JP6374345B2 - Vision correction lens design method and vision correction lens - Google Patents

Description

  The present invention relates to a vision correction lens such as a spectacle lens or a contact lens and a design method thereof, and more particularly to a vision correction lens having a depth of focus extension effect and a design method thereof.

  Patent Document 1 below describes an optical plate of a second optical system that is disposed in front of a first optical system that is an imaging optical system for incident light waves and that can extend the depth of focus. . The optical plate is assumed to increase in thickness approximately in proportion to a third-order power function of the distance from the base point in the optical plate.

JP 2009-282391 A (refer to claims 1 and 2)

  By the way, those who have diminished eye accommodation due to aging or fatigue are less likely to feel contrast in dark places with low illuminance, such as in the evening or at night. There was a problem.

  The present invention solves the above-described problems, and an object of the present invention is to provide a vision correction lens design method and a vision correction lens capable of improving contrast sensitivity in a dark place.

The eyeglass lens design method for correcting vision according to the present invention is determined based on the prescription power when the longitudinal axis passing through the geometric center of the lens is the z axis and the backward direction of the lens is the positive direction of the z axis. A spectacle lens for correcting vision that adds a depth-of-focus component represented by Ar ³ (where r is a distance from the z-axis and A is a constant) to the z-coordinate value of the refracting surface to extend the depth of focus. Wherein the constant A is such that the absolute value of the constant A falls within the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ when the unit of r is mm. And the depth of focus extension component is added to the front surface of the lens with the constant A being positive, or the depth of focus extension component is added to the rear surface of the lens with the constant A being negative . According to the eyeglass lens for correcting vision produced by this creation method, the depth of focus that becomes shorter (shallow) is extended in the dark, and it becomes easier to focus on an object in front of or behind the original focus. The contrast sensitivity in the dark can be improved. In addition, if the absolute value of the constant A is within a range in a normal-sized spectacle lens, an effect of extending the depth of focus can be appropriately obtained, and the occurrence of astigmatism can be suppressed.

The eyeglass lens for correcting vision according to the present invention has a refraction determined based on the prescription power when the longitudinal axis passing through the geometric center of the lens is the z-axis and the backward direction of the lens is the positive direction of the z-axis. A vision correction spectacle lens in which a depth-of-focus component represented by Ar3 (where r is a distance from the z-axis and A is a constant) is added to the z-coordinate value of the surface to extend the depth of focus. , the unit of r is taken as mm, Ri absolute value near the range of 1.73 × 10-6~1.96 × 10-5 of the constant a, the constant a positive and has been the lens The depth of focus extension component is added to the front surface, or the constant A is negative and the depth of focus extension component is added to the rear surface of the lens . According to this, the depth of focus, which becomes shorter (shallow) in the dark place, is extended, and it becomes easier to focus on the object in front of or behind the original focus. Therefore, the contrast sensitivity in the dark place can be improved. is there. In addition, if the absolute value of the constant A is within a range in a normal-sized spectacle lens, an effect of extending the depth of focus can be appropriately obtained, and the occurrence of astigmatism can be suppressed.

(A) is the schematic of the whole lens which concerns on 1st Embodiment, (b) is the schematic which expanded the upper half of the lens. It is a figure for demonstrating the lens which concerns on 1st Embodiment. (A) is a schematic diagram of the focusing state of the light beam by the normal single focus lens, (b) is a schematic diagram of the focusing state of the light beam by the lens according to the first embodiment. (A) Depth of focus of normal single focus lens in bright place, (b) Depth of focus of normal single focus lens in dark place, (c) Depth of focus of lens according to first embodiment in dark place It is a figure for demonstrating. It is a figure which shows the photograph which image | photographed the target in the bright place using the normal single focus lens. It is a figure which shows the photograph which image | photographed the optotype in the bright place using the lens which concerns on 1st Embodiment. It is a figure which shows the photograph which image | photographed the target in the dark place using the normal single focus lens. It is a figure which shows the photograph which image | photographed the optotype in the dark place using the lens which concerns on 1st Embodiment. (A) is the schematic of the whole lens which concerns on 3rd Embodiment, (b) is the schematic which expanded the upper half of the lens. (A) is a state in which the constant A is positive and a depth-of-focus extension component is added to the rear surface of the lens. (B) is a state in which the constant A is negative and a depth-of-focus extension component is added to the front surface of the lens. ) Is a state in which constant A is negative and a depth of focus extension component is added to the rear surface of the lens, and (d) is a schematic diagram showing a state in which constant A is positive and a depth of focus extension component is added to the front of the lens. is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, front and rear, left and right, and top and bottom for a wearer wearing spectacles using a lens are front and rear, left and right, and top and bottom, respectively, of the lens.

<First Embodiment> As shown in FIG. 1, a lens 1 according to a first embodiment is a vision correction lens for correcting the visual acuity of a wearer, and specifically, a spectacle lens used for spectacles. It is. In the lens 1, the rear surface 2 is a concave surface defined by the equation (i), and the front surface 3 is a convex surface defined by the equation (ii). The longitudinal axis passing through the geometric center of the lens 1 (base point O _{1 on} the rear surface 2 and base point O _{2 on the} front surface 3) is defined as the z axis, and the direction toward the rear of the lens 1 is defined as the positive direction of the z axis. The z axis coincides with the optical axis of the lens 1.

_{^{z = r 2 / (R 1}} + (R 1 2 -Kr 2) 1/2) + Ar 3 ... (i)
z = r ² / (R ₂ + (R ₂ ² −Kr ² ) ^1/2 ) (ii)

In the expressions (i) and (ii), r is a distance from the z axis. That is, when considering an orthogonal coordinate system centered on the base point O _{1 on} the rear surface 2 and the base point O ₂ on the front surface 3 and having the vertical and horizontal axes orthogonal to the z axis as the x axis and the y axis, respectively, r = (X ² + y ² ) ^1/2 . R ₁ and R ₂ are radii of curvature at the vertices of the surface, K is 1, and A is a positive constant. Therefore, the front surface 3 of the lens 1 is spherical and the rear surface 2 is aspheric. Note that R ₁ and R ₂ are determined by the prescription power (specifically, the S power, the C power, and the astigmatic axis AX). Since the lens 1 is a distance lens for a nearsighted person, R ₁ <R ₂ .

As shown in the equation (i), the rear surface 2 has a third-order term Ar ³ of r added to the z coordinate value of the refractive surface defined by the following equation (iii) based on the prescription power.
z = r ² / (R ₁ + (R ₁ ² −Kr ² ) ^1/2 ) (iii)

The term Ar ³ is a depth-of-focus extension component added to increase the depth of focus. It is described in Patent Document 1 that the depth of focus can be extended by passing light through an optical plate whose thickness is changed in proportion to a cubic power function of the distance r from the base point. The lens 1 is an application of this, and is a refracting surface determined in accordance with the prescription power (in the embodiment, a spherical surface having a radius of curvature R _1. Hereinafter, it is also referred to as an original spherical surface, and a symbol S in FIG. In the rear surface 2 (that is, the distance from the base point O ₁ that is the intersection of the z axis and the rear surface 2 shown in FIG. The rear surface 2 is formed by adding a portion where the thickness changes (focus depth extension component). From the above formulas (i) and (iii), it can be said that the rear surface 2 is a composite of a spherical surface having a radius of curvature R _{1 and} an aspherical surface represented by Ar ^{3. In} other words, the rear surface 2 is shown in FIG. As schematically shown, a power component for realizing the prescription power and a focal depth extension component (aspherical component) for extending the focal depth are synthesized and formed.

The constant A is selected from the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ . This is because when the constant A is within this range in a normal-sized spectacle lens (diameter 50 to 80 mm), the effect of extending the depth of focus can be appropriately obtained, and the occurrence of astigmatism can be suppressed. That is, the greater the constant A, the greater the depth of focus effect, but the greater the occurrence of astigmatism. The range in consideration of the balance is the above range.

In the present embodiment, A = 7.68 × 10 ⁻⁶ . As shown in FIG. 1B, when Δ is the height in the z-axis direction at the radius a with respect to the original spherical surface S (that is, the increase in thickness from the original spherical surface S). When a is 25 mm, Δ is a value of 120 μm. Note that A = Δ / 1000 / a ³ holds (where a is a unit: mm and Δ is a unit: μm). Incidentally, when a is 25 mm and Δ is 27 μm, A = 1.73 × 10 ⁻⁶ , and when a is 15 mm and Δ is 66 μm, A = 1.96 × 10 ⁻⁵ .

  Next, a method for designing the lens 1 will be described.

First, the refractive surface of the front surface 3 and the refractive surface of the rear surface 2 of the lens 1 are determined based on the prescription power. This determination method is well known and will not be described in detail here. Then, the determined depth coordinate component represented by Ar ³ (where r is the distance from the z-axis and A is a constant) is added to the determined z-coordinate value of the refractive surface of the front surface 3 and the refractive surface of the rear surface 2. Append.

In the embodiment, the refractive surface of the front surface 3 and the refractive surface of the rear surface 2 of the lens 1 are determined as spherical surfaces represented by the above formulas (ii) and (iii) based on the prescription power, respectively, and the refractive surface of the rear surface 2 is determined. The depth-of-focus component Ar ³ (where A = 7.68 × 10 ⁻⁶ ) was added to the z coordinate value.

  Next, the effect of extending the focal depth will be described.

FIG. 3A is a schematic diagram of a focused state of the light beam 22 by the normal lens 10 in which the front and rear refracting surfaces are determined based on the prescription power, and the light beam parallel to the optical axis incident on the lens 10. 22, since the gather intensively at the focal point P _3, the focal position P _3, the signal strength seen high clearly objects, for example, in slightly offset positions focus as the position P _4, rapidly blurring Disappear. That is, the depth of focus (in other words, the depth of field) is shallow. The set of points shown in the lower part of the figure schematically represents how the light beam 22 is focused at the positions P ₁ , P ₂ , P ₃ , P ₄ and P ₅ .

(B) in FIG. 3 is a schematic diagram of a focused state of the light beam 22 by the lens 1, the light beam 22 parallel to the optical axis which enters the lens 1 is gathered and dispersed in a certain range including the focal position P ₃ , The depth of focus becomes deeper. Therefore, although some blur remains at the focal position P ₃ , the object can be identified even at a position slightly defocused, such as the position P ₄ , because the signal intensity at the center is high to some extent. When the constant A is a positive number, the focal depth is extended to the rear side (back side) of the original focal position P ₃ .

The effect of extending the depth of focus is great especially in dark places where illumination is low, such as at night. Hereinafter, a description will be given with reference to FIG. FIG. 4 shows the state of the eyeball 20 including the iris 21. Note that symbols F ₁ , F ₂ , and F ₃ in FIG. 4 represent the depth (length) of the focal depth.

FIG. 4 (a) shows a state in a bright place with high illuminance such as daytime. Since the iris 21 is closed and the incident light beam 22 becomes thin, the range in which the light is concentrated becomes long, and the focus is increased. The depth F ₁ becomes deep (long). Therefore, it is focused at a relatively long distance.

FIG. 4B shows a state in a dark place. Since the iris 21 is opened and the incident light beam 22 is thickened, the light concentration range is shortened, and the focal depth F ₂ is shallow. (Short). Therefore, the in-focus distance is shortened.

FIG. 4C shows a state in which the lens 1 is used in a dark place. The iris 21 is opened and the incident light beam 22 becomes thick, but the focal depth F ₃ is deep, so that it is relatively long. Focus on distance. Therefore, according to the lens 1, it becomes easy to identify an object particularly in a dark place.

  FIGS. 5 to 8 show a case where a normal single focus lens (not including a degree) to which a depth-of-focus extension component is added is attached to the front side of the camera lens, and the single focus lens. The result of an experiment in which a target was photographed and the depth of field was compared, respectively, when a depth of focus extension lens with a depth of focus extension component added to a single focus lens of the same design as above was attached. . Detailed data of the lenses used in this experiment are shown in Tables 1 and 2. The sag value (z coordinate value) shown in Table 1 is a value at a distance r = 35 mm from the center (that is, the edge of the lens). A plurality of visual targets were arranged obliquely with respect to the camera at equal intervals (the interval in the front-rear direction was 15 cm in FIGS. 5 and 6 and 10 cm in FIGS. 7 and 8).

  FIG. 5 is a single focus lens, and FIG. 6 is a photograph using a depth-of-focus extension lens, all of which are taken in a bright place. The focal length is 135 mm, the F value is 4.5, the shutter speed is 1/25, ISO 400, and the most from the camera. The distance to the front target is about 200 cm, the illuminance is 80 lx near the camera, and 90 lx near the front target.

  FIG. 7 shows a single focus lens, and FIG. 8 shows a depth of focus extension lens, both of which were taken in a dark place. Focal length 135 mm, F value 8.0, shutter speed 1/10, ISO 400, most from camera The distance to the front target is about 100 cm, and the illuminance is 48 lx near the camera, and 55 lx near the front target.

  5 and FIG. 6 and FIG. 7 and FIG. 8 show that the view in FIG. 6 and FIG. 8 using the depth-of-focus extension lens is deeper than that in FIG. 5 and FIG. 7 using the normal single focus lens. It can be seen that the depth of field is deeper, and that the difference in depth of field between the two lenses is greater in the dark place than in the bright place.

Next, for 7 subjects, the front surface is determined by the above formula (ii) according to the prescription frequency and the rear surface is determined by the above formula (iii), and the depth of focus extension component Ar ³ (provided on the rear surface) , A = 7.68 × 10 ⁻⁶ ) to which a depth-of-focus extension lens, that is, the lens 1 is prepared, and is used by the subject to measure the contrast sensitivity will be described. Table 3 shows the age of each subject, the prescription power, and the power of the created lens. Since the created lens is a prototype, there is a slight difference between the prescription power and the lens power. In Table 3, R is the right eye, L is the left eye, and the refractive index of the lens is 1.60. The contrast sensitivity was measured using a Vitech vision contrast tester 6500.

Table 4 shows the measurement results. Vitech's vision contrast tester 6500 has a plurality of targets arranged for each of the targets A to E, and measures contrast sensitivity according to which target can be identified. The test subject indicates to which target the target A to E can be identified. In Table 4, lens A represents a normal single focus lens, and lens B represents lens 1. For each subject, the right eye, left eye, and both eyes were measured, and the measurement was performed in a bright place and a dark place. Table 4 describes the illuminance at the measurement location. The distance from the subject to the target is 3.00 m in all cases.

  For example, if the measurement result is “6” for the target B, the contrast sensitivity is “85”, and if the measurement result is “7”, the contrast sensitivity is “170”. . Table 5 is based on the contrast sensitivity obtained from the measurement results in Table 4, when using a normal single focus lens in each of the light place and dark place for each subject's right eye, left eye, and both eyes. The ratio of the contrast sensitivity when the lens 1 is used to the contrast sensitivity, that is, (contrast sensitivity when using the lens 1) / (contrast sensitivity when using a normal single focus lens) E is obtained and the average through the target is calculated.

  From Table 5, for example, when the subject A is binocular in a bright place, the contrast sensitivity when the lens 1 is used is 100% when the normal single focus lens is used. The contrast sensitivity does not change even when a single focal lens is used. However, when binocular viewing is performed in a dark place, the contrast sensitivity when the lens 1 is used is 220% when the normal single focal lens is used. When 1 is used, the contrast sensitivity is more than twice as high as when a normal single focus lens is used. Thus, in a dark place (illuminance of 50 lx or less), improvement in contrast sensitivity was observed for 12 of 16 eyes. That is, according to the lens 1, the contrast sensitivity is improved in the dark where the contrast is low, such as in the evening or at night, and the effect of improving the contrast sensitivity in the dark is particularly high in middle-aged and elderly people whose contrast sensitivity is drastically decreased. I understand.

Further, if the constant A is selected from the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ , the effect of extending the depth of focus can be appropriately obtained, and the generation of astigmatism can be suppressed. That is, since the depth of focus is extended while the peripheral distortion is suppressed, the eye adjustment is assisted, and the eye feels comfortable and is not easily fatigued.

  <Second Embodiment> Next, a second embodiment will be described. Components that are the same as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The lens according to the second embodiment is also a spectacle lens, and the front surface 3 is a convex surface defined by the above formula (ii) like the lens 1, but the lens edge thickness is reduced to the z coordinate value of the rear surface 2. For this purpose, an edge thickness reduction component Dr ¹⁰ (where D is a negative constant) is added. That is, the rear surface 2 of the lens of the second embodiment is a concave surface defined by the following equation (iv).

z = r ² / (R ₁ + (R ₁ ² −Kr ² ) ^1/2 ) + Ar ³ + Dr ¹⁰ (iv)
In the lens of the second embodiment, the edge thickness reduction component Dr ¹⁰ is added because the addition of the depth of focus extension component Ar ³ (where A is a positive constant) increases the lens edge thickness. This is because there is a possibility that a problem may occur in terms of weight, and this possibility is reduced. The reason why the index of r in the edge thickness reduction component is increased to 10 is to reduce the edge thickness by increasing the influence at the edge of the lens. In the central part of the surface 2 after being used for viewing an object and r is small, it is assumed edge thickness reduction component Dr ¹⁰ is small, it does not negatively impact on the focal depth extension effect.

As described in the first embodiment, the constant A is preferably selected from a range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ , but when the constant A is selected from such a range, the constant A is selected. D is preferably selected from the range of −1.88 × 10 ⁻¹⁶ to −1.65 × 10 ⁻¹⁷ , and the constant D is preferably selected such that the absolute value of the constant D increases as the constant A increases. This is because the lens edge thickness is equivalent to that of a normal single focus lens.

The range of the constant D is an increase in the edge thickness of the lens 1 of the first embodiment when the constant A is within the above range as compared with a normal single focus lens (75 mm often used for spectacle lenses). (Increased edge thickness when using a lens with a diameter) was calculated, and the increase was calculated as D = Δ / a ¹⁰ (where a = 37.5 mm, unit of Δ: mm).

Table 6 shows that A = 1.73 × 10 ⁻⁶ and D = −1.65 × 10 ^−17, and Table 7 shows that A = 1.96 × 10 ⁻⁵ and D = −1.88 ×. 10 ^-16 and then the lens 1 of the first embodiment when the those lenses in the second embodiment, and the edge thickness of the conventional single-focus lens (both the lens diameter is 75 mm), was calculated by changing the S power Indicates.

As can be seen from Tables 6 and 7, by adding the edge thickness reduction components Dr ^10, the lens of the second embodiment edge thickness becomes equal to the normal single-focus lens.

  According to the lens of the second embodiment, like the lens 1, the contrast sensitivity in a dark place is improved, and in particular, the contrast sensitivity is improved in a dark place for middle-aged and elderly people, and the edge thickness of the lens is reduced to a normal lens. Can be equivalent.

  <Third Embodiment> The first embodiment and the second embodiment are single focus lenses (distance lenses) for nearsighted persons, but the third embodiment is a single focus lens (near distance lenses) for farsighted persons. ). Hereinafter, the third embodiment will be described, but the same reference numerals are given to the components common to the components of the first embodiment, and the description thereof will be omitted as appropriate.

Also in the lens of the third embodiment, the rear surface 2 is defined by the above equation (i), the front surface 3 is defined by the above equation (ii), and the depth of focus extension component Ar ³ is added to the concave surface (rear surface 2) of the lens. The constant A is a negative number and is selected from a range of −1.96 × 10 ⁻⁵ to −1.73 × 10 ⁻⁶ . This is because, in a normal size eyeglass lens, within this range, a depth-of-focus extension effect can be appropriately obtained, and the occurrence of astigmatism can be suppressed. Further, R ₁ > R ₂ is satisfied.

  FIG. 9 shows a schematic diagram (a) of the whole lens of the third embodiment and a schematic diagram (b) in which the upper half is enlarged. As shown in FIG. 9B, in the case of the lens according to the third embodiment, the thickness is reduced from the original spherical surface S indicated by the two-dot chain line, and the amount of decrease in the thickness becomes larger as the lens is closer to the edge of the lens. .

Table 8 shows an example of the lens of the third embodiment when the S frequency is + 1.00D, + 2.00D, and + 3.00D. The constant A was set to −7.68 × 10 ⁻⁶ .

  As in the third embodiment, by setting the constant A to a negative number, the focal depth is extended to the front side of the focal point before the focal depth extension. Since the edge thickness of the lens is thinner than before the depth of focus extension, it is not necessary to add an edge thickness reduction component.

According to the lens of the third embodiment, since the height from the original spherical surface S decreases in proportion to the cubic power function of the distance r from the base point O ₁ , the focal point becomes closer to the lens edge. Sneak away. Accordingly, the extended depth is extended, and the contrast sensitivity in the dark is improved. In addition, it is not necessary to add an edge thickness reduction component.

  <Fourth Embodiment> The fourth embodiment is a single focus lens (near lens) for a far-sighted person, but unlike the third embodiment, the constant A is a positive number. Hereinafter, although the fourth embodiment will be described, the same reference numerals are given to the components common to the components of the first embodiment, and the description thereof will be omitted as appropriate.

In the lens of the fourth embodiment, the rear surface 2 is defined by the above equation (i), the front surface 3 is defined by the above equation (ii), and the depth of focus extension component Ar ³ is added to the concave surface (rear surface 2) of the lens. The constant A is a positive number, and is selected from the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ . This is because a normal depth spectacle lens is within this range, the effect of extending the depth of focus can be appropriately obtained, and the occurrence of astigmatism can be suppressed. Further, R ₁ > R ₂ is satisfied. When the constant A is a positive number, the focal depth is extended to the rear side of the focal point before the focal depth extension.

Table 9 shows an example of the lens of the fourth embodiment when the S frequency is + 1.00D, + 2.00D, and + 3.00D. The constant A was 7.68 × 10 ⁻⁶ .

When the constant A is a positive number, the focal depth is extended to the rear side of the focal point before the focal depth extension. Further, since the edge thickness is increased, the edge thickness reducing component Dr ¹⁰ may be added. When the constant A is selected from the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ , the constant D is in the range of −1.88 × 10 ⁻¹⁶ to −1.65 × 10 ⁻¹⁷ . It is preferable that the absolute value of the constant D increases as the constant A increases.

According to the lens of the fourth embodiment, the height from the original spherical surface S increases in proportion to the cubic power function of the distance r from the base point O _1. Sneak away. Accordingly, the extended depth is extended, and the contrast sensitivity in the dark is improved.

  <Modification> A modification will be described below.

  (1) The constant A may be a negative number in a distance lens such as the lens of the first embodiment. When the constant A is a negative number, the depth of focus is extended to the front side of the focus when the depth of focus extension component is not added. Also, the edge thickness is smaller than when no depth-of-focus extension component is added.

(2) The expression of the refracting surface before adding the depth-of-focus extension component Ar ³ is not limited to the above expression (ii), and for example, a polynomial represented by ΣA _i r ⁱ is added to the above expression (ii). (That is, the refracting surface before adding the depth of focus extension component Ar ³ is not necessarily a spherical surface). In that case, a depth-of-focus extension component Ar ³ is added to the equation. Of course, the formula of the surface to which the depth-of-focus extension component is not added (the front surface 3 in the above embodiments) is not limited to the above formula (iii).

  (3) In each of the above embodiments, the depth of focus extension component is added to the rear surface 2 (concave surface), but the depth of focus extension component may be added to the front surface 3 (convex surface) of the lens.

That is, the focal depth extension component may be added to the rear surface 2 and may be added to the front surface 3. In each case, the constant A may be positive or negative. FIG. 10 shows these four cases, and FIG. 10A shows a depth-of-focus extension component on the rear surface 2 with a constant A as a positive number, as in the first and fourth embodiments. The added state, (b) is a state in which the constant A is a negative number, and a depth-of-focus extension component is added to the front surface 3, and (c) is the rear surface in which the constant A is a negative number as in the third embodiment. 2 shows a state in which the depth of focus extension component is added, and (d) shows a state in which the constant A is a positive number and the depth of focus extension component is added to the front surface 3. In the figure, the alternate long and two short dashes line indicates the surface before addition of the depth of focus extension component. The constant A preferably has an absolute value in the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ . This is because, within such a range, it can be understood from the calculation that the effect of extending the depth of focus can be obtained moderately and the generation of astigmatism can be suppressed.

In the cases (a) and (b), the edge thickness increases, and therefore an edge thickness reduction component may be added. In the cases of (c) and (d), the edge thickness is reduced, so that it is not necessary to add an edge thickness reduction component. When adding an edge thickness reduction component, when constant A is a positive number as in (a), constant D is a negative number, and when constant A is a negative number as in (b) The constant D is a positive number. When the absolute value of the constant A is in the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ , the absolute value of the constant D is 1.65 × 10 ^{−17 to} 1.88 × 10 ^−16. It is preferable that the absolute value of the constant D increases as the absolute value of the constant A increases. If the constant A and the constant D are determined in this way for a spectacle lens of a normal size, the effect of extending the depth of focus can be obtained moderately, astigmatism can be suppressed, and the edge thickness can be reduced as the depth of focus component. This is because it can be understood from the calculation that the lens can be equivalent to the lens before the addition.

(4) The index of r in the edge thickness reduction component does not have to be 10. For example, 8 may be used, and Dr ⁸ may be added as the edge thickness reduction component.

  (5) Although the above embodiments are single focus lenses, a depth of focus extension component may be added to a multifocal lens such as a progressive lens or a bifocal lens. This is because the depth of focus extension effect can be obtained as in the case of the single focus lens. In that case, the concave surface is a progressive power surface or a multifocal surface, and a depth of focus extension component is added to the convex surface, or the convex surface is a progressive power surface or a multifocal surface, and a depth of focus extension component is added to the concave surface, etc. The depth of focus extension component may be added to the progressive power surface or the multifocal surface, or may be added to the opposite surface.

  (6) When adding a depth of focus extension component to a progressive lens or bifocal lens, the whole including a distance portion (distance refracting surface) and a near portion (near refracting surface) (in the case of a progressive lens, May be added to each of the distance portion, the near portion, and the progressive portion, or may be added separately to each of the distance portion and the near portion, or only the distance portion or only the near portion May be added. When the distance portion and the near portion are separately added, the constant A may be different between the distance portion and the near portion. The same applies when there are more than two focal points.

  (7) In the case of a progressive lens or a multifocal lens, the S frequency of the prescription power of the distance portion is designed to be + 0.25D (that is, the distance portion is made 0.25D weaker), and the focal point is focused on the distance portion. By adding a depth extension component to compensate for the difficulty of seeing when the degree is weakened, the addition is reduced by 0.25D, and accordingly, the occurrence of distortion or the like is suppressed.

  (8) The present invention may be applied to contact lenses.

1 ... Lens 2 ... Rear 3 ... Front

Claims (3)

Depth of focus is extended to the z coordinate value of the refracting surface determined based on the prescription power when the longitudinal axis passing through the geometric center of the lens is the z axis and the backward direction of the lens is the positive direction of the z axis. Therefore, a design method of a spectacle lens for correcting vision, which adds a depth of focus extension component represented by Ar ³ (where r is a distance from the z-axis and A is a constant),
The constant A is set so that the absolute value of the constant A is in the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ when the unit of r is mm.
A vision correction spectacle lens characterized in that the constant A is positive and the depth of focus extension component is added to the front surface of the lens, or the constant A is negative and the depth of focus extension component is added to the rear surface of the lens. Design method. Depth of focus is extended to the z coordinate value of the refracting surface determined based on the prescription power when the longitudinal axis passing through the geometric center of the lens is the z axis and the backward direction of the lens is the positive direction of the z axis. Therefore, a design method of a spectacle lens for correcting vision, which adds a depth of focus extension component represented by Ar ³ (where r is a distance from the z-axis and A is a constant),
The constant A is set so that the absolute value of the constant A is in the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ when the unit of r is mm.
The eyeglass lens for correcting vision is a progressive lens or a bifocal lens provided with a refractive surface for distance and a refractive surface for near use on the refractive surface,
The distance refracting surface is designed by adding + 0.25D to the S power of the prescription power of the distance refracting surface, and the focal depth extension component is added to the z coordinate value of the distance refracting surface. A design method for eyeglass lenses for correcting vision. Depth of focus is extended to the z coordinate value of the refracting surface determined based on the prescription power when the longitudinal axis passing through the geometric center of the lens is the z axis and the backward direction of the lens is the positive direction of the z axis. Therefore, a depth of focus extension component represented by Ar ³ (where r is a distance from the z-axis and A is a constant) is added,
When the unit of r is mm, the absolute value of the constant A is in the range of 1.73 × 10 ^{−6 to} 1.96 × 10 ⁻⁵ ,
The constant A is positive and the depth of focus extension component is added to the front surface of the lens, or the constant A is negative and the depth of focus extension component is added to the rear surface of the lens. Eyeglass lenses for correcting vision.