JP2015079126A - Spectacle lens design method, spectacle lens manufacturing method, and spectacle lens selection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce glare due to internal reflection of a spectacle lens.SOLUTION: A spectacle lens design method designs a spectacle lens including: an external surface which serves as a refracting interface on an object side in a wearing state, and an inner surface which serves as a refracting interface on an eyeball side in the wearing state. The spectacle lens design method determines a shape of the spectacle lens in consideration of a beam of light reflected on the spectacle lens and passing through a wearing person's iris.

Description

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

  The power of the spectacle lens mainly includes the refractive index of the optical material forming the spectacle lens and the thickness of the spectacle lens, as well as the curvature and wearing state of the outer surface (hereinafter referred to as the outer surface) which becomes the refractive surface on the object side in the wearing state. And the curvature of the inner surface (hereinafter referred to as the inner surface) serving as a refractive surface on the eyeball side. For this reason, various combinations of the curvatures of the outer surface and the inner surface for obtaining a spectacle lens having a predetermined power can be considered.

  In order to ensure the required optical performance of the spectacle lens, in particular to reduce the astigmatism acting on the eye when the wearer sees it through the side part away from the optical axis of the spectacle lens, for example, a Chelning ellipse It is desirable to select the combination of curvatures obtained by However, in practice, a combination different from the optimal combination of curvatures due to the Chelning ellipse is often selected because of the appearance and manufacturing convenience of the spectacle lens. As a result, the optical performance of the spectacle lens is degraded, but in order to compensate for this decline, various design technologies that optimize the surface shape of the spectacle lens in consideration of various conditions such as the prescription power of the spectacle lens Is disclosed (see Patent Document 1).

Japanese Patent No. 4361254

  By the way, in most eyeglass lenses currently on the market, a metal oxide such as SiO2 or ZrO2 or a metal fluoride such as CaF2 or MgF2 having a low refractive index is used on the outer surface of the eyeglass lens by using a method such as vacuum deposition or sputtering. A thin film is formed. Depending on the refractive index of the optical material, this thin film reduces the reflectance of the spectacle lens, which is usually about 8 to 12%, to about 0.5 to 4% when there is no thin film. As a result, it is possible to prevent the spectacle lens from appearing to shine white in appearance and the light reflected from the inner surface of the spectacle lens from being bothered.

  However, in the case of a strong light source such as the sun, it is possible to prevent light reflected from the inner surface of the spectacle lens from reaching the eye even if the reflectance of the spectacle lens is reduced by the thin film (antireflection coating). Have difficulty. Therefore, when the wearer is looking at an object in an arbitrary direction, light from the rear of the wearer is reflected by the inner surface of the spectacle lens, apart from the light from the object that is transmitted through the spectacle lens. In some cases, it reaches the wearer's retina and the wearer feels dazzled or makes it difficult to recognize the object.

The spectacle lens design method according to claim 1 is a spectacle lens design method for designing a spectacle lens having an outer surface that is a refractive surface on the object side in a worn state and an inner surface that is a refractive surface on the eyeball side in a worn state. The shape of the spectacle lens is determined in consideration of the light beam reflected by the spectacle lens and passing through the iris of the wearer.
A spectacle lens manufacturing method according to a thirteenth aspect is characterized by manufacturing a spectacle lens designed by the spectacle lens designing method according to any one of the first to twelfth aspects.
The spectacle lens selection method according to claim 14 is a spectacle lens selection method for selecting a spectacle lens having an outer surface that is a refractive surface on the object side in a worn state and an inner surface that is a refractive surface on the eyeball side in a worn state. Thus, the spectacle lens is selected in consideration of the light beam reflected by the spectacle lens and passing through the iris of the wearer.

  ADVANTAGE OF THE INVENTION According to this invention, the glare by the internal reflection of a spectacle lens can be reduced.

It is a flowchart explaining the design procedure of a spectacle lens. It is a figure explaining the relative positional relationship of a wearer's head and a light source. It is a figure explaining the relationship between the maximum eyeball rotation angle and the minimum curvature of the inner surface. It is a figure explaining the relationship between the maximum eyeball rotation angle, the pupil diameter, and the minimum curvature of the inner surface. 10 is a flowchart illustrating a spectacle lens design procedure in Modification 1. 10 is a flowchart illustrating a procedure for selecting a spectacle lens in Modification 2.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, prior to the description of the present embodiment, a technique that is a premise of the present embodiment will be described. The refractive power of a spectacle lens is generally expressed in units of diopters (hereinafter referred to as “D”). The refractive power at the lens surface of the spectacle lens, that is, the surface refractive power φ (D) is ρ (unit: 1 / m) as the main curvature of the lens surface, and n is the refractive index of the optical material forming the spectacle lens. The outer surface is represented by the following formula (1), and the inner surface is represented by the following formula (2). The case where the main curvature ρ is positive is a case where the center of curvature of the lens surface is on the eyeball side with respect to the lens surface (that is, a case where it is convex on the object side). The case where the main curvature ρ is negative is a case where the center of curvature of the lens surface is on the object side with respect to the lens surface (that is, a case where the lens surface is convex on the eyeball side).
φ (outer surface) = (n−1) × ρ (1)
φ (inner surface) = (1-n) × ρ (2)

  In general, the surface refractive power value on the lens surface of a spectacle lens often takes a positive value for the outer surface and a negative value for the inner surface.

  In addition, in a spectacle lens such as a progressive power lens, a semi-finished lens (semi-finish lens) in which one lens surface (hereinafter referred to as a processing surface) of the outer surface and the inner surface is processed in advance is prepared in advance. Many. In this case, a spectacle lens is generated by processing the other lens surface that has not been processed in advance (hereinafter referred to as a prescription surface) in accordance with the prescription conditions of the wearer. The prescription condition is a condition for determining the specs of the spectacle lens, and is, for example, a prescription power, an astigmatism power, an astigmatism axis degree, and an addition power. Further, the shape of the processed surface is a spherical surface, an aspherical surface, or a progressive surface shape, and the shape of the prescription surface is an aspherical surface shape or a free-form surface shape. In many cases, the outer surface is a processed surface and the inner surface is a prescription surface.

When the lens surface is formed in a complicated shape such as an aspherical surface or a free-form surface, the curvature and surface refractive power of the lens surface are the average curvature ρa and the surface average at arbitrary points on the lens surface, respectively. Expressed with refractive power φa. The average curvature ρa at an arbitrary point on the lens surface is expressed by the following formula (3), where ρmax is the maximum principal curvature and ρmin is the minimum principal curvature at that point. Further, the surface average refractive power φa at the outer surface is expressed by the following equation (4), and the surface average refractive power φa at the inner surface is expressed by the following equation (5).
ρa = (ρmax + ρmin) / 2 (3)
φa (outer surface) = (n−1) × ρa (4)
φa (inner surface) = (1-n) × ρa (5)

  Also, when the lens surface shape is aspherical or free-form surface, the average curvature and surface average refractive power differ depending on the coordinates on the lens surface. In many cases, it is defined by the surface average refractive power at the reference coordinates for measuring.

  In conventional spectacle lenses, for the reasons of manufacturing or appearance, after determining the surface refractive power of the outer surface (processed surface), the shape of the inner surface (prescription surface) is processed according to prescription conditions. Yes. For this reason, it is difficult to control internal reflection by the shape of the internal surface.

  Therefore, in this embodiment described below, first, the curvature of the inner surface is determined so as to prevent the light beam reflected by the inner surface of the spectacle lens from reaching the retina of the wearer, and then the curvature of the outer surface (surface refraction). Power). Thereby, the spectacle lens which reduced the influence of internal reflection can be designed now. Hereinafter, the spectacle lens design method in the present embodiment will be described focusing on this point.

  In the spectacle lens designed in this embodiment, the outer surface has a positive refractive power and the inner surface has a negative refractive power. That is, the spectacle lens designed in the present embodiment is a meniscus lens in which both the outer surface and the inner surface are convex on the object side. Therefore, in the spectacle lens designed in the present embodiment, the outer surface curvature ρ1 and the inner surface curvature ρ2 take positive values.

  Further, at least one curvature reference coordinate Pi (xi, yi) is set on the spectacle lens. The curvature reference coordinate Pi (xi, yi) is at least one of the geometric center coordinate of the spectacle lens, the reference coordinate for measuring the power of the spectacle lens, the distance reference point, and the near reference point. Note that the distance reference point is a reference point for measuring the distance power in the distance portion region (region suitable for far vision) of progressive refractive power. The near reference point is a reference point for measuring the near power in the near power region (region suitable for near vision) of progressive refractive power.

In the present embodiment, a value obtained by averaging the average curvature at each curvature reference coordinate Pi on the outer surface is used as the curvature ρ1 of the outer surface of the spectacle lens. That is, the curvature ρ1 of the outer surface is the maximum main curvature at each curvature reference coordinate Pi (xi, yi) on the outer surface when m (m ≧ 1) curvature reference coordinates Pi (xi, yi) are set. Is represented by the following equation (6), where ρ1max (xi, yi) is the minimum principal curvature and ρ1min (xi, yi). In the present embodiment, as the curvature ρ2 of the inner surface of the spectacle lens, a value obtained by averaging the average curvature at each curvature reference coordinate Pi on the inner surface is used. That is, the curvature ρ2 of the inner surface is the maximum main curvature at each curvature reference coordinate Pi (xi, yi) on the inner surface when m (m ≧ 1) curvature reference coordinates Pi (xi, yi) are set. Is represented by the following formula (7), where ρ2max (xi, yi) is the minimum principal curvature and ρ2min (xi, yi).

  Next, the design procedure of the spectacle lens will be described using the flowchart shown in FIG. In step S1, the wearer's wearing conditions are determined. The wearing conditions are information on the wearer's biological information and the relative positional relationship between the wearer and the glasses. For example, the wearer's head shape, interpupillary distance, pupil diameter, axial length, and macular shape. Corneal apex distance, eyeball rotation angle, frame shape, and the like. As a method for determining the wearing condition, for example, a method of measuring using a three-dimensional shape measuring device, a line-of-sight detection device, a fundus inspection device, or the like, a method of determining with reference to statistical information, and the like can be considered.

  In step S2, based on the wearing conditions determined in step 1, the inner surface has a negative refractive power, and the light beam from the light source at an arbitrary position behind the wearer is reflected after being reflected by the inner surface of the spectacle lens. In consideration of whether or not the person reaches the retina, the curvature of the inner surface of the spectacle lens is determined so as to prevent the light from reaching the retina. As a method of determining the curvature of the inner surface, for example, a method of performing a ray tracing simulation using a computer, or a relational expression or a table indicating a relationship between the wearing condition and a curvature that prevents inner reflection is determined in advance. Possible ways to do this. Details will be described later.

  In step S3, prescription conditions for the wearer are determined. The prescription conditions are determined by a general method such as optometry.

  In step S4, the curvature of the outer surface that satisfies the prescription conditions determined in step S3 is determined based on the curvature of the inner surface determined in step S2 and the refractive index of the optical material forming the spectacle lens.

  In step S5, a spectacle lens designed in the steps up to step S4, that is, a spectacle lens whose inner surface has the curvature determined in step S2 and whose outer surface has the curvature determined in step S4 is manufactured.

  Next, the result of a ray tracing simulation performed to obtain the curvature of the inner surface so that the light beam reflected by the inner surface of the spectacle lens does not reach the wearer's retina will be described. This ray tracing simulation was performed by arranging a wearer, a spectacle lens, and a light source in a virtual space. FIG. 2 is a diagram for explaining the relative positional relationship between the head 10 of the wearer and the light source 20 in the ray tracing simulation. FIG. 2A is a view as seen from the left hand side of the wearer, and FIG. 2B is a view as seen from directly above the wearer. As the wearing conditions used in the ray tracing simulation, the size of the head shape of the wearer is described in “Makiko Kawachi and Masaaki Mochimaru, 2008: Japanese Head Dimensions Database 2001, National Institute of Advanced Industrial Science and Technology H16PRO-212”. The head model generated with reference to is used. The distance between the pupils of the wearer was 63 mm, the pupil diameter was 5 mm, the axial length was 24 mm, and the corneal vertex distance was 12 mm. General shapes were used for the macular shape of the wearer and the frame shape of the glasses.

  In addition, the light source 20 was disposed relatively behind the wearer on an infinite sphere centered on the head 10 of the wearer. Centering on the wearer's head 10, three-dimensional coordinates were assumed with the horizontal rear as the x-axis, the vertical upper direction as the y-axis, and the horizontal right-hand direction as the z-axis. In the xy plane, the counterclockwise rotation angle around the z axis (rotation angle from the x axis) is α, and in the xz plane, the counterclockwise rotation angle around the y axis (rotation angle from the x axis) is β. It was. About the light source 20, the point light source was arrange | positioned in the arbitrary positions used as -90 degrees <= alpha <= 90 degrees and -90 degrees <= beta <= 90 degrees.

  The inner surface of the spectacle lens was formed into a spherical shape that totally reflects light rays, and the ray tracing simulation was performed by continuously changing the curvature of the inner surface. Then, when the wearer's eyeball is arbitrarily rotated below the maximum eyeball rotation angle, the light beam reaches the wearer's macula or macular fovea by internal reflection of the spectacle lens regardless of the position of the light source The minimum curvature of the inner surface, which is a consistent boundary value, was obtained. In addition, ray tracing simulation was performed by changing the maximum eye rotation angle, and the relationship between the maximum eye rotation angle and the minimum curvature of the inner surface was obtained.

  FIG. 3 is a graph showing the relationship between the maximum eyeball rotation angle and the minimum curvature of the inner surface, obtained as a result of the ray tracing simulation. The horizontal axis of the graph shown in FIG. 3 indicates the maximum eyeball rotation angle, and the vertical axis indicates the minimum curvature of the inner surface. In the graph shown in FIG. 3, the solid line L1 indicates the minimum curvature of the inner surface where the light beam does not reach the wearer's macular portion, and the broken line L2 indicates that the light beam does not reach the fovea fovea fovea. Indicates the minimum curvature of the inner surface.

  The tighter the curve on the inner surface of the spectacle lens, the more light rays that are incident on the inner surface of the spectacle lens from the light source behind the wearer are blocked by the wearer's head. You can avoid reaching the fossa. Therefore, if the inner curvature of the spectacle lens is determined to be a value that is equal to or greater than the minimum curvature of the inner surface corresponding to the maximum eyeball rotation angle of the wearer (that is, a value with which the curve becomes tighter), the light beam caused by the internal reflection of the spectacle lens Can be prevented from reaching the wearer's retina. Since it is preferable that the inner surface is as curved as possible from the viewpoint of manufacturing and appearance, it is preferable to determine the minimum curvature as the curvature of the inner surface of the spectacle lens.

  Further, from the graph shown in FIG. 3, the minimum curvature of the inner surface that becomes a boundary from which the light beam reflected by the inner surface of the spectacle lens does not reach the retina of the wearer increases as the maximum eyeball rotation angle increases (the curve becomes tighter). ) As described above, the minimum curvature of the inner surface may be obtained using the maximum eyeball rotation angle. However, it is generally considered that there are few opportunities to watch the eyeball while rotating the eyeball to the maximum in daily life. Therefore, the minimum curvature of the inner surface may be obtained using not the maximum eyeball rotation angle possible for the wearer (maximum eyeball rotation angle) but the eyeball rotation angle (ordinary eyeball rotation angle) that is normally used by the wearer. Since the normal eyeball rotation angle is smaller than the maximum eyeball rotation angle, the minimum curvature of the inner surface is correspondingly reduced, and the curve of the inner surface can be made gentler. The common eyeball rotation angle may be measured by, for example, a line-of-sight detection device.

  In addition, it can be seen from the graph shown in FIG. 3 that the minimum curvature at which the light beam due to internal reflection does not reach the macula is smaller (curve curving) than the minimum curvature at which the central fovea does not reach. In other words, the dazzling due to the internal reflection can be further reduced if the light beam due to the internal reflection does not reach the entire macula portion, but the curve of the internal surface becomes tight accordingly. Therefore, if the minimum curvature at which light does not reach the macular fovea, which is the portion with the highest visual acuity in the macula, is used, the inner surface curve can be made as much as possible while reducing the glare caused by the inner reflection to some extent. In determining the curvature of the inner surface, the designer may appropriately select which of the minimum curvature that does not allow light to reach the macula and the minimum curvature that does not reach the central fovea of the macula.

  Furthermore, although the wearer's pupil diameter is 5 mm in the ray tracing simulation, FIG. 4 shows the results of the ray tracing simulation even under the condition that the pupil diameter is 3 mm or 1 mm. In the graph shown in FIG. 4, the solid line L1 indicates the result of the pupil diameter 5 mm, the broken line L3 indicates the result of the pupil diameter 3 mm, and the dotted line L4 indicates the result of the pupil diameter 1 mm. In addition, in FIG. 4, the minimum curvature of the inner surface in which the light ray by inner surface reflection does not arrive at the macular part of a wearer is shown. From the graph shown in FIG. 4, it can be seen that the minimum curvature of the inner surface becomes smaller (the curve becomes slower) as the pupil diameter becomes smaller.

  Next, the method for determining the curvature of the inner surface of the spectacle lens in step S2 will be specifically described. In the following description, the first to fourth determination methods will be described. However, the designer may appropriately select which method is used.

<First determination method>
First, the first determination method will be described. In the first determination method, individual wearing conditions are determined for each wearer, and the curvature of the inner surface of the spectacle lens is determined by ray tracing simulation. In the above-described ray tracing simulation, wearing conditions that are widely applicable in general are set. However, depending on the wearer, there is a possibility that the wearing conditions are largely different from the set wearing conditions. Further, as can be seen from FIGS. 3 and 4, the minimum curvature of the inner surface changes by changing the wearing conditions (eyeball rotation angle, pupil diameter, etc.). Therefore, it is considered that the curvature of the inner surface can be determined more appropriately by determining individual wearing conditions for each wearer.

  In the first determination method, in step S1, the head shape of the wearer, the interpupillary distance, the pupil diameter, the axial length, the macular shape, the corneal apex distance, the eyeball rotation angle (maximum eyeball rotation angle or common eyeball rotation) Corner) and at least one of the frame shape of the glasses. In particular, the wearer's head shape, eye rotation angle (maximum eye rotation angle or regular eye rotation angle), pupil diameter, and eyeglass frame shape have a large effect on the minimum curvature of the inner surface. It is preferable to measure at least one or more. In step S1, these measurement results are determined as wearing conditions. Items that are not measured under wearing conditions are determined using general values such as statistical information.

  In step S2, the above-described ray tracing simulation is performed using the wearing conditions determined in step S1, and a minimum curvature that is a boundary that prevents the ray reflected from the inner surface of the spectacle lens from reaching the wearer's retina is obtained. It is determined as the curvature of the inner surface of the spectacle lens.

  In the ray tracing simulation described above, the light beam due to the internal reflection does not reach the wearer's retina regardless of the position of the light source at −90 ° ≦ α ≦ 90 ° or −90 ° ≦ β ≦ 90 °. The minimum curvature of the inner surface was determined. However, the wearer's spectacle lens usage environment is determined by hearing, etc., and based on the determined usage environment, the range of α and β, which is the position of the light source, is limited and a ray tracing simulation is performed to determine the minimum curvature of the inner surface. You may make it ask. For example, when the usage environment of the spectacle lens is limited to indoors, it is considered that light from a strong light source such as the sun enters through a window, so that the upper part of the wearer, for example α ≧ 0 and β ≧ You may make it limit the position of a light source to 0 range. In this way, by determining the curvature of the inner surface using the result of the ray tracing simulation in accordance with the actual usage situation of the spectacle lens, the inner surface curve is reduced while reducing the glare due to the inner surface reflection of the spectacle lens. As much as possible.

<Second determination method>
Next, the second determination method will be described. In the second determination method, a simulation is performed in advance using general statistical information as a wearing condition, and a relational expression indicating the relationship between the eyeball rotation angle and the curvature of the inner surface so that the light beam due to inner reflection does not reach the retina is obtained. Calculate it. When designing the spectacle lens, the curvature of the inner surface is determined using the eyeball rotation angle of the wearer and the relational expression.

For example, in the second determination method, the curvature of the inner surface is determined using the relationship between the eyeball rotation angle and the curvature of the inner surface as shown in FIG. The relationship between the curvature ρ2 of the inner surface and the eyeball rotation angle θ, which is indicated by the solid line L1 in the graph of FIG. 3 and does not reach the macular portion, is expressed by the following equation (8).
ρ2 ≧ a × θ ³ + b × θ ² + c × θ + d (8)
However,
a = 1.095 × 10 ⁻⁴
b = -2.388 × 10 ⁻²
c = 1.684
d = -2.333 × 10

Moreover, the relational expression between the curvature ρ2 of the inner surface and the eyeball rotation angle θ, which is indicated by a broken line L2 in the graph of FIG. 3 and does not reach the central fovea of the macula part, is expressed by the following equation (9). Is done.
ρ2 ≧ a × θ ³ + b × θ ² + c × θ + d (9)
However,
a = 5.482 × 10 ⁻⁴
b = -1.704 × 10 ⁻²
c = 1.659
d = −2.298 × 10

  When designing the spectacle lens, in step S1, the eyeball rotation angle (maximum eyeball rotation angle or regular eyeball rotation angle) of the wearer is measured and determined as the wearing condition.

  In step S2, the curvature ρ2 of the inner surface of the spectacle lens is determined so as to satisfy the relational expression (8) or (9) in which the eyeball rotation angle θ measured in step S1 is substituted.

  In the second determination method, when designing spectacle lenses individually, ray tracing simulation is not required, so that the curvature of the inner surface can be determined in a short time.

<Third determination method>
Next, the third determination method will be described. In the third determination method, the wearing condition of the wearer is uniformly determined from statistical information or the like to perform ray tracing simulation, and the curvature of the inner surface that prevents the light beam from the inner surface reflection from reaching the retina is set in advance as a statistical reference value. Make a decision. The third determination method is used when individual wear conditions for each wearer cannot be determined.

It is said that the maximum size of the visual field that can be gazes at the sum of the rotational movement of the human eyeball and the auxiliary movement of the head is about 40 to 50 degrees. With reference to this numerical value, for example, the maximum eyeball rotation angle is determined to be 50 degrees. According to the relationship between the minimum curvature of the inner surface and the eyeball rotation angle, which is indicated by the solid line L1 in the graph of FIG. 3 and does not reach the macular portion, the minimum curvature of the inner surface corresponding to the maximum eyeball rotation angle of 50 degrees. Is 1000/67. Based on this, when designing the spectacle lens, in step S2, the curvature of the inner surface is determined so that the curvature ρ2 of the inner surface satisfies the following expression (10).
ρ2 ≧ 1000/67 (10)

  In the third determination method, when the spectacle lens is individually designed, the measurement of the wearing condition of the wearer and the ray tracing simulation are not required, so that the curvature of the inner surface can be determined in a short time.

<Fourth determination method>
Next, the fourth determination method will be described. The wearer's wearing conditions vary depending on age and gender. For example, the head shape is different for adults and children, and is different for men and women. In addition, the pupil diameter tends to decrease as the age increases. Therefore, in the fourth determination method, the ray tracing simulation is performed by determining wearing conditions for each age and sex in advance. Then, the minimum curvature of the inner surface where the light beam from the inner surface reflection does not reach the retina is determined for each age and sex, and a correspondence table is created in which the age and sex are associated with the minimum curvature of the inner surface.

  When designing the spectacle lens, in step S2, the minimum curvature of the inner surface corresponding to the age and sex of the wearer is determined as the curvature of the inner surface of the spectacle lens using the correspondence table.

  In the fourth determination method, when the spectacle lens is individually designed, the measurement of the wearing condition of the wearer and the ray tracing simulation are not required, so that the curvature of the inner surface can be determined in a short time.

According to the embodiment described above, the following operational effects can be obtained.
In the spectacle lens design method, in step S2, after the inner surface has negative refractive power and the light beam from the light source at an arbitrary position behind the wearer is reflected by the inner surface based on the wearing condition of the wearer. Determine the curvature of the inner surface to avoid reaching the wearer's retina. In step S4, the curvature of the outer surface that satisfies the prescription conditions of the wearer is determined based on the curvature of the inner surface determined in step S2 and the refractive index of the optical material forming the spectacle lens. Thereby, the spectacle lens which reduced the glare by internal reflection can be designed.

(Modification 1)
When the prescription surface is an inner surface in a progressive-power lens or the like of individual orders, the shape of the inner surface may be changed by optimization design in accordance with prescription conditions. FIG. 5 is a flowchart for explaining the design procedure of the spectacle lens in this case. In steps S11 to S14 in FIG. 5, the same procedure as in steps S1 to S4 in FIG. 1 is performed. In step S15, the inner surface shape of the spectacle lens is optimized in accordance with the prescription conditions determined in step S13 using the curvature of the inner surface determined in step S12 as a limit value. That is, the inner surface shape of the spectacle lens is optimized so as not to be smaller than the curvature of the inner surface determined in step S12 (that is, the curve does not become slow). By doing this, even when the inner surface shape is optimized, a spectacle lens with reduced glare due to inner surface reflection can be generated as in the above-described embodiment.

(Modification 2)
In the above-described embodiment, an example in which the present invention is applied when designing a spectacle lens that reduces glare of internal reflection has been described. However, the present invention may be applied when selecting a spectacle lens that reduces glare of internal reflection.

  FIG. 6 is a flowchart for explaining a procedure for selecting a spectacle lens in the second modification. In steps S21 to S24 in FIG. 6, the same procedure as in steps S1 to S4 in FIG. 1 is performed. In step S25, a spectacle lens suitable for the wearer is selected from a plurality of spectacle lenses based on the curvature of the inner surface determined in step S22 and the curvature of the outer surface determined in step S24. For example, a spectacle lens whose inner surface has the curvature determined in step S22 and whose outer surface has the curvature determined in step S24 may be selected. Further, for example, among the plurality of spectacle lenses as options, a spectacle lens whose inner and outer curvatures are closest to the curvature determined in steps S22 and S24 may be selected.

(Modification 3)
In the above-described embodiment, an example in which a value obtained by averaging the average curvature at each curvature reference coordinate Pi on the inner surface is described as the curvature ρ2 of the inner surface of the spectacle lens. However, the value used as the curvature ρ2 of the inner surface of the spectacle lens is not limited to this, and may be a value based on the average curvature at each curvature reference coordinate Pi on the inner surface. For example, as the curvature ρ2 of the inner surface of the spectacle lens, the smallest value (that is, the curving value of the curve) of the average curvature at each curvature reference coordinate Pi on the inner surface may be used. In this way, the curvature ρ2 of the inner surface can be determined so as to prevent the inner surface reflection of the spectacle lens at any curvature reference coordinate Pi. Therefore, in the progressive addition lens having different average curvatures at each point of the spectacle lens, it is possible to prevent the internal reflection of the spectacle lens even at a portion where the average curvature is partially small (curve is gradual).

(Modification 4)
Even if it is unavoidable to reach the wearer's retina for every light beam reflected by the inner surface of the spectacle lens, it is worn after the light beam from the light source at an arbitrary position behind the wearer is reflected by the inner surface of the spectacle lens. In consideration of whether or not it reaches the retina of the person, the curvature ρ2 of the inner surface may be determined so as to reduce the rays that reach the retina of the wearer after being reflected by the inner surface of the spectacle lens. Even in this way, it is possible to reduce glare due to internal reflection of the spectacle lens.

(Modification 5)
In the embodiment described above, an example of determining the shape of the spectacle lens (the curvature ρ2 of the inner surface) in consideration of the light reaching the wearer's retina out of the light reflected by the spectacle lens and passing through the wearer's iris Explained. However, the shape of the spectacle lens (the curvature ρ2 of the inner surface) is determined in consideration of whether the light beam reflected by the spectacle lens reaches the retina and whether or not it passes through the iris of the wearer. You may do it. For example, the curvature ρ2 of the inner surface may be determined so as to reduce the light rays reflected by the inner surface of the spectacle lens and passing through the iris of the wearer. Even in this way, a spectacle lens that reduces glare due to internal reflection can be designed.

  In the second modification, an example in which the inner surface curvature ρ2 is determined in consideration of light rays reflected by the spectacle lens and reaching the retina of the wearer, and the spectacle lens is selected based on the determined inner surface curvature ρ2 will be described. did. However, the inner surface curvature ρ2 is determined in consideration of whether or not the light beam reflected by the spectacle lens reaches the retina, and whether or not it passes through the iris of the wearer, and the determined inner surface curvature is determined. The spectacle lens may be selected based on ρ2. Even in this case, it is possible to select a spectacle lens that reduces glare due to internal reflection.

  Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

10 ... head, 20 ... light source

Claims (14)

A spectacle lens design method for designing a spectacle lens having an outer surface that is a refractive surface on the object side in a worn state and an inner surface that is a refractive surface on the eyeball side in a worn state,
A spectacle lens design method, wherein a shape of the spectacle lens is determined in consideration of a light beam reflected by the spectacle lens and passing through an iris of a wearer. In the spectacle lens design method according to claim 1,
A spectacle lens design method, wherein a shape of the spectacle lens is determined in consideration of light rays that are reflected by the spectacle lens and pass through the iris of the wearer and reach the retina of the wearer. In the spectacle lens design method according to claim 2,
Arbitrary position behind the wearer based on at least one of head shape, interpupillary distance, pupil diameter, axial length, macular shape, corneal apex distance, eyeball rotation angle, and eyeglass frame shape A method for designing a spectacle lens, wherein the curvature of the inner surface is determined in consideration of whether or not a light beam from a light source in the lens reaches the retina of the wearer after being reflected by the inner surface of the spectacle lens. In the spectacle lens design method according to claim 3,
On the spectacle lens, at least one curvature reference coordinate is set,
The curvature of the inner surface is a value based on an average curvature at each curvature reference coordinate on the inner surface. In the spectacle lens design method according to claim 4,
The curvature of the inner surface is a value obtained by averaging the average curvature at each curvature reference coordinate on the inner surface. In the spectacle lens design method according to claim 4,
The curvature of the inner surface is the smallest value among the average curvatures at the respective curvature reference coordinates on the inner surface. In the spectacle lens design method according to any one of claims 4 to 6,
The spectacle lens, wherein the curvature reference coordinate is at least one of a geometric center coordinate of the spectacle lens, a standard coordinate for measuring the power of the spectacle lens, a distance reference point, and a near reference point. Design method. In the spectacle lens design method according to any one of claims 3 to 7,
The spectacle lens design method, wherein the curvature ρ2 of the inner surface is determined so as to satisfy the following expression (1).
ρ2 ≧ 1000/67 (1) In the spectacle lens design method according to any one of claims 3 to 7,
A spectacle lens design method, wherein the curvature ρ2 of the inner surface is determined so that the following equation (2) is satisfied, where θ is the eyeball line angle of the wearer.
ρ2 ≧ a × θ ³ + b × θ ² + c × θ + d (2)
However,
a = 1.095 × 10 ⁻⁴
b = -2.388 × 10 ⁻²
c = 1.684
d = -2.333 × 10 In the spectacle lens design method according to any one of claims 3 to 7,
A spectacle lens design method, wherein the curvature ρ2 of the inner surface is determined so that the following equation (3) is satisfied, where θ is the eyeball line angle of the wearer.
ρ2 ≧ a × θ ³ + b × θ ² + c × θ + d (3)
However,
a = 5.482 × 10 ⁻⁴
b = -1.704 × 10 ⁻²
c = 1.659
d = −2.298 × 10 In the spectacle lens design method according to any one of claims 3 to 7,
A spectacle lens design method comprising: measuring at least one of a wearer's head shape, eyeball line angle, pupil diameter, and spectacle frame shape, and using the measurement result when determining the curvature of the inner surface . In the spectacle lens design method according to any one of claims 3 to 11,
5. A spectacle lens design method, comprising: optimizing the shape of the inner surface by using the determined curvature of the inner surface as a limiting value.   The spectacle lens manufacturing method characterized by manufacturing the spectacle lens designed by the spectacle lens design method as described in any one of Claims 1-12. A spectacle lens selection method for selecting a spectacle lens having an outer surface that is a refractive surface on the object side in a wearing state and an inner surface that is a refractive surface on the eyeball side in a worn state,
A spectacle lens selection method comprising: selecting the spectacle lens in consideration of a light beam reflected by the spectacle lens and passing through an iris of a wearer.

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