Eyeglass lenses and methods for manufacturing eyeglass lenses

Abstract

To provide a technique that can reduce the third-order aberration in a spectacle lens to which an in-prism for bending light in the direction of the nose of a wearer is added according to a viewing distance.SOLUTION: The present invention relates to a spectacle lens to which an in-prism for bending light in the direction of the nose of a wearer is added. The spectacle lens has a reverse prism inclination of a different sign from that of a signing prism inclination on a progressive zone in at least a long-distance region of the signing prism curve represented by the function of the coordinate in the vertical direction of the spectacle lens. The absolute value of the reverse prism inclination is larger than 0.014 times the absolute value of the signing prism inclination on the progressive zone.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to spectacle lenses and a method for manufacturing spectacle lenses.

Background Art

[0002] It is known that by adding an imprint prism that bends light in the direction of the wearer's nasal side by an amount corresponding to the diopter conversion value of the viewing distance, the reduction of the convergence power due to aging is supported and the fatigue level is reduced. Further, it is known that astigmatism occurs due to the torsion of the lens surface when adding an imprint prism according to the viewing distance. For example, in Patent Document 1, it is proposed to replace the addition prism curve with a smooth monotonically increasing curve in order to reduce aberration.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An embodiment of the present invention aims to provide a technique capable of reducing the tertiary aberration in a spectacle lens to which an imprint prism that bends light in the direction of the wearer's nasal side is added according to the viewing distance.

Means for Solving the Problems

[0005] A first aspect of the present invention is a spectacle lens to which an imprint prism that bends light in the direction of the wearer's nasal side is added, in at least the distance vision side region of the addition prism curve represented as a function of the vertical coordinate of the spectacle lens, having an inverse prism gradient with a sign different from that of the addition prism gradient on the progressive band, The absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone, in this spectacle lens.

[0006] A second aspect of the present invention is: The spectacle lens according to the first embodiment, wherein the absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone, both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in prism.

[0007] A third aspect of the present invention is: The spectacle lens according to the first or second embodiment, wherein the absolute value of the inverse prism gradient is less than 0.00625Δ / mm.

[0008] A fourth aspect of the present invention is: The spectacle lens according to the third embodiment, wherein the absolute value of the inverse prism gradient is less than 0.00625Δ / mm both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in prism.

[0009] A fifth aspect of the present invention is: The spectacle lens according to any one of the first to fourth embodiments described above, wherein the amount of added imperism changes depending on the viewing distance.

[0010] A sixth aspect of the present invention is: The spectacle lens according to any one of the first to fifth embodiments described above, wherein the difference between the maximum and minimum values ​​of the added imp prism amount is 0.25Δ or more.

[0011] A seventh aspect of the present invention is: A method for manufacturing spectacle lenses to which an imp prism is added that bends light toward the nose side of the wearer, The prism design process includes designing the add prism curve, which is expressed as a function of the vertical coordinates of the spectacle lens, to have an inverse prism gradient that has a different sign from the add prism gradient on the progressive band, at least in the distance-focusing region. In the prism design step, the method for manufacturing spectacle lenses is such that the absolute value of the reverse prism gradient is designed to be greater than 0.014 times the absolute value of the added prism gradient on the progressive zone.

Advantages of the Invention

[0012] According to one embodiment of the present invention, an in-prism that bends light in the direction of the wearer's nose side can reduce the third-order aberration in the added spectacle lens according to the viewing distance.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1(a) is an example of a diopter distribution diagram and an aberration distribution diagram without an in-prism, and FIG. 1(b) is an example of a diopter distribution diagram and an aberration distribution diagram with an in-prism. [Figure 2] FIG. 2(a) is a graph showing an example of an added prism curve represented as a function of the vertical coordinate of a spectacle lens, and FIG. 2(b) is a graph showing an example of the change in the sag amount Z around the principal meridian. [Figure 3] FIG. 3(a) is a graph showing an example of an added prism curve, FIG. 3(b) is a graph showing an example of the gradient (first derivative of the added prism curve) of the added prism curve, and FIG. 3(c) is a graph showing an example of the curvature (second derivative of the added prism curve) of the added prism curve. [Figure 4] FIG. 4(a) is a graph showing an example of an added prism curve when the value of q in formula (1) is changed, and FIG. 4(b) is a graph showing the relationship between the value of q and the minimum / maximum value of the gradient of the added prism curve and the maximum curvature of the added prism curve. [Figure 5] FIGS. 5(a) to (c) are graphs showing the added prism curves of Samples 2 to 4 according to the examples. [Figure 6] FIGS. 6(a) to (d) are diagrams showing the diopter distribution, the astigmatism aberration distribution, and the third-order aberration distribution of Samples 1 to 4 according to the examples. [Figure 7]Figures 7(a) to 7(c) are graphs showing the imprism, diopter, astigmatism, and coma aberration at the line-of-sight passing positions of Samples 2 to 4 according to the embodiment.

Mode for Carrying Out the Invention

[0014] <Findings Obtained by the Inventor> First, the findings obtained by the inventor will be described.

[0015] In this specification, in the vertical direction of the spectacle lens, the upper side is represented as positive and the lower side as negative, and in the horizontal direction of the spectacle lens, the ear side of the wearer is represented as positive and the nose side as negative. Also, the origin position is, for example, the lens center (at least any one of the geometric center, optical center, and centering center).

[0016] The methods described in Patent Document 1 and the like only optimize the astigmatism on the principal meridian generated by the torsion of the lens surface. However, after the imprism is added, since the line of sight does not pass through the original principal meridian in the first place, its significance can be said to be low. In this specification, the principal meridian refers to a line formed by gathering the portions of the spectacle lens through which the line of sight passes when the wearer moves the line of sight from above to below while wearing the spectacle lens. This principal meridian is the basis for designing the spectacle lens.

[0017] Fig. 1(a) is an example of a diopter (Power) distribution diagram and an astigmatism (AS) distribution diagram without imprism, and Fig. 1(b) is an example of a diopter distribution diagram and an astigmatism distribution diagram with imprism. In Fig. 1(a) and Fig. 1(b), the left side of the figure is the nose side. From Fig. 1(a) and Fig. 1(b), it can be seen that due to the imprism, the diopter has become asymmetric left and right, being low diopter in the nasal distance side region and high diopter in the nasal near side region. Also, it can be seen that the umbilical point (the region in the intermediate region and the near side region of the progressive power lens where the error of the astigmatism with respect to the prescription is relatively small) has shifted to the nose side.

[0018] The inventor's investigation revealed that the imprism shifts the nasal point towards the nose, causing the line of sight to also shift towards the nose. More specifically, it was found that the line of sight tends to pass through a point midway between the original principal meridian and the shifted nasal point. Based on this, the inventor discovered a new problem with eyeglass lenses that have an imprism added. That is, as the line of sight shifts towards the nose, there is a problem of insufficient power in the distance vision range (and excessive power in the near vision range). In addition, as the power changes at the line of sight's passage, there is also the problem of the added imprism amount being excessive in the distance vision range (and insufficient in the near vision range).

[0019] Figure 2(a) is a graph showing an example of an add prism curve expressed as a function of the vertical coordinates of the spectacle lens, and Figure 2(b) is a graph showing an example of the change in sag Z around the principal meridian. In Figure 2(a), the add prism curve is shown as a monotonically increasing curve (monotonically increasing downwards, and so on). In Figure 2(b), the solid line shows the sag Z at a position shifted 1 mm towards the ear from the principal meridian (X=1 mm), and the dashed line shows the sag Z at a position shifted 1 mm towards the nose from the principal meridian (X=-1 mm). The horizontal axis (Y) in Figures 2(a) and 2(b) represents the vertical coordinates of the spectacle lens.

[0020] In Figure 2(b), in region Z1, oblique astigmatism occurs because the gradient of the sag amount Z (dZ / dY) changes with the horizontal coordinate (X). As a result, aberration is added to the principal meridian, and the umbilicus point shifts towards the nose. On the other hand, in region Z2, the curvature of the sag amount Z (d 2 Z / dY 2 Third-order aberration occurs because the ) changes with the horizontal coordinate (X). Also, the power differs between the temporal and nasal sides, and the power is particularly smaller in the far-vision region on the nasal side.

[0021] The inventors conducted intensive studies, particularly focusing on the aforementioned third-order aberration. As a result, they discovered that the above-mentioned problem could be solved by designing the spectacle lens such that, at least in the distance-focusing region of the add prism curve, which is expressed as a function of the vertical coordinates of the spectacle lens, it has an inverse prism gradient that has a different sign from the add prism gradient on the progressive band.

[0022] Figure 3(a) is a graph showing an example of an add prism curve, Figure 3(b) is a graph showing an example of the slope of the add prism curve (first derivative of the add prism curve), and Figure 3(c) is a graph showing an example of the curvature of the add prism curve (second derivative of the add prism curve). In Figures 3(a) to 3(c), the dashed line shows the case where the add prism curve is a monotonically increasing curve, and the solid line shows the case where the add prism curve has an inverse prism slope. The horizontal axis in Figures 3(a) to 3(c) shows the vertical coordinates of the spectacle lens.

[0023] As can be seen from Figure 3(c), the absolute value of curvature is smaller when the add prism curve has an inverse prism gradient than when the add prism curve is a monotonically increasing curve. Therefore, the third-order aberration caused by the change in curvature can be reduced. By reducing the third-order aberration, the frequency fluctuation due to the shift in the line of sight's passage position can be reduced. In addition, when the add prism curve has an inverse prism gradient, the problem of excessive input prism in the far-field region can be resolved because a negative prism is added in the far-field region.

[0024] [Details of the Embodiments of the Invention] Next, one embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims, as shown in the claims.

[0025] In this specification, "horizontal direction" refers to the 0 or 180-degree direction in the definition of the astigmatism axis and prism base direction, and describes an example where it coincides with the direction of the horizontal reference line connecting two alignment reference marks (so-called hidden marks) for framing. In this embodiment, the horizontal reference line is a line extending horizontally midway between the upper and lower vertices of the spectacle lens (a round lens before framing). In this embodiment, an example is described in which the hidden marks are positioned such that the principal meridian passes through the center of the horizontal reference line connecting the two hidden marks.

[0026] Furthermore, in this embodiment, the principal meridian in the progressive power lens may be the line connecting the distance power measurement point and the near power measurement point.

[0027] <First Embodiment of the Invention> (1) Construction of eyeglass lenses First, the configuration of the spectacle lens of this embodiment will be described. The spectacle lens of this embodiment is a progressive power lens in which a portion or all of a single lens includes a portion (progressive zone) in which the refractive power changes continuously. The spectacle lens has an optical surface formed on the side of the object based on a predetermined design. The spectacle lens may include not only so-called finished lenses that also have a predetermined optical surface on the side of the eyeball, but also semi-finished lenses in which a finished lens can be obtained by further polishing the side of the eyeball according to the prescription. In addition, lenses generally called bifocal lenses, intermediate-distance lenses, near-distance lenses, and accommodative support lenses are also included in progressive power lenses. The addition of the in prism, described later, may be on either the object side or the eyeball side, and there are no particular restrictions on whether it is on the progressive surface side or not.

[0028] The eyeglass lenses of this embodiment have an in prism added that bends light toward the wearer's nose, depending on the viewing distance. In other words, the amount of added in prism in the eyeglass lenses of this embodiment changes depending on the viewing distance, and for example, the amount of in prism in the near-vision region is greater than the amount of in prism in the far-vision region. The in prism is useful, for example, when a wearer with weak convergence power views a nearby object. In the eyeglass lenses of this embodiment, for example, it is preferable that the difference between the maximum and minimum values ​​of the added in prism is 0.25Δ (prism diopter) or more, and more preferably 1Δ or more. In this case, the effect of the present invention is more pronounced because the power fluctuations associated with the shift in the line of sight passing position described above are more likely to affect how the eyeglass lenses look. The upper limit of the difference between the maximum and minimum values ​​of the added in prism is not particularly limited, but for example, it is 6Δ or less (or 2Δ or less).

[0029] The eyeglass lens of this embodiment has an inverse prism gradient that has a different sign from the add prism gradient on the progressive zone in at least the distance-vision region of the add prism curve, which is expressed as a function of the vertical coordinates of the eyeglass lens. In this specification, the distance-vision region of the add prism curve means the region above the position (or progressive zone) where the gradient of the add prism curve is maximum, and the near-vision region means the region below the position (or progressive zone) where the gradient of the add prism curve is maximum. Furthermore, the add prism gradient on the progressive zone may be the maximum value of the gradient of the add prism curve.

[0030] However, simply applying an inverse prism gradient to the distance-focusing region of the add prism curve may not reduce the absolute value of the curvature of the add prism curve compared to the case where the add prism curve is a monotonically increasing curve. In order to reduce the absolute value of the curvature of the add prism curve and reduce third-order aberration, it is necessary to appropriately control the amount of inverse prism gradient applied. Specifically, the spectacle lens of this embodiment preferably satisfies the following conditions A, B, and C.

[0031] (Condition A) The add prism curve illustrated in Figure 3(a) can be expressed by the following sigmoid function (Equation (1)). Below, we will explain the minimum amount of inverse prism gradient required to reduce third-order aberration, using the case where the add prism curve is represented by a sigmoid function as an example.

number

[0032] Figure 4(a) is a graph showing an example of the add prism curve when the value of q in equation (1) is varied. As shown in Figure 4(a), when q=0, the add prism curve is a monotonically increasing curve, but when q=0.7 and q=1.1, it can be seen that the add prism curve is given an inverse 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 add prism curve, and the maximum curvature of the add prism curve. In Figure 4(b), the solid line shows the minimum / maximum value of the gradient of the add prism curve, and the dashed line shows the maximum curvature of the add prism curve (relative value with q=0 set to 1).

[0033] A positive minimum / maximum gradient of the add prism curve means that the minimum and maximum gradients of the add prism curve have the same sign. In other words, region Z3 shown in Figure 4(b) is a region where the add prism curve does not have an inverse prism gradient. On the other hand, regions Z4 and Z5, where the minimum / maximum gradient of the add prism curve is negative, are regions where the add prism curve has an inverse prism gradient. Note that when the add prism curve has an inverse prism gradient, the minimum gradient of the add prism curve can be considered as the inverse prism gradient, and therefore the minimum / maximum gradient of the add prism curve can also be expressed as the inverse prism gradient / add prism gradient on the progressive zone.

[0034] As shown in Figure 4(b), in region Z4, the maximum curvature of the add prism curve is greater than when q=0. In other words, region Z4 is a region where the add prism curve has an inverse prism gradient, but the absolute value of the curvature of the add prism curve is not smaller than when the add prism curve is a monotonically increasing curve. For example, the add prism curve with q=0.7 shown in Figure 4(a) has a larger absolute value of curvature than the add prism curve with q=0 (a monotonically increasing curve).

[0035] On the other hand, in region Z5, the maximum curvature of the add prism curve is smaller than when q=0. In other words, when q>0.9 (region Z5), the absolute value of the curvature of the add prism curve is smaller compared to when the add prism curve is a monotonically increasing curve. For example, the add prism curve for q=1.1 shown in Figure 4(a) has a smaller absolute value of curvature than the add prism curve for q=0 (a monotonically increasing curve).

[0036] In region Z5, there is a one-to-one correspondence between the value of q and the minimum / maximum values ​​of the gradient of the add prism curve. Therefore, q > 0.9 can also be expressed as the minimum / maximum values ​​of the gradient of the add prism curve being less than -0.014. The minimum / maximum values ​​of the gradient of the add prism curve can also be expressed as the inverse prism gradient / the add prism gradient on the progressive zone. Thus, in region Z5, the absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone. Consequently, when the absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone, the absolute value of the curvature of the add prism curve becomes smaller compared to the case where the add prism curve is a monotonically increasing curve, and third-order aberrations can be reduced.

[0037] (Condition B) Under condition A, it was explained that third-order aberration can be reduced when the absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone. On the other hand, if the absolute value of the inverse prism gradient is too large, oblique astigmatism may occur, potentially adversely affecting the visual clarity of the spectacle lens. Below, we will describe the preferred range of the inverse prism gradient to prevent oblique astigmatism caused by the inverse prism gradient from adversely affecting the visual clarity of the spectacle lens.

[0038] Generally, astigmatism is prescribed in units of 0.25D, so if the astigmatism is less than half of that, 0.125D, the effect on the visual clarity of eyeglass lenses is considered negligible. From the relationship between the amount of astigmatism caused by the inverse prism gradient (D) = 2 × 10 × inverse prism gradient (Δ / mm), it can be said that if the absolute value of the inverse prism gradient is less than 0.00625Δ / mm, the amount of astigmatism caused by the inverse prism gradient can be kept below 0.125D. Therefore, in order to prevent oblique astigmatism caused by the inverse prism gradient from adversely affecting the visual clarity of eyeglass lenses, it is preferable that the absolute value of the inverse prism gradient be less than 0.00625Δ / mm.

[0039] (Condition C) The conditions for the inverse prism gradient described in conditions A and B are preferably satisfied both on the principal meridian of the spectacle lens and on the line parallel to the principal meridian that passes through the point furthest from the principal meridian among the umbilical points shifted towards the wearer's nose by the in prism. To avoid complexity, in this specification, the line parallel to the principal meridian that passes through the point furthest from the principal meridian among the umbilical points shifted towards the wearer's nose by the in prism is also referred to as the umbilical point shifted towards the wearer's nose by the in prism or the shifted umbilical point. In other words, both on the principal meridian of the spectacle lens and on the umbilical point shifted towards the wearer's nose by the in prism, the absolute value of the inverse prism gradient is preferably greater than 0.014 times the absolute value of the add prism gradient on the progressive zone. Furthermore, it is preferable that the absolute value of the inverse prism gradient is less than 0.00625Δ / mm both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in-prism. In this embodiment, the umbilical point is defined as the region enclosed by the contour lines with the smallest astigmatism in the astigmatism distribution diagram. However, this does not apply to regions where astigmatism is locally reduced due to processing errors, etc.

[0040] As mentioned above, when the navel point is shifted towards the nose, the line of sight tends to pass through a point midway between the original principal meridian and the shifted navel point. Therefore, satisfying condition A (or condition B) both on the principal meridian of the spectacle lens and on the navel point shifted towards the wearer's nose by the imp prism means that the effect of satisfying condition A (or condition B) is maintained even if the line of sight passes through the lens, shifted towards the nose.

[0041] Next, we will explain the umbilical point shift amount, which indicates how much the umbilical point shifts from the original principal meridian when the in prism shifts it towards the nose. The umbilical point shift amount is expressed as the amount of astigmatism generated by the in prism (D) / the horizontal astigmatism gradient of the spectacle lens (D / mm). Furthermore, from the relationship between the amount of astigmatism generated by the in prism (D) = 2 × 10 × the add prism gradient on the progressive zone (Δ / mm) and the horizontal astigmatism gradient of the spectacle lens (D / mm) = 2 × the add power gradient (D / mm), the umbilical point shift amount (mm) can be calculated using the relationship between the add prism gradient on the progressive zone (Δ / mm) / the add power gradient (D / mm). By shifting the principal meridian parallel to the nose by the maximum value of the umbilical point shift amount, we can define "the umbilical point shifted towards the wearer's nose by the in prism".

[0042] Furthermore, the near-field region of the join prism curve may or may not have an inverse prism gradient. If an inverse prism gradient is present in the near-field region, it is preferable that the inverse prism gradient in the near-field region also satisfies the above-mentioned conditions A, B, and C. In addition, as shown by the solid line in Figure 3(a), the inverse prism gradients of the far-field region and the near-field region may be symmetrical.

[0043] (2) Method for manufacturing eyeglass lenses The method for manufacturing eyeglass lenses according to this embodiment will be described below. Note that in the following description, known techniques may be adopted for matters not described in this specification.

[0044] (preparation process) The preparation phase involves preparing for the subsequent design phase. This preparation primarily involves obtaining the information necessary for designing eyeglass lenses. Information related to eyeglass lenses can be broadly divided into item-specific information, which is data specific to the lens item, and wearer-specific information, which is data specific to the wearer. Item-specific information includes information such as the refractive index n of the lens material and progressive surface design parameters represented by the progressive zone length. Wearer-specific information includes information such as distance power (spherical power S, astigmatism power C, astigmatism axis AX, prism power P, prism base direction PAX, etc.), add 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, curvature angle, vertex distance, etc.).

[0045] (design process) 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 in which the shape of the in prism is designed. In the prism design process, the shape of the in prism is designed such that, at least in the distance-focusing region of the add prism curve, which is expressed as a function of the vertical coordinates of the spectacle lens, it has an inverse prism gradient that has a different sign from the add prism gradient on the progressive band.

[0046] In the prism design process, it is preferable to design the shape of the in-prism so as to satisfy the above-mentioned conditions A, B, and C. In other words, in the prism design process, it is preferable to design the absolute value of the inverse prism gradient to be greater than 0.014 times the absolute value of the add prism gradient on the progressive zone. Furthermore, it is preferable to design the absolute value of the inverse prism gradient to be greater than 0.014 times the absolute value of the add prism gradient on the progressive zone both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in-prism. Furthermore, it is preferable to design the absolute value of the inverse prism gradient to be less than 0.00625Δ / mm. Furthermore, it is preferable to design the absolute value of the inverse prism gradient to be less than 0.00625Δ / mm both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in-prism. By designing the shape of the in-prism in this way, the various effects described in (1) Spectacle Lens Configuration can be obtained. Furthermore, this invention can be used not only as a method for manufacturing eyeglass lenses, but also as a method for designing eyeglass lenses.

[0047] (manufacturing process) In the manufacturing process, eyeglass lenses are produced based on the design results from the design phase. Regarding the specific manufacturing method, known methods may be adopted. For example, the design data obtained in the design phase may be input into a processing machine, and the lens blanks may be processed to produce eyeglass lenses.

[0048] Of course, you may add other steps (such as cleaning or coating processes) as needed, in addition to the steps mentioned above.

[0049] Through the above process, eyeglass lenses with reduced third-order aberrations can be manufactured.

[0050] <Other embodiments of the present invention> Although embodiments of the present invention have been specifically described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0051] For example, the amount of inward shift and the fitting point of a progressive power lens may be adjusted taking into account the umbilical point shift amount mentioned above. [Examples]

[0052] Next, embodiments of the present invention will be described. These embodiments are examples of the present invention, and the present invention is not limited to these embodiments.

[0053] (1) Fabrication of eyeglass lenses First, samples 1-4 were prepared as eyeglass lenses, as shown below.

[0054] Sample 1 was a progressive power lens without an in-prism. The add power gradient of the progressive zone was set to -0.141 D / mm. The add power gradient of the progressive zone was the same for Samples 2 to 4 below.

[0055] Sample 2 was a progressive refractive power lens with an in-prism proportional to the viewing distance. The add-on prism curve for Sample 2 is shown in Figure 5(a). In Figure 5(a), the solid line shows the add-on prism curve on the principal meridian, and the dashed line shows the add-on prism curve on the shifted umbilicus point. On the principal meridian, the add-on prism gradient on the progressive zone is -0.086Δ / mm, and the maximum curvature is 0.0112Δ / mm. 2 It was assumed that there was no inverse prism gradient. On the shifted umbilicus point (umbilicus point shift amount = 6.1 mm), the add prism gradient on the progressive band was -0.084 Δ / mm, and the maximum curvature was 0.0109 Δ / mm. 2 It was assumed that it did not have an inverse prism gradient.

[0056] Sample 3 was a progressive refractive power lens with an in prism added so that the add prism curve was a monotonically increasing curve. The add prism curve of Sample 3 is shown in Figure 5(b). In Figure 5(b), the solid line shows the add prism curve on the principal meridian, and the dashed line shows the add prism curve on the shifted umbilicus point. On the principal meridian, the add prism gradient on the progressive zone is -0.077Δ / mm, and the maximum curvature is 0.0105Δ / mm. 2It was assumed that there was no inverse prism gradient. On the shifted umbilicus point (umbilicus point shift amount = 5.5 mm), the add prism gradient on the progressive band was -0.072 Δ / mm, and the maximum curvature was 0.0100 Δ / mm. 2 It was assumed that it did not have an inverse prism gradient.

[0057] Sample 4 is a progressive refractive power lens with an in-prism added so that the add-on prism curve has an inverse prism gradient in the far-field region of the add-on prism curve. The add-on prism curve of Sample 4 is shown in Figure 5(c). In Figure 5(c), the solid line shows the add-on prism curve on the principal meridian, and the dashed line shows the add-on prism curve on the shifted umbilicus point. On the principal meridian, the add-on prism gradient on the progressive zone is -0.077Δ / mm, and the maximum curvature is 0.0088Δ / mm. 2 The inverse prism gradient was set to 0.0020Δ / mm, and the minimum value of the in-prism was set to -0.051Δ. On the shifted umbilicus point (umbilicus point shift amount = 5.5 mm), the add prism gradient on the progressive band was -0.072Δ / mm, and the maximum value of curvature was 0.0082Δ / mm. 2 The inverse prism gradient was set to 0.0020Δ / mm, and the minimum value of the in prism was set to -0.051Δ. In other words, sample 4 was designed to satisfy all of the above conditions A, B, and C.

[0058] (2) Characterization For samples 1-4, the power distribution, astigmatism (AS) distribution, and third-order aberration (3rd) distribution were measured. The results for sample 1 are shown in Figure 6(a), the results for sample 2 in Figure 6(b), the results for sample 3 in Figure 6(c), and the results for sample 4 in Figure 6(d).

[0059] As can be seen from Figures 6(b) to (d), sample 4, which has an inverse prism gradient in its add prism curve, showed reduced third-order aberration compared to samples 2 and 3, which do not have an inverse prism gradient in their add prism curves.

[0060] Furthermore, for samples 2-4, the imp prism, power, astigmatism, and cubic aberration were measured at the line of sight passing position (an intermediate position between the principal meridian and the shifted umbilicus), taking into account the shift of the umbilicus point. The results for sample 2 are shown in Figure 7(a), the results for sample 3 are shown in Figure 7(b), and the results for sample 4 are shown in Figure 7(c). In Figures 7(a)-(c), the values ​​for power, astigmatism, and cubic aberration are shown as the amount of change (unit: D) ​​relative to the top of the spectacle lens (e.g., Y=40mm).

[0061] As can be seen from Figures 7(a) to (c), a decrease in frequency occurred in the far-field region of samples 2 to 4. The decrease in frequency for sample 2 was -0.34D, for sample 3 it was -0.28D, and for sample 4 it was -0.23D. In other words, sample 4, which has an inverse prism gradient in its add prism curve, showed a reduced decrease in frequency compared to samples 2 and 3, which do not have an inverse prism gradient in their add prism curves.

[0062] Based on the above, we confirmed that by applying an appropriate amount of inverse prism gradient in the distance vision region of the add prism curve, third-order aberrations are reduced, and the decrease in power in the distance vision region due to the shift of the line of sight passage towards the nose is also reduced.

Claims

1. Eyeglass lenses with an imp prism added that bends light toward the wearer's nose, In at least the distance-focusing region of the add prism curve, which is expressed as a function of the vertical coordinates of the aforementioned spectacle lens, it has an inverse prism gradient that has a different sign from the add prism gradient on the progressive band. At both the principal meridian of the spectacle lens and the nasal point shifted towards the wearer's nose by the in-prism, the absolute value of the inverse prism gradient is greater than 0.014 times the absolute value of the add prism gradient on the progressive zone. An eyeglass lens wherein the addition prism curve is a monotonically increasing curve, and the absolute value of the curvature of the addition prism curve is smaller than the absolute value of the curvature of the addition prism curve when the absolute value of the curvature of the addition prism curve is smallest.

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

3. The spectacle lens according to claim 2, wherein the absolute value of the inverse prism gradient is less than 0.00625Δ / mm both on the principal meridian of the spectacle lens and on the umbilical point shifted toward the wearer's nose by the in prism.

4. An eyeglass lens according to any one of claims 1 to 3, wherein the amount of added imp prism changes depending on the viewing distance.

5. An eyeglass lens according to any one of claims 1 to 4, wherein the difference between the maximum and minimum values ​​of the added imp prism amount is 0.25Δ or more.

6. A method for manufacturing spectacle lenses to which an imp prism is added that bends light toward the nose side of the wearer, The prism design process includes designing the add prism curve, which is expressed as a function of the vertical coordinates of the spectacle lens, to have an inverse prism gradient that has a different sign from the add prism gradient on the progressive band, at least in the distance-focusing region. A method for manufacturing eyeglass lenses, wherein in the prism design process, the absolute value of the inverse prism gradient is designed to be greater than 0.014 times the absolute value of the add prism gradient on the progressive zone, both on the principal meridian of the eyeglass lens and on the umbilical point shifted toward the wearer's nose by the in prism, and the absolute value of the curvature of the add prism curve is smaller than the case in which the add prism curve is a monotonically increasing curve and the absolute value of the curvature of the add prism curve is smallest.

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