added to the lens to bend light toward the wearer's nose.

[0011] At least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, the spectacle lens has a reverse prism gradient with a different sign than the additional prism gradient on the asymptote.

[0012] The absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote.

[0013] The second aspect of the invention is:

[0014] According to the spectacle lens of the first aspect, the absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote, both on the principal meridian of the spectacle lens and at the umbilicus point shifted towards the wearer's nose by the inner prism.

[0015] The third aspect of the present invention is:

[0016] According to the first or second aspect, the absolute value of the reverse prism gradient is less than 0.00625Δ / mm.

[0017] The fourth aspect of the present invention is:

[0018] According to the spectacle lens of the third aspect, the absolute value of the reverse prism gradient is less than 0.00625Δ / mm on both the principal meridian of the spectacle lens and at the umbilicus point shifted towards the wearer's nose by the inner prism.

[0019] The fifth aspect of the present invention is:

[0020] The spectacle lens according to any one of the first to fourth aspects, wherein the amount of added inner prism varies depending on the viewing distance.

[0021] The sixth aspect of the present invention is:

[0022] The spectacle lens according to any one of the first to fifth aspects, wherein the difference between the maximum and minimum values ​​of the added internal prism amount is 0.25Δ or more.

[0023] The seventh aspect of the present invention is:

[0024] A method for manufacturing an eyeglass lens, wherein the eyeglass lens is equipped with an internal prism that bends light toward the wearer's nose, the manufacturing method comprising:

[0025] At least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, the prism design step involves designing the spectacle lens to have a prism gradient with a reverse prism gradient of a different sign than the additional prism gradient on the asymptotic band.

[0026] In the prism design step, the absolute value of the reverse prism gradient is designed to be greater than 0.014 times the absolute value of the additional prism gradient on the asymptote.

[0027] [Invention Effects]

[0028] According to an embodiment of the present invention, an internal prism that bends light toward the wearer's nose can reduce third-order aberrations in additional spectacle lenses depending on the viewing distance. Attached Figure Description

[0029] Figure 1 (a) is an example of a power distribution map and aberration distribution map without an internal prism. Figure 1 (b) is an example of a power distribution map and aberration distribution map with an internal prism.

[0030] Figure 2(a) is a graph showing an example of an additional prism curve expressed as a function of the coordinates in the vertical direction of the spectacle lens, and Figure 2 (b) is a graph showing an example of the variation in the sag Z around the principal meridian.

[0031] Figure 3 (a) is a graph showing an example of an additional prism curve. Figure 3 (b) is a graph showing an example of the gradient of the additional prism curve (the first derivative of the additional prism curve). Figure 3 (c) is a graph showing an example of the curvature of the additional prism curve (the second derivative of the additional prism curve).

[0032] Figure 4 (a) is a graph showing an example of the additional prism curve when the value of q in equation (1) is varied. Figure 4 (b) is a graph showing the relationship between the value of q, the minimum / maximum value of the gradient of the additional prism curve, and the maximum curvature of the additional prism curve.

[0033] Figure 5 (a) to Figure 5 (c) is a graph showing the additional prism curves of samples 2 to 4 according to the embodiment.

[0034] Figure 6 (a) to Figure 6 (d) is a graph showing the degree distribution, astigmatism distribution and third-order aberration distribution of samples 1 to 4 according to the embodiment.

[0035] Figure 7 (a) to Figure 7 (c) is a graph showing the internal prism, focal length, astigmatism and third-order aberration at the location of the line of sight of samples 2 to 4 according to the embodiment. Detailed Implementation

[0036] <Knowledge Acquired by the Inventor>

[0037] First, the inventor's discovery will be explained.

[0038] In this specification, the upper side is indicated as positive and the lower side as negative in the vertical direction of the spectacle lens, and the wearer's ear side is indicated as positive and the wearer's nose side as negative in the horizontal direction of the spectacle lens. Furthermore, the origin point is, for example, the center of the lens (at least one of the geometric center, optical center, and centering center).

[0039] The method described in Patent Document 1, etc., only optimizes astigmatism along the principal meridian caused by the distortion of the lens surface. However, after adding an inner prism, the line of sight does not initially pass through the original principal meridian, so it is considered to be of little significance. Furthermore, in this specification, the principal meridian refers to the line formed by the convergence of the portion of the line of sight passing through the lens when the wearer wears the spectacle lenses and moves their line of sight from top to bottom. This principal meridian is the basis for designing spectacle lenses.

[0040] Figure 1 (a) is an example of a power distribution diagram and an astigmatism (AS) distribution diagram without an internal prism. Figure 1 (b) is an example of a power distribution diagram and astigmatism distribution diagram with an internal prism. Figure 1 (a) and Figure 1 In (b), the left side of the diagram is the nasal side. From Figure 1 (a) and Figure 1 (b) It can be seen that due to the endoscopic prism, the power is asymmetrical, with a lower power in the nasal distal region and a higher power in the nasal near region. In addition, it can be seen that the umbilicus (the area where astigmatism is relatively small relative to the prescription error in the middle and near regions of progressive power lenses) has shifted towards the nasal side.

[0041] The inventors discovered through research that as the umbilicus shifts nasally due to the internal prism, the line of sight also shifts nasally. More specifically, they found that the line of sight tends to pass through the middle position of the original principal meridian and the shifted umbilicus. Based on this, the inventors discovered a new problem with spectacle lenses containing internal prisms. Specifically, the problem is that as the line of sight shifts nasally, the power in the distance-use region is insufficient (the power in the near-use region is excessive). Furthermore, the following problem exists: as the power at the line of sight changes, the amount of internal prism added in the distance-use region becomes excessive (and insufficient in the near-use region).

[0042] Figure 2 (a) is a graph showing an example of an additional prism curve expressed as a function of the coordinates in the vertical direction of the spectacle lens, and Figure 2 (b) is a graph showing an example of the variation in the sag Z around the principal meridian. Figure 2 (a) illustrates the case where the additional prism curve is set to a monotonically increasing curve (monotonically increasing downwards, the same below). Figure 2 In (b), the solid line represents the droop Z at a position 1 mm (X = 1 mm) shifted from the principal meridian toward the ear, and the dashed line represents the droop Z at a position 1 mm (X = -1 mm) shifted from the principal meridian toward the nose. Furthermore, Figure 2 (a) and Figure 2 In (b), the horizontal axis (Y) represents the coordinates in the vertical direction of the eyeglass lens.

[0043] exist Figure 2 In (b), in region Z1, oblique astigmatism occurs because the gradient (dZ / dY) of the droop Z varies with the horizontal coordinate (X). This increases aberrations along the principal meridian and shifts the umbilicus towards the nasal side. On the other hand, in region Z2, third-order aberrations occur because the curvature (d2Z / dY2) of the droop Z varies with the horizontal coordinate (X). Furthermore, the degrees differ between the auricular and nasal sides, particularly in the distal nasal region where the degrees are smaller.

[0044] The inventors conducted in-depth research, paying particular attention to the aforementioned third-order aberrations. As a result, they discovered that the problem could be solved by designing spectacle lenses in the following manner: at least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, the spectacle lens is designed to have a reverse prism gradient with a different sign than the additional prism gradient on the asymptote.

[0045] Figure 3 (a) is a graph showing an example of an additional prism curve. Figure 3 (b) is a graph showing an example of the gradient of the additional prism curve (the first derivative of the additional prism curve). Figure 3 (c) is a graph showing an example of the curvature of the additional prism curve (the second derivative of the additional prism curve). Figure 3 (a) to Figure 3 In (c), the dashed line represents the case where the additional prism curve is set to a monotonically increasing curve, and the solid line represents the case where the additional prism curve has a reverse prism gradient. Furthermore... Figure 3 (a) to Figure 3 In (c), the horizontal axis represents the coordinates in the vertical direction of the eyeglass lens.

[0046] from Figure 3 (c) It can be seen that when the additional prism curve has a reverse prism gradient, the absolute value of the curvature is smaller than when the additional prism curve is set to a monotonically increasing curve. Therefore, the third-order aberration caused by the curvature change can be reduced. By reducing the third-order aberration, the diopter fluctuation caused by the shift in the line of sight position can be reduced. Furthermore, when the additional prism curve has a reverse prism gradient, the problem of excessive internal prism amount in the far-side region can be solved by adding a negative prism in the far-side region.

[0047] [Detailed Description of Embodiments of the Invention]

[0048] Embodiments of the present invention will now be described with reference to the accompanying drawings. Furthermore, the present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0049] Furthermore, the term "horizontal direction" in this specification refers to the 0 or 180-degree direction defined in the astigmatic axis and prism base direction, and describes an example where the direction is consistent with the horizontal reference line connecting the two alignment reference marks (so-called hidden marks) used for framing in the frame. In addition, the horizontal reference line in this embodiment is a line extending horizontally between the upper and lower vertices of the spectacle lens (a circular lens before framing). Furthermore, in this embodiment, an example will be described where the hidden marks are configured such that the principal meridian passes through the center of the horizontal reference line connecting the two hidden marks.

[0050] Furthermore, in this embodiment, the principal meridian in the progressive power lens can be a line connecting the distance power measurement point and the near power measurement point.

[0051] <First Embodiment of the Invention> (1) Structure of the Spectacle Lens

[0052] First, the structure of the spectacle lens in this embodiment will be described. The spectacle lens in this embodiment is, for example, a progressive lens in which a portion or all of a single lens contains a continuously varying portion (progressive zone) of refractive power. The spectacle lens has an optical surface formed on the side of an object based on a predetermined design. As spectacle lenses, this includes not only so-called finished lenses with predetermined optical surfaces on the side of the eyeball, but also, for example, semi-finished lenses that can be obtained by further polishing the side of the eyeball according to a prescription. Furthermore, progressive lenses generally include lenses called diopter lenses, intermediate / near lenses, near-near lenses, and lenses called accommodation support lenses, etc. The inner prism, which will be described later, can be added to the object side or the eyeball side, and there is no particular limitation on whether it is added to the progressive surface side.

[0053] In this embodiment of the spectacle lens, an inner prism is added to bend light toward the wearer's nose, depending on the viewing distance. That is, in this embodiment, the amount of inner prism added varies depending on the viewing distance; for example, the amount of inner prism in the near-viewing area is greater than that in the far-viewing area. The inner prism is useful, for example, when a wearer with weak converging power is viewing nearby objects. In this embodiment, for example, the difference between the maximum and minimum amount of added inner prism is preferably 0.25Δ (prism diopter) or more, more preferably 1Δ or more. In this case, since the change in diopter caused by the shift in the viewing position more easily affects the appearance of the spectacle lens, the effect of the present invention is more significant. Furthermore, there is no particular limitation on the upper limit of the difference between the maximum and minimum amount of added inner prism, for example, it is 6Δ or less (or 2Δ or less).

[0054] The spectacle lens of this embodiment has a reverse prism gradient with a different sign from the additional prism gradient on the asymptote, at least in the far-use region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens. Furthermore, in this specification, the far-use region of the additional prism curve refers to the region above the position (or asymptote) where the gradient of the additional prism curve is maximum, and the near-use region refers to the region below the position (or asymptote) where the gradient of the additional prism curve is maximum. Additionally, the additional prism gradient on the asymptote can be the maximum value of the gradient of the additional prism curve.

[0055] However, compared to the case where the additional prism curve is a monotonically increasing curve, simply applying a reverse prism gradient to the far-side region of the additional prism curve may not reduce the absolute value of the curvature of the additional prism curve. To reduce the absolute value of the curvature of the additional prism curve and reduce third-order aberrations, the amount of the applied reverse prism gradient needs to be appropriately controlled. Specifically, the spectacle lens of this embodiment preferably satisfies the following conditions A, B, and C.

[0056] (Condition A)

[0057] Figure 3 The additional prism curve shown in (a) can be represented by the following sigmoid function (Equation (1)). Below, taking the case where the additional prism curve is represented by a sigmoid function as an example, we describe the minimum amount of reverse prism gradient required to reduce third-order aberrations.

[0058] [Mathematical Expression 1]

[0059]

[0060] Figure 4 (a) is a graph showing an example of the additional prism curve when the value of q in equation (1) is varied. Figure 4 As shown in (a), it can be seen that when q = 0, the additional prism curve is a monotonically increasing curve, but when q = 0.7 and q = 1.1, the additional prism curve is given a reverse prism gradient. Figure 4 (b) is a graph showing the relationship between the value of q, the minimum / maximum value of the gradient of the additional prism curve, and the maximum curvature of the additional prism curve. Figure 4 In (b), the solid line represents the minimum / maximum value of the gradient of the additional prism curve, and the dashed line represents the maximum curvature of the additional prism curve (the relative value when q=0 is set to 1).

[0061] The fact that the minimum / maximum values ​​of the gradient of the additional prism curve are positive means that the minimum and maximum values ​​of the gradient of the additional prism curve have the same sign. That is, Figure 4(b) shows region Z3, which is the region where the additional prism curve does not have a reverse prism gradient. On the other hand, regions Z4 and Z5, where the minimum / maximum values ​​of the gradient of the additional prism curve are negative, are regions where the additional prism curve has a reverse prism gradient. Furthermore, when the additional prism curve has a reverse prism gradient, the minimum value of the gradient of the additional prism curve can be regarded as the reverse prism gradient, so the minimum / maximum value of the gradient of the additional prism curve can be expressed as the reverse prism gradient / the additional prism gradient on the asymptote.

[0062] like Figure 4 As shown in (b), in region Z4, the maximum curvature of the additional prism curve is greater than when q = 0. That is, region Z4 is a region in which, although the additional prism curve has a reverse prism gradient, the absolute value of the curvature of the additional prism curve does not become smaller than when the additional prism curve is a monotonically increasing curve. For example, Figure 4 (a) shows that the additional prism curve with q = 0.7 has a larger absolute value of curvature than the additional prism curve with q = 0 (the monotonically increasing curve).

[0063] On the one hand, in region Z5, the maximum curvature of the additional prism curve is smaller than when q = 0. That is, when q > 0.9 (region Z5), the absolute value of the curvature of the additional prism curve is smaller than the absolute value of the curvature when the additional prism curve is a monotonically increasing curve. For example, Figure 4 (a) shows that the additional prism curve with q = 1.1 has a smaller absolute value of curvature than the additional prism curve with q = 0 (the monotonically increasing curve).

[0064] In region Z5, the value of q corresponds one-to-one with the minimum / maximum value of the gradient of the additional prism curve. Therefore, when q > 0.9, the minimum / maximum value of the gradient of the additional prism curve can also be expressed as less than -0.014. The minimum / maximum value of the gradient of the additional prism curve can also be expressed as the reverse prism gradient / the additional prism gradient on the asymptote. Therefore, in region Z5, the absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote. Thus, when the absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote, the absolute value of the curvature of the additional prism curve is smaller compared to the case where the additional prism curve is a monotonically increasing curve, thereby reducing third-order aberrations.

[0065] (Condition B)

[0066] Condition A already describes how third-order aberrations can be reduced when the absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote. On the other hand, if the absolute value of the reverse prism gradient is too large, oblique astigmatism may occur, which could adversely affect the visibility of the spectacle lens. The preferred range of the reverse prism gradient will be described below to prevent oblique astigmatism caused by the reverse prism gradient from adversely affecting the visibility of the spectacle lens.

[0067] Astigmatism is typically measured in units of 0.25D. Therefore, if the astigmatism is less than half of this (0.125D), its impact on the visibility of spectacle lenses can be considered negligible. From the relationship between the amount of astigmatism generated by the reverse prism gradient (D) = 2 × 10 × reverse prism gradient (Δ / mm), it can be seen that if the absolute value of the reverse prism gradient is less than 0.00625Δ / mm, the amount of astigmatism generated by the reverse prism gradient can be suppressed to less than 0.125D. Therefore, to prevent oblique astigmatism caused by the reverse prism gradient from adversely affecting the visibility of spectacle lenses, it is preferable that the absolute value of the reverse prism gradient is less than 0.00625Δ / mm.

[0068] (Condition C)

[0069] Regarding the conditions for the reverse prism gradient described in conditions A and B, it is preferable that both the conditions be satisfied on the principal meridian of the spectacle lens and on the line "passing through the point farthest from the principal meridian and parallel to the principal meridian among the umbilicus points shifted towards the wearer's nose due to the internal prism." Furthermore, to avoid complications, in this specification, "passing through the point farthest from the principal meridian and parallel to the principal meridian among the umbilicus points shifted towards the wearer's nose due to the internal prism" is also referred to as "on the umbilicus point shifted towards the wearer's nose due to the internal prism" or "on the shifted umbilicus point." That is, on the principal meridian of the spectacle lens and on the umbilicus point shifted towards the wearer's nose due to the internal prism, the absolute value of the reverse prism gradient is preferably greater than 0.014 times the absolute value of the additional prism gradient on the asymptote. Furthermore, on the principal meridian of the spectacle lens and at the umbilicus, which shifts towards the wearer's nose due to the internal prism, the absolute value of the reverse prism gradient is preferably less than 0.00625Δ / mm. In this embodiment, the umbilicus is defined as the region enclosed by the contour line with the minimum astigmatism in the astigmatism distribution map. However, this is not applicable to regions where astigmatism is locally reduced due to manufacturing errors, etc.

[0070] As described above, when the umbilicus shifts towards the nose, the line of sight tends to pass through the middle position between the original principal meridian and the shifted umbilicus. Therefore, satisfying condition A (or condition B) on the principal meridian of the spectacle lens and on the umbilicus shifted towards the wearer's nose due to the prism means that even if the line of sight shifts to the nose, the effect of satisfying condition A (or condition B) is maintained.

[0071] Next, the umbilicus shift amount is described, which represents the degree to which the umbilicus shifts from its original principal meridian when it is displaced nasally due to the internal prism. The umbilicus shift amount is calculated as the astigmatism generation (D) caused by the internal prism / the astigmatism gradient in the horizontal direction of the spectacle lens (D / mm). Furthermore, based on the relationships “astigmatism generation (D) caused by the internal prism = 2 × 10 × additional prism gradient on the asymptote (Δ / mm)” and “astigmatism gradient in the horizontal direction of the spectacle lens (D / mm) = 2 × additional power gradient (D / mm)”, the umbilicus shift amount (mm) can be calculated using the relationship “umbilicus shift amount (mm) = 10 × additional prism gradient on the asymptote (Δ / mm) / additional power gradient (D / mm)”. By shifting the umbilicus shift amount (to its maximum value) parallel to the principal meridian and nasal side, the “umbilicus shifted nasally due to the internal prism” can be specified.

[0072] In the near-use region of the additional prism curve, there may be a reverse prism gradient, or there may be no reverse prism gradient. When a reverse prism gradient exists in the near-use region, it is preferable that the reverse prism gradient in the near-use region also satisfies conditions A, B, and C above. Furthermore, as... Figure 3 As shown by the solid line in (a), the reverse prism gradients of the far-side region and the near-side region can be symmetrical.

[0073] (2) Manufacturing method of spectacle lenses

[0074] The manufacturing method of the spectacle lens according to this embodiment will now be described. Furthermore, in the following description, for any content not described in this specification, known techniques may be employed.

[0075] (Preparation process)

[0076] In the preparation process, preparations are made for subsequent design processes. For example, when designing eyeglass lenses, the first step is to gather necessary information. This information can be broadly categorized into project-specific information (i.e., lens project-specific data) and wearer-specific information (i.e., wearer-specific data). Project-specific information includes details about the lens material's refractive index (n), progressive surface design parameters expressed in terms of progressive band length, etc. Wearer-specific information includes information about distance prescriptions (spherical power S, astigmatism power C, astigmatic axis AX, prism power P, prism base direction PAX, etc.), additional power (ADD), layout data (distance PD, near PD, eye point position, etc.), frame shape, and parameters representing the positional relationship between the frame and the eye (forward tilt angle, torsion angle, distance between vertices, etc.).

[0077] (Design process)

[0078] In the design process, the spectacle lens is designed based on the information obtained in the preparation process. The design process includes a prism design process that designs the shape of the inner prism. In the prism design process, the shape of the inner prism is designed such that, at least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, it has a reverse prism gradient with a different sign than the additional prism gradient on the asymptote.

[0079] In the prism design process, it is preferable to design the shape of the inner prism to satisfy conditions A, B, and C above. That is, in the prism design process, it is preferable to design the absolute value of the reverse prism gradient to be greater than 0.014 times the absolute value of the additional prism gradient on the asymptote. Furthermore, on the principal meridian of the spectacle lens and at the umbilicus that shifts towards the wearer's nose due to the inner prism, it is preferable to design the absolute value of the reverse prism gradient to be greater than 0.014 times the absolute value of the additional prism gradient on the asymptote. Furthermore, it is preferable to design the absolute value of the reverse prism gradient to be less than 0.00625Δ / mm. Furthermore, on the principal meridian of the spectacle lens and at the umbilicus that shifts towards the wearer's nose due to the inner prism, it is preferable to design the absolute value of the reverse prism gradient to be less than 0.00625Δ / mm. By designing the shape of the inner prism in this way, various effects described in the structure of the spectacle lens (1) can be obtained. In addition, the present invention can be applied not only to the manufacturing method of spectacle lenses but also to the design method of spectacle lenses.

[0080] (Manufacturing process)

[0081] In the manufacturing process, eyeglass lenses are manufactured based on the design results from the design process. Regarding the specific manufacturing method, well-known methods can be used. For example, the design data obtained in the design process can be input into a processing machine to process the lens blank, thereby manufacturing eyeglass lenses.

[0082] In addition, additional processes beyond those mentioned above (e.g., cleaning process, coating process, etc.) may be added as needed.

[0083] Through the above process, spectacle lenses with reduced third-order aberrations can be manufactured.

[0084] <Other embodiments of the present invention>

[0085] The embodiments of the present invention have been described above in detail, but the present invention is not limited to the above embodiments and can be modified in various ways without departing from its spirit.

[0086] For example, taking into account the aforementioned umbilical displacement, the embedding amount and wearing point in the progressive refractive power lens can also be adjusted.

[0087] [Example]

[0088] Next, embodiments according to the present invention will be described. These embodiments are examples of the present invention, and the present invention is not limited to these embodiments.

[0089] (1) Preparation of spectacle lenses

[0090] First, as shown below, samples 1 to 4 were prepared as eyeglass lenses.

[0091] Sample 1 was designed as a progressive lens without an internal prism. The additional power gradient of the progressive band was set to -0.141D / mm. Furthermore, the additional power gradient of the progressive band was set the same for Samples 2 through 4 below.

[0092] Sample 2 is configured as a progressive refractive power lens with an added inner prism proportional to the viewing distance. The additional prism curve of Sample 2 is as follows: Figure 5 As shown in (a). In Figure 5 In (a), the solid line represents the additional prism curve on the principal meridian, and the dashed line represents the additional prism curve at the shifted umbilicus. On the principal meridian, the additional prism gradient on the asymptote is set to -0.086Δ / mm, and the maximum curvature is set to 0.0112Δ / mm. 2 Furthermore, it is set to have no reverse prism gradient. At the displaced umbilicus (umbilicus displacement = 6.1 mm), the additional prism gradient on the asymptote is -0.084Δ / mm, the maximum curvature is set to 0.0109Δ / mm², and it is set to have no reverse prism gradient.

[0093] Sample 3 is designed as a progressive refractive power lens with an added inner prism so that the additional prism curve becomes a monotonically increasing curve. The additional prism curve of Sample 3 is as follows: Figure 5 As shown in (b). Figure 5 In (b), the solid line represents the additional prism curve on the principal meridian, and the dashed line represents the additional prism curve at the shifted umbilicus. On the principal meridian, the additional prism gradient on the asymptote is set to -0.077Δ / mm, and the maximum curvature is set to 0.0105Δ / mm. 2 Furthermore, it is set to have no reverse prism gradient. At the displaced umbilicus (umbilicus displacement = 5.5 mm), the additional prism gradient on the asymptote is set to -0.072Δ / mm, and the maximum curvature is set to 0.0100Δ / mm. 2 And it is set to not have a reverse prism gradient.

[0094] Sample 4 is configured as a progressive refractive power lens with an added inner prism to create a reverse prism gradient in the far-side region of the additional prism curve. The additional prism curve of Sample 4 is as follows: Figure 5 As shown in (c). In Figure 5In (c), the solid line represents the additional prism curve on the principal meridian, and the dashed line represents the additional prism curve at the shifted umbilicus. On the principal meridian, the additional prism gradient on the asymptote is set to -0.077Δ / mm, and the maximum curvature is set to 0.0088Δ / mm. 2 The reverse prism gradient is set to 0.0020Δ / mm, and the minimum value of the inner prism is -0.051Δ. At the displaced umbilicus (umbilicus displacement = 5.5mm), the additional prism gradient on the asymptote is set to -0.072Δ / mm, and the maximum curvature is set to 0.0082Δ / mm. 2 The gradient of the reverse prism is set to 0.0020Δ / mm, and the minimum value of the inner prism is set to -0.051Δ. That is, sample 4 satisfies all of the above conditions A, B, and C.

[0095] (2) Characteristic Evaluation

[0096] For samples 1 to 4, the degree distribution, astigmatism (AS) distribution, and third-order aberration (3rd) distribution were measured. The results for sample 1 are as follows: Figure 6 As shown in (a), the results for sample 2 are as follows: Figure 6 As shown in (b), the results for sample 3 are as follows. Figure 6 As shown in (c), the results for sample 4 are as follows: Figure 6 As shown in (d).

[0097] from Figure 6 (b) to Figure 6 (d) It can be seen that, compared with samples 2 and 3 whose additional prism curves do not have a reverse prism gradient, sample 4, whose additional prism curves have a reverse prism gradient, has reduced third-order aberrations.

[0098] Furthermore, regarding samples 2 to 4, taking into account the displacement of the umbilicus, the internal prism, power, astigmatism, and third-order aberrations were measured at the line-of-sight positions (the midpoint between the principal meridian and the displaced umbilicus). The results for sample 2 are as follows... Figure 7 As shown in (a), the results for sample 3 are as follows: Figure 7 As shown in (b), the results for sample 4 are as follows. Figure 7 As shown in (c). Furthermore, in Figure 7 (a) to Figure 7 In (c), the values ​​of diopter, astigmatism, and third-order aberration are expressed as the amount of change (in D) relative to the upper part of the spectacle lens (e.g., Y = 40 mm).

[0099] from Figure 7 (a) to Figure 7(c) It can be seen that a decrease in diopter occurs in the far-side region of samples 2 to 4. The diopter decrease for sample 2 is -0.34D, for sample 3 it is -0.28D, and for sample 4 it is -0.23D. That is, compared with samples 2 and 3, whose additional prism curves do not have a reverse prism gradient, sample 4, whose additional prism curves have a reverse prism gradient, has a reduced diopter decrease.

[0100] As can be seen from the above, it can be confirmed that by applying an appropriate amount of reverse prism gradient to the far-side region of the additional prism curve, the third-order aberration can be reduced, and the decrease in refractive power in the far-side region due to the shift in the line of sight is also reduced.

Claims

1. A spectacle lens, said spectacle lens having an internal prism added to bend light toward the wearer's nose. At least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, the spectacle lens has a reverse prism gradient with a different sign than the additional prism gradient on the asymptote. On the principal meridian of the spectacle lens and at the umbilicus point where it shifts towards the wearer's nose via the inner prism, the absolute value of the reverse prism gradient is greater than 0.014 times the absolute value of the additional prism gradient on the asymptote.

2. The spectacle lens according to claim 1, wherein, The absolute value of the reverse prism gradient is less than 0.00625Δ / mm.

3. The spectacle lens according to claim 2, wherein, On the principal meridian of the spectacle lens and at the umbilicus point that shifts towards the wearer's nose via the inner prism, the absolute value of the reverse prism gradient is less than 0.00625Δ / mm.

4. The spectacle lens according to any one of claims 1 to 3, wherein, The amount of internal prism added varies depending on the viewing distance.

5. The spectacle lens according to any one of claims 1 to 3, wherein, The difference between the maximum and minimum values ​​of the added internal prism is greater than 0.25Δ.

6. A method for manufacturing an eyeglass lens, wherein the eyeglass lens is supplemented with an internal prism that bends light toward the nose of the wearer, the manufacturing method comprising: At least in the far-side region of the additional prism curve, which is expressed as a function of the coordinates in the vertical direction of the spectacle lens, the prism design step involves designing the spectacle lens to have a prism gradient with a reverse prism gradient of a different sign than the additional prism gradient on the asymptotic band. In the prism design step, on the principal meridian of the spectacle lens and at the umbilicus point that shifts towards the wearer's nose via the inner prism, the absolute value of the reverse prism gradient is designed to be greater than 0.014 times the absolute value of the additional prism gradient on the asymptote.

Images