JP2019105823A - Method for designing lens for eyeglasses and lens for glasses - Google Patents

Abstract

To provide a method for designing a lens for eyeglasses where a front lens surface is set with a radius of curvature of 150 mm or less, and with which it is possible to obtain a greater depth of field extension effect in a region close to lens periphery than possible before.SOLUTION: A combination is made from an average power stabilization component, expressed by Br+Cr+Dr+Er(where, r is the distance from an axis z, and B, C, D, E are constants), the axis z representing an axis in the longitudinal direction passing through the optical center of a lens, which suppresses a change of average power in a lens plane, a depth of field extension component expressed by Ar(where, A is a constant), which extends the depth of field, and further a camber angle correction component, expressed on a plurality of divided lines radially extending from the optical center by F(θ)r+G(θ)r+H(θ)r+I(θ)r(where, F(θ), G(θ), H(θ), I(θ) are constants, θ is an angle from an axis x orthogonal to the axis z), which works so as to cancel out a change of average power that occurs when the optical axis of the lens is titled at a prescribed camber angle, the combination being added to the z coordinate value of rear surface 2 of the lens that is determined on the basis of prescribed power.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an eyeglass lens having a depth-of-field extension effect, and more particularly, to an eyeglass lens in which the front surface of the lens is set to have a curvature radius of 150 mm or less and a design method thereof.

In the following Patent Document 1, assuming that the axis in the front-rear direction passing through the lens center is the z axis and the direction toward the rear of the lens is the positive direction of the z axis, , A vision correction lens to which the focal depth extension component represented by Ar ³ is added. As described above, the lens to which the focal depth (field depth) extension component is added expands the range viewed in focus, and therefore an image with less blur can be obtained in a wide range. In addition, in the spectacles wearer, the operation of focusing using the adjustment power of the eye is reduced, and the adjustment fatigue is reduced. A lens to which such a focal depth (depth of field) extension component is added facilitates visual recognition of a moving object, and thus can be particularly suitably used as a sports lens.

JP, 2016-206338, A

By the way, in recent years, a high curve lens in which the front surface of the lens is a deep curve has been provided. Such a high curve lens can improve the visual field and reduce the entry of foreign matter and wind by being worn along the face, and is often used as a sports lens in particular.
By adding the above-described depth of field extension function to such a high curve lens, it is possible to further enhance the added value as a sport lens.
However, even if the above-mentioned depth-of-field extension component represented by Ar ³ is simply added to a lens whose front surface is a deep curve, the depth-of-field extension effect decreases toward the lens periphery. there were.

  The present invention solves such a problem, and it is an eyeglass whose lens front surface has a radius of curvature of 150 mm or less, which can obtain an effect of extending the depth of field more than conventional in a region near the lens periphery. It is an object of the present invention to provide a lens design method and an eyeglass lens.

The present invention is a method of designing a lens for spectacles, wherein the front surface of the lens is set to have a radius of curvature of 150 mm or less,
Assuming that the longitudinal axis passing through the optical center of the lens is the z axis and the direction toward the rear of the lens is the positive direction of the z axis, the z coordinate value of the rear surface of the lens determined based on the prescribed power is Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ (where r is the distance from the z axis, B, C, D and E are constants), and an average power stabilization component is added to suppress fluctuations in the average power in the lens surface. 1 aspheric component addition step,
A second aspheric component addition step of adding a depth-of-field extension component represented by Ar ³ (where A is a constant) and extending the depth of field to the z-coordinate value of the rear surface of the lens; It is characterized by having.

The effect of the depth of field extension can be obtained by changing the power in the lens surface from the optical center toward the lens peripheral edge. However, the aspheric surface component represented by Ar ³ (A is a positive number) changes the in-lens power in the negative direction from the optical center to the lens peripheral edge, but has a curvature radius of 150 mm or less on the front surface. In a lens in which a deep curve is set, the dioptric power changes toward the lens peripheral edge toward the lens peripheral edge, so a part of the depth-of-field extension effect by the aspheric surface component represented by Ar ³ is canceled out. The effect of extending the depth of field in the near area has become smaller.

Therefore, in the present invention, the average dioptric power stabilizing component represented by Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ is first added to correct the average dioptric power in each part in the lens surface to be substantially constant, and then Ar ³ The depth of field extension component represented by is added. According to the design method of the present invention, it is possible to suppress the reduction in the depth of field extension effect in the area close to the lens periphery and extend the depth of field by a certain amount or more even when visualizing through the area close to the lens periphery It is possible to provide an eyeglass lens in which the lens front surface is set to have a curvature radius of 150 mm or less, which can obtain an effect.

Further, in the design method of the present invention, F (θ) r ⁴ + G (θ) r ⁶ + H (θ) r ⁸ + I (θ) r is obtained on a plurality of dividing lines set so as to extend radially from the optical center of the lens. ¹⁰ (where F (θ), G (θ), H (θ), I (θ) are constants and θ is an angle from the x-axis orthogonal to the z-axis), and A third aspheric surface that adds to the z-coordinate value of the rear surface of the lens a warp angle correction component that works to cancel the change in average power that occurs when the optical axis of the lens is tilted at a predetermined warp angle with respect to the sight line. A component addition step can further be provided.
In this way, J (θ) r ³ + K (θ) r ⁴ + L (θ) r ^{6 formed} by combining the respective aspheric surface components obtained in the first, second and third aspheric surface component addition steps. + M (θ) r ⁸ + N (θ) r ¹⁰ (where J (θ), K (θ), L (θ), M (θ), N (θ) are constants) A spherical component is added to the z-coordinate values on each parting line of the rear face of the lens.

  A lens in which the front surface of the lens is set by a deep curve having a curvature radius of 150 mm or less may be attached to an eyeglass frame having a predetermined deflection angle. In such a case, an inclination corresponding to the warpage angle occurs between the direction of the line of sight of the wearer and the direction of the optical axis of the lens, and as a result, the average dif- ference as seen from the wearer changes. The depth of field extension effect can not be obtained either. For this reason, according to the present invention, even if the lens is inclined according to the warpage angle by further adding a warpage angle correction component that works so as to cancel out the change of the average dioptricity caused when tilting at a predetermined warpage angle, It is possible to obtain a depth-of-field extension effect equal to or close to that when the angle is zero.

  Further, in the design method of the present invention, the rear surface of the lens is divided into a depth of field extension region that causes the depth of field extension effect to be exhibited and the other non-field depth extension regions, The average power stabilization component and the depth of field extension component can be selectively added to the depth of field extension region.

  In the design method of the present invention, a plurality of depth-of-field extension regions for exerting the depth-of-field extension effect are set at different positions in the circumferential direction of the rear surface of the lens, and in the second aspheric component addition step. A different value of constant A can be set in the depth of field extension region of.

The spectacle lens of the present invention is a spectacle lens in which the front surface of the lens is set to have a curvature radius of 150 mm or less,
In the depth of field extension region set on the entire surface or a part of the lens,
The average dioptric power measured with the line of sight of the wearer in a front view and the optical axis of the lens being aligned changes from the optical center of the lens toward the lens peripheral edge to the negative side,
The power change in the first region where the rotational angle of the eye is in the range of 0 degrees to 20 degrees and the power change in the second region where the rotational angle of the eye is in the range of 20 degrees to 40 degrees are both 0.14 to It is characterized by being within the range of 0.46 diopters.

According to the spectacle lens of the present invention, the depth of field is extended farther than the original focus by the depth of field extension component which is changed from the optical center of the lens to the lens peripheral side toward the minus side. You can easily focus on an object that is farther than the original focus.
The greater the change in power from the optical center of the lens to the lens peripheral edge, the greater the depth-of-field extension effect itself, but the greater the power difference between the central portion and the peripheral portion of the lens. In the spectacle lens of the present invention, considering the balance between them, the power variation in the first region on the lens center side and the second region outside the first region are both 0.14 to 0.46. It was within the range of diopter (hereinafter sometimes referred to as "D"). A more preferred range is 0.15 to 0.23 diopters. In this way, while suppressing the power difference between the central portion and the peripheral portion of the lens, the first region at the center of the lens and the second region outside the first region have a certain depth of field or more. An extension effect can be obtained.

The spectacle lens of the present invention is a spectacle lens in which the front surface of the lens is set to have a radius of curvature of 150 mm or less.
In the depth of field extension region set on the entire surface or a part of the lens,
The average dioptric power measured when the optical axis of the lens is inclined at a predetermined deflection angle with respect to the line of sight of the wearer changes from the optical center of the lens to the lens peripheral edge toward the minus side,
The power change in the first region where the rotational angle of the eye is in the range of 0 degrees to 20 degrees and the power change in the second region where the rotational angle of the eye is in the range of 20 degrees to 40 degrees are both 0.14 to It is characterized by being within the range of 0.46 diopters.
In this way, even when mounted on an eyeglass frame having a predetermined deflection angle, the first region on the lens center side, while suppressing the power difference between the center portion and the peripheral portion of the lens, and A certain or more depth of field extension effect can be obtained in the second area outside the one area.

The spectacle lens of the present invention has a refractive index of 1.608, a front surface of the lens is set by a curve of 4.0 to 4.9, and the optical axis of the lens is warped by 10 degrees with respect to the line of sight of the wearer. It is a lens for spectacles used in the state inclined by the angle,
The average dioptric power measured with the line of sight of the wearer in a front view and the optical axis of the lens being aligned changes from the optical center of the lens toward the lens peripheral edge to the negative side,
Vertical diopter of eyeball and diopter of 0.20 to 20 diopter, vertical diopter of eyeball and diopter of eyeball of 20 to 40 diopter of 0.60 ~ 0.70 diopter, lateral variation of eyeball from 0.20 to 0.30 diopter, lateral variation of eyeball from 20 to 40 degree Range of 0.50 to 0.60 diopters, the lateral side of the eye in the lateral direction and the rotational angle range of 0 to 20 degrees in the range of 0.15 to 0.25 diopters, the lateral direction of the eye It is characterized in that the frequency change amount on the nasal side and in the range of 20 degrees to 40 degrees of the rotation angle is 0.50 to 0.60 diopter.
In this way, when mounted on an eyeglass frame having a 10 degree warpage angle, the rotational angle between the central portion of the lens and the central portion is 0 to 20 while suppressing the power difference between the central portion and the peripheral portion of the lens. A certain depth of field extending effect can be obtained in the first region of the range of degrees and in the second region of the range of 20 degrees to 40 degrees of the turning angle outside the first region.

(A) is the whole schematic of the single focus lens of one Embodiment of this invention, (b) is the schematic which expanded the upper half of the lens. It is a figure for demonstrating the single focus lens of FIG. It is a figure for demonstrating the depth of field, (a) is an explanatory view in the case of the single focus lens which concerns on the case of the normal single focus lens, (b) concerning the embodiment. 3 is an explanatory view different from FIG. 3, where (a) is the depth of field in a bright place, (b) is the depth of field in a dark place, and (c) is the lens according to the same embodiment in the dark It is a figure for demonstrating the depth of field of. It is a figure for demonstrating the effect of the single focus lens of FIG. It is an average power distribution contour map of the lens 30a of a comparative example. (A) is a mean power distribution contour map of lens 30b of a comparative example, (b) is a figure showing change of the mean power in the section which met in the direction of the y-axis. (A) is an average power distribution contour map of the lens 30 of an Example, (b) is the figure which showed the change of the average power in the cross section which followed the y-axis direction. It is the figure which showed the photograph image | photographed using the lens of the Example with the photograph image | photographed using the lens of the comparative example. It is explanatory drawing about the flame | frame for spectacles with a sled angle. It is a figure for demonstrating the single focus lens of other embodiment of this invention. It is explanatory drawing about the design method of the single focus lens of FIG. It is explanatory drawing about the design method following FIG. (A) is an average power distribution contour map of the lens 50 of the embodiment measured in a state where the optical axis of the lens is inclined 10 degrees with respect to the line of sight of the wearer, and (b) is a cross section along the y-axis direction It is the figure which showed the change of the average frequency in. It is a mean power distribution contour map of the lens 50 of the Example measured in the state to which the gaze of a wearer's front view and the optical axis of the lens were made to correspond. It is a figure for demonstrating the single focus lens of other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described based on the drawings. In the following description, front and rear, left and right, and upper and lower for the wearer wearing glasses using a lens are respectively front and rear, left and right, and upper and lower in the lens.

In FIG. 1, a lens 1 is a single focus lens for correcting the vision of a wearer. In the lens 1, the back 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). In the lens 1, the front surface 3 is set to have a radius of curvature of 150 mm or less. The axis in the front-rear direction passing through the optical center O of the lens 1 (the base point O _{1 on} the rear surface 2 and the base point O _{2 on the} front surface 3) is taken as the z axis, and the direction toward the rear of the lens 1 is taken 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 ) + δ ₁ + δ ₂ formula (i)
z = r ² / (R ₂ + (R ₂ ² -Kr ² ) ^1/2 ) Formula (ii)

R in formulas (i) and (ii) is the distance from the z axis. That is, in the rear 2 base point O _1, around the reference point O ₂ in the front 3, the left-right direction orthogonal to the z-axis, x-axis vertical axis, respectively, considering an orthogonal coordinate system with the y-axis, r = (X ² + y ² ) ^1/2 . R ₁ and R ₂ are the radius of curvature at the vertex of the surface, and K is 1.
Further, in the formula (i) defining the rear face 2, δ ₁ is represented by Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ (where r is a distance from the z axis, B, C, D, E are constants) It is an average frequency stabilization component. Further, δ ₂ is a depth-of-field extension component represented by Ar ³ (where r is a distance from the z axis and A is a constant).
Therefore, in the lens 1 of this example, the front surface 3 is spherical and the rear surface 2 is aspheric. R ₁ and R ₂ are determined by the prescribed frequency (in this example, S frequency). Here, since the lens 1 is a distance lens for nearsighted people, R ₁ <R ₂ .

The average dioptric power stabilizing component δ ₁ in the formula (i) is an aspheric surface component added to the rear surface of the lens for the purpose of making the average dioptric power substantially constant from the center to the periphery in the lens surface. When the front surface 3 of the lens is set by a deep curve, the power of the region near the lens peripheral edge changes to the positive side. This tendency is more remarkable as the curve of the front surface 3 is deeper. In this example, when designing a lens having a deep curve with a radius of curvature of 150 mm or less on the front surface 3, an average power stabilization component on the rear surface 2 of the lens for the purpose of temporarily correcting the average power within the lens surface δ ₁ is added.

On the other hand, the formula (i) depth of field extension component [delta] ₂ in the direction from the optical center of the lens to the lens periphery, is a non-spherical component to be added to the lens rear surface in order to gradually vary the mean power to the minus side. The aspheric surface component represented by Ar ³ (where A is a positive number) is added to the surface with a constant average power (surface without average power change) from the lens center toward the lens edge It is effective to change the average frequency substantially linearly.

As described above, the lens 1 of this example is a refracting surface of the lens rear surface 2 determined based on the prescribed dioptric power (a spherical surface with a radius of curvature R _{1 in} this example. Hereinafter, it is also referred to as the original spherical surface and is indicated by the symbol S). To which the mean power stabilization component δ ₁ and the depth of field extension component δ ₂ are added (see FIG. 2).

Next, the effect of depth of field extension will be described.
As shown in FIG. 3A, in a normal lens 15 (comparative example) in which the power in the lens plane is constant, only the light rays emitted from the focal position D gather at the imaging position P behind the lens. Therefore, although the object located at the focal position D looks sharp, the object located at a position slightly deviated from the focal position D, such as the positions C and E, disappears sharply and disappears. That is, the depth of field of the lens 15 is shallow.

On the other hand, in the lens 1 shown in FIG. 3B, since the dioptric power changes in the radial direction of the lens due to the depth of field extension component represented by Ar ³ , a certain range including the original focal position D is Rays of light gather at the imaging position P. Therefore, although a slight blur remains even at the focal position D, for example, even at a position slightly deviated from the focal position D, such as positions C and B, the object can be identified with the same degree of sharpness as the focal position D Because of this, the range in focus (the range enclosed by the broken line in the same figure) is expanded, that is, the depth of field of the lens 1 is deep.
Note that when the constant A of the depth of field extension component is a positive value, the depth of field is extended to the side farther than the original focal position D (side of the position of C or B in the figure) .

  The effect of depth of field extension is large especially in dark places with low illumination, such as at night. Hereinafter, description will be made with reference to FIG. In FIG. 4, the eye 20 including the iris 21 is shown.

  FIG. 4A shows a state in a bright place where the illuminance is high, such as daytime, and since the iris 21 is closed and the light flux 22 becomes thin, the range in which the light is concentrated becomes long, and in fact In other words, the depth of field becomes deep (long). Therefore, it can be seen relatively far.

  FIG. 4 (b) shows the state in the dark. Since the iris 21 opens and the ray bundle 22 becomes thick, the range in which light is concentrated becomes short and the depth of field becomes shallow (short). Therefore, an object at a position slightly deviated from the focal position where the light is concentrated becomes difficult to see immediately.

  FIG. 4C shows a state in which the lens 1 is used in a dark place, and the iris 21 is opened and the ray bundle 22 is thickened, but the lens 1 has a depth-of-field extension effect. , Focus on a relatively long distance. Thus, the lens 1 facilitates identification of objects, especially in dark places.

  The effect of such an increase in the depth of field varies with the amount of change in power in the lens surface. In the lens 1 of the present embodiment, as shown in FIG. 5, the visual field is changed when the line of sight is aligned with the object through a region near the center of the lens by changing the power in a substantially linear manner from the optical center toward the lens peripheral edge. The power change amount a in the lens region entering the lens and the power change amount b in the lens region entering the field of view when the line of sight is aligned with the object through the region outside this is substantially the same. An equivalent depth-of-field extension effect can be obtained in the central part of 1 and the area outside this.

  However, the greater the change in power from the optical center of the lens to the lens peripheral edge, the greater the depth of field extension effect itself, but a greater power difference occurs between the central portion and the peripheral portion of the lens. In the lens 1, in consideration of their balance, the first region on the lens center side where the rotational angle of the eye is in the range of 0 to 20 degrees, and the second region of the rotational angle of the eye in the range of 20 to 40 The frequency change amount in the region was set in the range of 0.14 to 0.46 diopters.

Next, a method of 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 prescribed power. The determination method is well known and will not be described in detail here. Next, an aspheric component is added to the refracting surface (original spherical surface S) of the back surface 2 of the lens determined based on the prescribed power. Specifically, adding a first aspheric component adding step of adding the suppressing mean power stabilizing component [delta] ₁ a variation of the mean power, the depth of field to extend the depth of field extension component [delta] ₂ An aspheric surface component is added to the refracting surface of the rear surface 2 by the second aspheric surface component adding process.

In the first aspheric component addition step, an average power stabilization component δ ₁ represented by Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ (where r is a distance from the z axis and B, C, D and E are constants) Is added to the refracting surface of the rear surface 2.

The mean power stabilization component δ ₁ is simulated by ray tracing on the refractive surface shape of the rear surface 2 expressed using the following aspheric surface formula (iii), and the power (specifically, the refractive power in the meridional direction and the sagittal direction To determine the aspheric coefficients B, C, D, and E that are optimal for suppressing changes in the average dioptric power, which is the average of the refractive power of the lens, and to obtain the average dioptric power stabilization component δ ₁ from the values of these aspheric spherical coefficients Can.
z = r ² / (R ₁ + (R ₁ ² -Kr ² ) ^1/2 ) + Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ Formula (iii)
Here, z is a sag value on the rear surface 2, r is a distance from the z axis, R ₁ is a vertex curvature radius, and B, C, D, and E are constants (aspheric coefficients).

Next, in the second aspheric surface component addition step, the depth of field extension component δ ₂ represented by Ar ³ (where r is the distance from the z axis and A is a constant) is determined, and the refracting surface of the rear surface 2 Add to

The constant A in the depth of field extension component is selected from the range of 6.40 × 10 ^{−7 to} 2.40 × 10 ⁻⁵ . If the constant A is in this range in a normal size spectacle lens (diameter 50 to 80 mm), the depth of field extension effect can be obtained moderately and the power difference between the central portion and the peripheral portion of the lens It is because it can control.

  By doing this, the refractive surface shape of the rear surface 2 of the lens 1 defined by the above equation (i) is determined.

Example 1
Based on the following lens data, the following radius of curvature R ₂ of the front 150 mm (details 125.62mm), S counts are to prepare a single-focus lens 30, 30a, 30b of -3.00D, the mean power of the lens Change was measured.
Common lens data are as follows.
S frequency-3.00D
Refractive index n 1.608
Front curve K 4.84 curve (4.84D)
Front curvature radius R ₂ 125.62 mm
Outer diameter 50 50 mm
Center thickness CT 1.10 mm
Furthermore, the curvature radius R ₂ of the front can be obtained by (n-1) / K × 1000.

  The lens 30a (comparative example) has a refractive surface S (see FIG. 1 (b)) determined based on the prescribed power in the shape of the lens rear surface, and both the front surface and the rear surface have spherical shapes.

  The average power distribution of this lens 30a is shown in FIG. The average power distribution is such that the optical axis of the lens coincides with the line of sight of the eyeball at a position separated from the eyeball by a predetermined distance (here, a distance of 25 mm from the refractive surface of the lens rear surface to the rotation center of the eyeball) It measured about the right lens arranged at. FIG. 6 shows the average power distribution obtained in this manner from the rear surface side of the lens. In FIG. 6, what is indicated by dotted lines in the drawing is a 5 mm pitch grid. The same is true for the average power distribution of the lenses 30b and 30 described in detail below.

  As shown in FIG. 6, in the lens 30a in which the front surface of the lens is formed with 4.84 curves (curvature radius 125.62 mm), the average power of the central portion of the lens is −3.12 D or less. It can be seen that when the frequency of the peripheral portion is −2.96 D or more, the frequency changes to the positive side of the central portion in the peripheral portion.

On the other hand, the lens 30 b (comparative example) is obtained by adding a depth of field extension component δ ₂ represented by Ar ³ to the lens rear surface of the lens 30 a. The constant A is 7.68 × 10 ⁻⁶ .

FIG. 7 (a) shows the average power distribution of the lens 30b, and FIG. 7 (b) shows the change of the average power in the cross section along the y-axis direction (vertical direction) of the lens 30b. In the lens 30b on the lens rear surface by adding a non-spherical component consisting of depth of field extension component [delta] _2, power in the lens peripheral portion is changed to the positive side, the rotation angle of the eyeball in FIG. 7 (b) 0 ° While the power change amount a in the first region in the range of -20 degrees is 0.21 diopter, the power change amount b in the second region in the range of 20 degrees to 40 degrees of the eyeball is 0 Since the lens is as small as 13 diopters, the lens 30b can not obtain a sufficient depth-of-field extension effect when the object is viewed through a region near the lens peripheral edge.

Next, the lens 30 (example) is the average power stabilization represented by Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ on the refractive surface of the lens rear surface determined from the prescribed power based on the design method of the present embodiment. and component [delta] _1, an example of adding the depth of field extension component [delta] _2, the represented by Ar ^3. In addition, as for each constant of average frequency stabilization component (delta) ₁ , B is -9.58 * 10 < ^-8 >, C is 1.02 * 10 < ^-10 >, D is 3.03 * 10 < ^-14 >, E is -2. It is 80 × 10 ^-17 . The constant A of the depth of field extension component is 7.68 × 10 ^-6 as in the case of the lens 30b.

8 (a) shows the average power distribution of the lens 30, and FIG. 8 (b) shows the change of the average power in the cross section along the y-axis direction of the lens 30. As shown in FIG. In the lens 30 has been added a non-spherical component on the surface consisting of the mean power stabilizing component [delta] ₁ and the depth of field extension component [delta] ₂ Metropolitan of the lens, compared with the lens 30b, the power in the region close to the lens periphery to the positive side As a result, the power change amount in the region near the lens peripheral edge is increased, that is, the depth-of-field extension effect is enhanced. As shown in FIG. 8 (b), with this lens 30, the power change amount a is 0.18 diopter and the rotation angle of the eye is 20 degrees to 40 in the first region where the rotation angle of the eye is in the range of 0 degrees to 20 degrees. The power change amount b in the second region of the power range is 0.16 diopter, and any power change amount is in the range of 0.14 to 0.46 diopter. FIG. 8B is a diagram showing the change of the average dioptric power in the cross section along the y-axis direction of the lens 30, but in the lens 30, a rotationally symmetric aspheric component is added around the optical axis, Similar frequency variations are obtained in cross sections other than the y-axis direction. With such a lens 30, it is possible to obtain a greater depth-of-field extension effect than in the prior art in a region close to the lens peripheral edge while suppressing the power difference between the central portion and the peripheral edge portion of the lens.

  FIG. 9 is a photograph of a landscape photographed using the single focus lenses 30a (comparative example) and 30 (example). FIG. 9A is a photograph taken using the single focus lens 30 a, and FIG. 9B is a photograph taken using the single focus lens 30. The camera used for shooting was a NIKON D5500 with the lens 30a or 30 mounted under the conditions of F number 16.0 and shutter speed 1/25, and the camera was shot in a state where the power pole on the near side was in focus. When the images in (a) and (b) in FIG. 9 are compared, in the image in (b), the signboard etc. located in the distance is clearer, and the single focus lens 30 has a constant depth of field extension effect. It is understood that it is obtained.

Next, another embodiment of the present invention will be described.
For example, when the lens 30 described in the first embodiment is attached to a frame for glasses having a warpage angle, an inclination corresponding to the warpage angle between the direction of the line of sight of the wearer's front view and the optical axis direction of the lens As a result, the average power seen from the wearer changes, and a predetermined depth-of-field extension effect can not be obtained.
On the other hand, according to the design method of the present embodiment described in detail below, it is possible to impart a suitable depth-of-field extension effect to the lens mounted on the eyeglass frame having a predetermined deflection angle. . Here, as shown in FIG. 10, the warpage angle is a line perpendicular to the line of sight of the wearer in the eyeglass frame 35 in which the rim portion 37 holding the lens is inclined along the face of the wearer. The inclination α of the rim portion 37 with respect to the minute 36.

In the design method of this example, when the lens is inclined at a predetermined deflection angle following the first aspheric component addition step and the second aspheric component addition step similar to the design method of the first embodiment. The surface shape of the rear surface 2 is determined through a third aspheric surface component addition step of adding the warp angle correction component δ ₃ acting to cancel the change of the average dioptric power occurring to the rear surface 2 of the lens. That is, according to this design method, as shown in FIG. 11, on the refractive surface S of the rear surface 2 of the lens determined based on the prescribed diopter, an average diopter stabilization component δ ₁ and a depth of field extension component δ ₂ a bend angle correction component [delta] _3, adds.

  In the following, the third aspheric component addition step will be described by taking, as an example, the case of designing a lens 40 having a depth of field extension effect substantially equivalent to that of the lens 1 obtained by the design method of the first embodiment. .

  In the third aspheric surface component addition step, first, a plurality of dividing lines m extending radially from the optical center O of the lens 40 are set at equal intervals. The number of parting lines m set in the circumferential direction of the lens is within the range of 12 to 360 and can be a number that can divide the lens 40 at equal intervals along the circumferential direction 360 °.

FIG. 12 shows the case where twelve dividing lines m are set. In this case, the dividing lines m are set in the circumferential direction at equal intervals of 30 °. Dividing line m, as shown in the figure, dividing lines m ₁ as a reference on the x-axis are arranged, are set in different positions dividing line m ₂ ~m ₁₂ is the circumferential direction at intervals of subsequent 30 ° . In the figure, p _{1 to} p ₁₂ are regions located between the dividing lines m.

Next, the target power on each dividing line m is obtained from an optical model as shown in FIG. In the figure, 20 is an eye, f ₀ is a line of sight in the front direction of the eye 20, and 25 is a center of rotation of the eye.
A two-dot chain line so that the optical axis of the lens coincides with the line of sight f _{0 of the} eye 20 at a position separated from the eye 20 by a predetermined distance (here, a distance of 25 mm from the refractive surface of the lens rear surface to the center of rotation of the eye) A lens 1 serving as a reference shown in FIG. 1 is disposed, and then a lens 40 is disposed in a state of being inclined with respect to the lens 1 by a deflection angle α.
In such an optical model, draw any sight f ₁ extending to intersect the dividing line m of the lens 40, the frequency of site 41 of the reference lens 1 on the same line '(average power), lens 40 dividing line Let it be the target frequency at the part 41 located on m. Thus, the target frequency on each dividing line m is set.

Next, determine the bend angle correction component [delta] ₃ on the dividing line m. Bend angle correction component [delta] ₃ ^{is, F (θ) r 4 +} G (θ) r 6 + H (θ) r 8 + I (θ) r 10 ( where, r is the distance from the z-axis, F (θ), G ( θ), H (θ), I (θ) are constants (aspheric coefficients), and θ is an angle from the x axis (see FIG. 12)).
Then, simulation is performed by ray tracing for the refracting surface shape of the back surface 2 expressed using the following aspheric surface expression (iv), and the optimum non-uniformness is obtained such that the power on the dividing line m matches or approximates the target power. surface coefficients F (θ), G (θ ), H (θ), obtaining the I (theta), can be the values of these aspherical coefficients obtain the bend angle correction component [delta] ₃ of the dividing line m.
z = r ² / (R ₁ + (R ₁ ^2- Kr ² ) ^1/2 ) + δ ₁ + δ ₂ + F (θ) r ⁴ + G (θ) r ⁶ + H (θ) r ⁸ + I (θ) r ¹⁰ ... Formula (iv)

Next, determine the bend angle correction component [delta] ₃ for each region p ₁ ~p ₁₂ (see FIG. 12) located between the parting line m. For example, in the region p _1, dividing line at the boundary between m ₁ be the same bend angle correction component amount and dividing lines m _1, also the same bend angle correction component amount and dividing line m ₂ at the boundary between the dividing line m ₂ To connect the boundary with dividing line m ₁ to the boundary with dividing line m ₂ smoothly with a cosine curve (half wavelength) along the circumferential direction (see curve w _{1 in} FIG. 12). Derivate the warp angle correction component for p ₁ Deriving a bend angle correction component in a similar manner for the remaining region p ₂ ~p _12. In this way, in the third non-spherical component addition step, the division line m ₁ ~m ₁₂ over a region p ₁ ~p ₁₂ between dividing lines m, aspheric corresponding to the bend angle correction component for each The amount of addition is determined.

Then, on the refractive surface of the rear surface 2 of the lens determined based on the prescribed power, an average power stabilization component δ ₁ for suppressing the fluctuation of the average power, a depth of field extension component δ ₂ for extending the depth of field, in addition, the refractive surface shape of the surface 2 of the lens 40 is determined by further adding bend angle correction component [delta] _3. At this time, J (θ) r ³ + K formed by combining each aspheric surface component obtained in the first, second and third aspheric surface component addition steps with the z-coordinate value on each dividing line m of the lens rear surface (θ) r ⁴ + L (θ) r ⁶ + M (θ) r ⁸ + N (θ) r ¹⁰ (where J (θ), K (θ), L (θ), M (θ), N (θ) Is a constant, and a rotationally asymmetric aspheric component is added around the optical axis. Here, for each constant (aspheric coefficient), J (θ) is the value of A, K (θ) is the value of B + F (θ), L (θ) is the value of C + G (θ), M (θ) Is the value of D + H (θ), and N (θ) is the value of E + I (θ).
According to such a design method, even when the lens is inclined according to the warpage angle, the power change is equivalent to or close to that of the case where the warpage angle is zero, and equal to or similar to the case where the warpage angle is zero. An approximate depth of field extension effect can be obtained.

Example 2
A single-focus lens 50 mounted on an eyeglass frame with a lens front surface having a curvature radius of 150 mm or less (specifically, 125.62 mm), an S power of −3.00 D and a warp angle α of 10 degrees is manufactured. The distribution was measured. The lens data other than the deflection angle is the same as that of the first embodiment.
S frequency-3.00D
Refractive index n 1.608
Front curve K 4.84 curve (4.84D)
Front curvature radius R ₂ 125.62 mm
Outer diameter 50 50 mm
Center thickness CT 1.10 mm

The lens 50 has an average power stabilizing component δ ₁ represented by Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ and a depth of field extending component represented by Ar ³ on the refracting surface of the lens rear surface determined from the prescribed power. δ ₂ and deflection angle correction component δ ₃ are added. In addition, as for each constant of average frequency stabilization component (delta) ₁ , B is -9.58 * 10 < ^-8 >, C is 1.02 * 10 < ^-10 >, D is 3.03 * 10 < ^-14 >, E is -2. It is 80 × 10 ^-17 . The constant A of the depth of field extension component is 7.68 × 10 ⁻⁶ .
Also, constant specifying the bend angle correction component [delta] ₃ on the dividing line m are as shown in Table 1 below. In Table 1, the numbers on the right of E and E represent a power of 10 as a radix and the number on the right of E as an index.

FIG. 14 (a) shows the average power distribution measured with this lens 50 tilted with respect to the eyeball by an angle (10 degrees). The figure is a view showing the lens on the right side from the rear side. In the figure, the left side is the nose side, and the right side is the ear side.
FIG. 14B is a view showing the change of the average dioptric power in the cross section of the lens 50 along the y-axis direction.

In this lens 50, as shown in FIG. 14 (b), the power change amount a is 0.16 diopter and the rotational angle of the eye is 20 degrees to 20 in the first region where the rotational angle of the eye is in the range of 0 degrees to 20 degrees. The power change amount b in the second region in the range of 40 degrees is 0.15 diopter, and any power change amount is in the range of 0.14 to 0.46 diopter.
On the other hand, the x ₁ direction of the frequency change shown in FIG. 14 (a), the power change amount a of 0.22 diopters in the first region of the range rotation angle is 0 ° to 20 °, rotation angle of the eyeball 20 degrees power change amount b in the second region in the range of 40 degrees is 0.21 diopters and for the power change in the x ₂ direction, power change amount a in the first region is 0.16 diopters, in the second region Even when the frequency change amount b is 0.14 diopter and the cross section along the x-axis direction, the frequency change amount a in the first region and the frequency change amount b in the second region are both 0.14 to 0. Within the range of 46 diopters.
Even with this lens 50, it is possible to obtain an effect of extending the depth of field greater than that in the prior art in a region close to the lens peripheral edge while suppressing the power difference between the central portion and the peripheral edge portion of the lens.

FIG. 15 shows the average power distribution of the lens 50 measured in a state in which the line of sight of the wearer in a front view and the optical axis of the lens are matched. The figure is a view showing the lens on the right side from the rear side. In the figure, the left side is the nose side, and the right side is the ear side.
In the figure, mean power is changed to the negative side toward the lens periphery from the optical center O of the lens, the power change in the vertical direction upper side (y-axis y ₁ direction along the) is rotation angle 0 The power change amount a in the first region in the range of 20 degrees to 20 degrees is 0.237 diopters, and the power change amount b in the second region in the range of 20 degrees to 40 degrees of the rotational angle of the eye is 0.644 diopters, Regarding the frequency change in the vertical direction and the lower side (y ₂ direction along the y-axis), the frequency change amount a was 0.23 diopter and the frequency change amount b was 0.631 diopter.
As for the power change in the lateral direction the nose side (x ₁ along the x-axis), power change amount a in the first region of the range rotation angle is 0 degrees to 20 degrees 0.196 diopters, ocular power change amount b rotation angle in the second region in the range of 20 to 40 degrees is 0.53 diopters, for power change in the horizontal direction ear side (x ₂ along the x-axis), power change amount The a was 0.29 diopter, and the frequency change amount b was 0.586 diopter.

That is, the average dioptric power measured in a state where the line of sight of the wearer in a front view and the optical axis of the lens coincide with each other changes from the optical center of the lens toward the lens peripheral edge to the minus side.
Frequency change a in the range of 0 degree to 20 degrees of rotational angle in the vertical direction (y ₁ and y ₂ directions) of the eyeball 0.20 to 0.25 diopter, frequency change in the range of 20 degrees to 40 degree of rotational angle Amount b between 0.60 and 0.70 diopters,
0.20 to 0.30 diopters of the power change amount a to the left and right direction ear side (x ₂ direction) of the eyeball, 0.50 to 0.60 diopters of the power change amount b,
Assuming that the power change amount a to the left and right direction nose side (x ₁ direction) of the eyeball is 0.15 to 0.25 diopter, and the power change amount b is 0.50 to 0.60 diopter, the warpage angle of 10 degrees When mounted on a frame for spectacles having a lens, a power distribution as shown in FIG. 14 is obtained, and while the power difference between the central portion and the peripheral portion of the lens is suppressed, the rotational angle of 0.degree. A certain or more depth of field extending effect can be obtained in the first area in the range of 20 degrees and in the second area in the range of 20 degrees to 40 degrees of the turning angle outside the first area.

Although the embodiment of the present invention has been described in detail, this is merely an example.
The average frequency stabilization component δ ₁ and the depth of field extension component δ ₂ for suitably exerting the depth of field extension effect are added to the entire surface of the back surface 2 and in a partial region of the back surface 2. It is also possible to add selectively.

For example, as shown in FIG. 16A, in the lens 60 in the circumferential direction, the depth of field extension area 62 for exerting the depth of field extension effect and the other non-field depth extension area 64. is partitioned, it is also possible to add the mean power stabilizing component [delta] ₁ and the depth of field extension component [delta] ₂ only the depth of field extension region 62. The average power stabilization component δ ₁ may be added to the non-field depth extension area 64 in addition to the field depth extension area 62.

  When the depth of field extension area 62 is set to the area on the ear side of the lens 60 as in the case of FIG. 16A, in front view, the object is mainly made through the non depth of field extension area 64. While it is possible to visually recognize clearly, when the scenery behind the subject is viewed through the depth of field extension area 62, it is possible to obtain an image with less blur in a wide range by the depth of field extension effect. Such lenses are suitable, for example, for applications such as sports bicycle driving.

Further, as shown in FIG. 16B, a plurality of (here, three) depth-of-field extension areas 62 for exerting the depth-of-field extension effect are set at different positions in the circumferential direction of the lens 60, and it is also possible to add a different depth of field extension component [delta] _2. Specifically, at the time of lens design (in the second aspheric surface component addition step), different values of constant A are set for each region. In this way, it is possible to give each region a desired depth-of-field extension effect.

In the above embodiment, each aspheric component is added to the refractive surface of the rear surface of the lens determined based on the S power, but the refractive surface of the rear surface of the lens determined based on the prescription power is It can be determined based on the C degree, the astigmatic axis AX, etc. in addition to the S degree.
In addition, it is possible to further add a correction prism component for each deflection angle and prescribed power in order to suppress the deviation of the line of sight due to the deflection angle, and further to add an aspheric component taking into consideration the front tilt of the lens. Is also possible.
In addition, the optical center of the lens for spectacles may be provided at a position decentered from the geometric center of the circular lens, and the present invention can be implemented in various modified modes without departing from the scope of the invention. It is.

1, 30, 40, 50, 60 Lens 2 Rear surface 3 Front S refractive surface

Claims (7)

A method of designing a lens for spectacles, wherein the front surface of the lens is set to have a radius of curvature of 150 mm or less,
Assuming that the longitudinal axis passing through the optical center of the lens is the z axis and the direction toward the rear of the lens is the positive direction of the z axis, the z coordinate value of the rear surface of the lens determined based on the prescribed power is Br ⁴ + Cr ⁶ + Dr ⁸ + Er ¹⁰ (where r is the distance from the z axis, B, C, D and E are constants), and an average power stabilization component is added to suppress fluctuations in the average power in the lens surface. 1 aspheric component addition step,
A second aspheric component addition step of adding a depth-of-field extension component represented by Ar ³ (where A is a constant) and extending the depth of field to the z-coordinate value of the rear surface of the lens; The design method of the lens for spectacles characterized by having. On a plurality of dividing lines set so as to extend radially from the optical center of the lens, F (θ) r ⁴ + G (θ) r ⁶ + H (θ) r ⁸ + I (θ) r ¹⁰ (where F (θ)) , G (.theta.), H (.theta.), I (.theta.) Are constants and .theta. Is the angle from the x-axis orthogonal to the z-axis), and the optical axis of the lens with respect to the line of sight of the wearer Further comprising a third aspheric component addition step of adding to the z-coordinate value of the rear surface of the lens a deflection angle correction component that acts to cancel out the change of the average dioptric power generated when tilting L at a predetermined deflection angle;
The first, second, third combining aspherical each aspheric surface components obtained in component addition step comprising ^{J (θ) r 3 + K} (θ) r 4 + L (θ) r 6 + M (θ) r 8 The lens is a rotationally asymmetric aspheric component represented by + N (θ) r ¹⁰ (where J (θ), K (θ), L (θ), M (θ), N (θ) are constants), and the lens The method for designing a lens for spectacles according to claim 1, characterized in that it is added to the z-coordinate value on each division line of the rear surface of the lens.   The rear surface of the lens is divided into a depth-of-field extension region that exerts the depth-of-field extension effect and other non-depth-of-field extension regions, and the rear surface of the lens is divided relative to the depth-of-field extension region. The method for designing a spectacle lens according to any one of claims 1 and 2, characterized in that an average power stabilization component and a depth of field extension component are selectively added.   A plurality of depth-of-field extension regions for exerting the depth-of-field extension effect are set at different positions in the circumferential direction of the rear surface of the lens, and in the second aspheric surface component addition step The method for designing a spectacle lens according to any one of claims 1 and 2, wherein values of different constants A are set. An eyeglass lens in which the front surface of the lens is set to have a curvature radius of 150 mm or less,
In the depth of field extension region set on the entire surface or a part of the lens,
The average dioptric power measured with the line of sight of the wearer in a front view and the optical axis of the lens being aligned changes from the optical center of the lens toward the lens peripheral edge to the negative side,
The power change in the first region where the rotational angle of the eye is in the range of 0 degrees to 20 degrees and the power change in the second region where the rotational angle of the eye is in the range of 20 degrees to 40 degrees are both 0.14 to An eyeglass lens having a range of 0.46 diopters. An eyeglass lens in which the front surface of the lens is set to have a curvature radius of 150 mm or less,
In the depth of field extension region set on the entire surface or a part of the lens,
The average dioptric power measured when the optical axis of the lens is inclined at a predetermined deflection angle with respect to the line of sight of the wearer changes from the optical center of the lens to the lens peripheral edge toward the minus side,
The power change in the first region where the rotational angle of the eye is in the range of 0 degrees to 20 degrees and the power change in the second region where the rotational angle of the eye is in the range of 20 degrees to 40 degrees are both 0.14 to An eyeglass lens having a range of 0.46 diopters. Glasses used with refractive index of 1.608, lens front surface set with 4.0 to 4.9 curve, and the optical axis of the lens is inclined at a 10 degree warp angle with respect to the line of sight of the wearer in front view A lens for
The average dioptric power measured with the line of sight of the wearer in a front view and the optical axis of the lens being aligned changes from the optical center of the lens toward the lens peripheral edge to the negative side,
0.20 to 0.25 diopters in the vertical direction of the eyeball and in the range of 0 ° to 20 ° of the rotation angle;
0.60 to 0.70 diopters of frequency change in the vertical direction of the eyeball and in the range of 20 to 40 degrees of rotational angle
0.20 to 0.30 diopters of frequency change in the lateral ear side of the eye and in the range of 0 ° to 20 ° of the rotation angle;
0.50 to 0.60 diopters of frequency change in the lateral ear side of the eye and in the range of 20 to 40 degrees of rotational angle,
0.15 to 0.25 diopters of frequency change of the right and left direction nasal side of the eyeball and the rotation angle in the range of 0 to 20 degrees,
What is claimed is: 1. A lens for eyeglasses, characterized in that the degree of frequency change in the right and left direction nasal side of the eyeball and in the range of 20 degrees to 40 degrees of rotational angle is 0.50 to 0.60 diopter.