WO2013137179A1

WO2013137179A1 - Eyeglass lens and bifocal eyeglasses

Info

Publication number: WO2013137179A1
Application number: PCT/JP2013/056603
Authority: WO
Inventors: 恵介太田
Original assignee: 東海光学株式会社
Priority date: 2012-03-14
Filing date: 2013-03-11
Publication date: 2013-09-19
Also published as: JPWO2013137179A1

Abstract

[Problem] To provide: an eyeglass lens that has a wider range of clear vision and is easier to use in relation to an eyeglass lens in which the spherical power can be changed by arranging two lens elements so as to overlap each other in the front-to-rear direction and by relatively sliding the lens elements with respect to each other; and bifocal eyeglasses equipped with such lenses. [Solution] Disclosed is an eyeglass lens in which a first lens element and a second lens element are arranged in parallel in the front-to-rear direction such that the optical axes thereof are parallel, and in which the S power can be changed by relatively moving the lens elements in opposite directions along a direction approximately orthogonal to the optical axes thereof. In this eyeglass lens: a curve expressed by the equation below is compounded, as an additional amount of sag, onto the object-side surface of the first lens element, which is arranged on the outside, and the eyeball-side surface of the second lens element, which is arranged on the inside; the two lens elements are arranged in parallel so as to match the x axis direction and the y axis direction of each lens element; the two lens elements can relatively move in opposite directions only along the x axis direction; and the front surface and/or the back surface of the respective lens elements are/is made aspherical. g(x,y)=(A/6)x³+(A/2)xy² (wherein A≠0)

Description

Eyeglass lenses and bifocal glasses

The present invention relates to a spectacle lens in which two lens elements are overlapped in the front-rear direction and the S power can be changed by relatively shifting the lens elements, and a bifocal spectacle equipped with such a lens. .

Conventionally, spectacles for setting an arbitrary S power (spherical power) of a user by combining two lens elements have been proposed. For example, the following Non-Patent Document 1 discloses spectacles using an Alvarez lens developed as spectacles at the time of disaster or emergency. The spectacles are spectacles composed of two lens elements on the left and right sides, and the knobs are rotated to slide the lenses, and the degree of overlapping of the lenses is adjusted to change the spherical power.

However, the spectacle lens of Non-Patent Document 1 is supposed to be used when the original spectacles are lost in a disaster or emergency, and is not necessarily easy to use. In this example, the S power variable region covers from −6D (diopter, hereinafter abbreviated) to + 3D, and since the aberration is not corrected, the clear vision region is narrow and the performance is not satisfactory as a spectacle lens. However, by sliding the two lens elements in this way, the spectacles can be used for presbyopia by changing the spherical power during near vision and near vision while using as a single focus lens. A lens can be expected to be in sufficient demand by applying it to bifocal glasses. For this reason, this type of spectacle lens has been required to be applicable to bifocal glasses that can be used in daily life other than disasters and emergencies that have a wider clear visual field and are easier to use.
The present invention has been made paying attention to such problems existing in the prior art. It is an object of the present invention to provide a spectacle lens that can change the spherical power by overlapping two lens elements in the front-rear direction and relatively shifting the spectacle lens, and a spectacle lens that has a wider clear visual field and is easy to use. The object is to provide bifocal glasses equipped with a lens.

In order to solve the above-described problem, in the first means, the first and second lens elements are arranged in parallel in the front-rear direction so that the optical axes are parallel, and relatively in a direction approximately orthogonal to the optical axis. In a spectacle lens that can be moved in the reverse direction to change the S power, the object-side surface of the first lens element arranged outside and the eyeball-side surface of the second lens element arranged inside Are combined as an additional sag amount with a function g (x, y) of the same or different curved surface such that the partial derivative g _xy obtained by partial differentiation with x and y is a function or constant only of y. The gist of the invention is that both lens elements can be moved in the opposite direction only in the x-axis direction, and at least one surface of the both lens elements is aspherical to reduce aberrations. To do.

Further, in the means 2, in addition to the structure of the means 1, a function g (x, y) of a cubic surface synthesized as an additional sag amount in the first and second lens elements is defined by the following expression. To do.

Further, in the means 3, in addition to the structure of the means 1 or 2, the reference surface for synthesizing the additional sag amount with the first and second lens elements has a spherical shape, a flat surface, or an astigmatic surface. Is the gist.
Further, the gist of the means 4 is that the variable range of the S frequency is within 4D in addition to the structure described in any of the means 1 to 3.

Further, the gist of the means 5 is that, in addition to the structure described in any one of the means 1 to 4, one of the first and second lens elements is fixed and only the other is movable. .
Further, the gist of the means 6 is that, in addition to the configuration described in the means 5, the aspherical design is performed only on the lens element on the fixing side among the first and second lens elements.
Further, the gist of the means 7 is that, in addition to the configuration described in the means 5 or 6, the astigmatism correction design is performed only on the fixed lens element among the first and second lens elements. .
Further, in the means 8, in addition to the structure described in any one of means 5 to 7, the first or second lens that shifts the refractive power related to the light beam transmitted through the first and second lens elements to the plus side. The gist is that the prism change due to the movement of the element is an increase in the in-prism or a decrease in the out-prism.
Further, the gist of the means 9 is that, in addition to the configuration described in any one of the means 5 to 8, the second lens element side is fixed and only the first lens element side is movable.
The gist of the means 10 is that, in addition to the configuration described in any one of the means 1 to 9, a spectacle lens is mounted on the bifocal glasses described in any of the means 1 to 11.

By configuring as described above, the first and second lens elements are arranged in parallel in the front-rear direction so that the optical axes are parallel, and are relatively opposite to the direction approximately orthogonal to the optical axis. It is possible to provide a spectacle lens having a small clear astigmatism and a wide clear viewing area, in which the spherical power can be changed by moving the lens to.
Here, when the horizontal direction is set as the x-axis direction and the vertical direction is set as the y-axis direction, the object-side surface of the first lens element arranged outside and the eyeball of the second lens element arranged inside It is necessary to synthesize a cubic surface function g (x, y) such that the partial derivative g _xy (x, y) is represented by a function of y only or a constant on the side surface as an additional sag amount. is there. The partial derivative g _xy (x, y) is a derivative obtained by partial differentiation of the function g (x, y) with x and y.

Here, the reason why the partial derivative g _xy (x, y) is expressed by a function or constant only of y will be described.
All power represented by S degrees · C power-astigmatic axis, and mdp component representing the mean power, and J ₀₀ component is the average power is an astigmatic power in the horizontal vertical 0D, 45 ° oblique astigmatism mean power is power is J ₄₅ component is 0D, can be represented is separated into three components of Jackson cross cylinder.
Here, J ₀₀ component and J ₄₅ component caused by 3-dimensional curved surface which is arranged in two lens elements will be described. Each of the three-dimensional curved surface is required to have the property that the value of J ₀₀ component and J ₄₅ component surface astigmatism in everywhere is determined only by the y coordinate regardless of the x coordinate. This is because the two lens elements are used while being relatively moved in the x-axis direction. And it is necessary not to generate astigmatism when the two lens elements are relatively moved in the x-axis direction.
Assuming that the value of J ₀₀ component or J ₄₅ component was different values by the x-coordinate, the value of J ₀₀ component or J ₄₅ components of power related to light transmitted through the two lens elements are lens elements x axis direction It will change by moving to. This means a variation in the power of astigmatism and is excluded from the present invention when the lens element has such a curved surface.
On the other hand, even if the value of J ₀₀ component and J ₄₅ component of the surface astigmatism differ by y coordinate, corresponding two points y coordinates are equal to approximately (rays of light when there light passes through the two surfaces Even if the lens element is tilted with respect to the axis, if the lens element is sufficiently thin, the difference between the y-coordinates of the two corresponding points is small. Even if the expressions of the cubic surfaces of the two lens elements are different, the astigmatism power generated in the transmitted light beam by the corresponding two-point surface astigmatism does not change even if the lens element is moved in the x-axis direction. It is constant.
The J ₀₀ component surface astigmatism, which is the difference in the refractive power in the horizontal direction of the refractive power and the vertical direction. It is proportional to the difference between the value of the derivative that is second-order partial differentiated by x and the value of the derivative that is second-order partially differentiated by y, so that the value of the difference is determined only by the y coordinate regardless of the x coordinate. To.
The J ₄₅ component of surface astigmatism is the difference between the refractive power in the oblique 45 degree direction and the refractive power in the oblique 135 degree direction. It is proportional to the value of the derivative obtained by partial differentiation with respect to x and y, and the value is determined only by the y coordinate, not by the x coordinate.
Here, the reason why the _J45 component is proportional to the derivative value obtained by partial differentiation with respect to x and y will be described. Assuming a certain function f (x, y) = Axy, A> 0 representing the surface shape, the value of the function f is proportional to the square of the distance as the distance from the origin of x = y = 0 on the straight line y = x. It becomes a positive value that increases and becomes a negative value that decreases in proportion to the square of the distance as it moves away from the origin of x = y = 0 on the line y = −x. Such a surface has an average value of surface refractive power of 0, and has an astigmatism in which the axis is oblique. The strength of the surface astigmatism is proportional to A.
Specifically, the partial derivatives of each of the three-dimensional curved surface ^{∂ 2 g (x, y)} / ∂x 2 -∂ 2 g (x, y) / ∂y 2
And ∂ ² g (x, y) / ∂x∂y
Is a function or constant that is only y. However, “unrelated to the x coordinate and determined only by the y coordinate” and “constant everywhere” are approximate meanings, and an allowable error may occur in the lens peripheral region.

As the cubic surface function g (x, y), specifically, for example, the one represented by the above equation (1) can be considered. In equation 1, the derivative is
∂ ² g (x, y) / ∂ x ² −∂ ² g (x, y) / ∂ y ² = 0
∂ ² g (x, y) / ∂x∂y = Ay
And satisfies the above conditions.
Further, when the first lens is fixed and the second lens is moved to the ear side, the cubic surface of the first lens is a curved surface with the ear side convex forward with respect to the pupil position. (For example, an image like the explanatory diagram of FIGS. 19A to 20B). In this case, of course, the third curved surface of the second lens is convex rearward on the nose side.
Further, it is necessary to slide both the first and second lens elements facing each other while completely contacting each other. For this reason, the facing surfaces must be formed of a flat surface or a spherical surface having the same curve.

The reference surface for synthesizing the additional sag amount with the first and second lens elements is preferably a spherical surface, a flat surface, or an astigmatic surface in terms of ease of lens design.
If the base shape of either of the two lens elements produces a refracting power with respect to light rays that pass through it, this is referred to as the base refracting power. When the base refractive power is not constant depending on the location on the lens surface, the distribution of the base refractive power changes as the lens element moves. If the refractive power for each cross-sectional direction changes at each point on the lens surface, the astigmatism power at that point changes, but in the present invention, it is not preferable that the astigmatism power change as the lens element moves. It is not preferable that the distribution of the base refractive power changes greatly with the movement of the lens element. From the above, it is preferable that the base refractive power is as constant as possible in each cross-sectional direction. However, it does not matter that the refractive powers are different for different cross-sectional directions. For example, an astigmatic lens having both sides as a trick surface, or a single-sided spherical surface and a one-sided trick surface can have such a base shape.
Further, a shape obtained by adding an element of inclination represented by the x1st order and y1th order equations to these surfaces can also be a base shape.
Also, if the y-coordinate is constant and the base refractive power is constant for each cross-sectional direction on the direction along the x-axis direction, i.e., on the straight line represented by y = constant, the cross-sectional directions are different at points where the y-coordinate is different Even if the base refractive powers of the two lenses are different, the refractive power does not change when the two lens elements are relatively moved in the x-axis direction. Therefore, if it is the x0th order, any term higher than the y3th order can be added to the base shape as long as it is smooth even if it is a special function of only y not including x.
Further, the shapes (base shapes) before the addition sag amounts of the first and second lens elements are combined may be the same or different. In the case where the refractive power of the second lens element is larger than the refractive power of the first lens element, the base shape is naturally different.

In addition, when changing the S power, it is possible to suppress the occurrence of aberrations without causing unreasonableness in the lens design by limiting to the change of the refractive power covering from about infinity to about 25 cm in front. In order to obtain such refractive power, it is preferable that the variable range of the S power is within 4D.

When changing the S power, it is preferable to fix one of the first and second lens elements and move only the other. This is because it is mechanically simple to fix one rather than move both when it is held on the spectacle frame.
However, there are some problems when only one lens element is moved. First, astigmatism tends to be larger than when both lens elements are moved uniformly. When only one lens element is moved, a part far away from the optically unused area before the movement is used, and the sag amount of the cubic curved surface to be added in the separated area is This is because the light beam transmitted through the surface tends to move away from an approximate behavior, and higher-order aberrations including astigmatism tend to increase.
However, in the present invention, astigmatism is mitigated because the aspherical surface is formed as described above.
Also, when only one lens element is moved, there is a problem of prism generation. Now, assume that the same amount of the first and second lens elements having the same curved shape are moved from the state of FIG. 19A to the pupil position of the eye as shown in FIG. 19B. In this case, since the slopes of the curved surfaces of both lens elements are arranged in parallel, no prism is theoretically generated.
However, when one lens element is fixed (here, the eyeball side) and only the other lens element (here, the object side) is moved as shown in FIGS. Since the slopes of the curved surfaces of the elements do not match, prisms are generated. Therefore, when fixing one lens element, it is necessary to suppress the prism small. For example, it is necessary to design the function g (x, y) of the cubic surface so that the prism becomes small.
Further, it is conceivable to set the refractive power of the lens element on the fixing side to be larger than the refractive power of the lens element on the moving side as the prism suppressing means. This is for the following reason.
The fact that the lens has refractive power corresponds to having a prism distribution. For example, if the central prism is 0 in a lens having a minus power, there is a prism having a lens peripheral direction as a base direction (a thicker lens peripheral direction) at a position away from the center. The amount of prism increases as the distance from the center of the lens increases. The amount of prism generated is proportional to the lens power. When such a lens is moved with respect to the eye, the amount of prism felt by the wearer's eyes changes. Therefore, if only one lens element is moved, it is preferable to make the amount of prism as small as possible in a region other than the center of the lens element to be moved.
Further, it is preferable that the lens element on the fixing side is the second lens element side on the eyeball side (rear side). This is because if the lens to be moved is on the object side, it does not hit the temple of the spectacle frame.

Further, it is preferable that the aspherical design and the astigmatism correction design are performed only on the lens element on the fixed side. This is because these designs are designed on the assumption that the pupil position is fixed. For example, in the astigmatism correction design, the astigmatism axis direction is determined. The distribution of the optical effect due to the aspherical surface is shifted with respect to the eye. Furthermore, the fact that the power of astigmatism moves with respect to the eye means that the “prism at a position away from the center” that exists accompanying the cross-sectional refractive power in a certain direction moves.
Further, it is preferable that the first and second lens elements are arranged so that a prism generated by the movement of the moving lens element becomes an in-prism. This will be described with reference to FIGS. 20A and 20B and FIG. In FIGS. 20A and 20B, the cubic curved surface formed on the object side surface of the first lens element that is outside the left eye is a curved surface that is thick on the ear side and thin on the nose side. . On the other hand, the cubic curved surface formed on the eyeball side surface of the second lens element is a curved surface that is thick on the nose side and thin on the ear side. When the first lens element is moved to the ear side from FIG. 20A in such an arrangement state (state of FIG. 20B), an in-prism for the left eye is generated. Basically, the prism should be suppressed. However, as shown in FIG. 21, the in-prism has an effect of easily performing convergence in near vision, and thus is not necessarily disadvantageous as a spectacle lens. Therefore, if the generation of a prism is unavoidable when one lens element is fixed, it is preferable to move the first and second lens elements so as to be an in-prism. In that case, the second lens element side is preferably fixed. In FIGS. 20A and 20B, the first lens element is moved into the in-prism when moved to the ear side. However, if the curve characteristic of the cubic surface is reversed, it is moved to the nose side. It becomes a prism.

In the present invention, the clear vision range is wide and easy to use in the bifocal glasses equipped with the spectacle lens in which the spherical power can be changed by overlapping and shifting the two lens elements in the front-rear direction.

(a) And (b) is a distribution map of the average power and astigmatism in Example 1, respectively. (a) And (b) is a distribution map of the average power and astigmatism in Example 2, respectively. (a) And (b) is a distribution map of the average power and astigmatism in Example 3, respectively. (a) And (b) is a distribution map of the average power and astigmatism in Example 4, respectively. (a) And (b) is a distribution map of the average power and astigmatism in the comparative example 1, respectively. (a) And (b) is a distribution map of the average power and astigmatism in the comparative example 2, respectively. 6 is a distribution diagram of average power and astigmatism at a reference position in Example 5. FIG. FIG. 10 is a distribution diagram of average power and astigmatism when both lens elements in Example 5 are moved equidistantly. FIG. 10 is a distribution diagram of average power and astigmatism when the second lens element in Example 5 is fixed. 10 is a distribution diagram of average power and astigmatism at a reference position in Example 6. FIG. FIG. 10 is a distribution diagram of average power and astigmatism in a state where both lens elements in Example 6 are moved equidistantly. FIG. 10 is a distribution diagram of average power and astigmatism in a state where the second lens element in Example 6 is fixed. 10 is a distribution diagram of average power and astigmatism at a reference position in Comparative Example 3. FIG. FIG. 10 is a distribution diagram of average power and astigmatism when both lens elements in Comparative Example 3 are moved by an equal distance. FIG. 10 is a distribution diagram of average power and astigmatism in a state where the second lens element is fixed in an actual comparative example 3. 10 is a distribution diagram of average power and astigmatism at a reference position in Comparative Example 4. FIG. FIG. 10 is a distribution diagram of average power and astigmatism when both lens elements in Comparative Example 4 are moved equidistantly. FIG. 10 is a distribution diagram of average power and astigmatism in a state where the second lens element in an actual comparative example 4 is fixed. (A) is explanatory drawing explaining the case where the lens element of the same refractive power which has a curved surface of the same characteristic is moved by an equal amount in the reverse direction before the movement, (b). (A) is explanatory drawing explaining the case where only one of the lens elements of the same refractive power which have the curved surface of the same characteristic after movement and (b) after movement is moved. Explanatory drawing explaining that transmitted light is refracted inside by generation | occurrence | production of an in prism.

1. Regarding the structure of eyeglasses The eyeglass lens of the embodiment is actually mounted on a frame and used as bifocal glasses. The spectacle lens had a meniscus lens shape, and in all the following examples, a lens having a diameter of 50 mm and a material refractive index of 1.600 was used. The first lens element arranged on the outside and the second lens element arranged on the inside are in surface contact with a base curve surface having a predetermined spherical shape (which must not be an aspheric surface). Both lens elements are mounted on the frame so that the x-axis direction is horizontal. As a means for moving the lens element, for example, a method is conceivable in which a gear (pinion) is manually rotated with respect to a rack fixed to the lens and moved left and right with respect to the frame. In the following examples and comparative examples, the x-axis direction and the y-axis direction of the first and second lens elements are made to coincide with each other, and the position where the outer peripheries of the first and second lens elements coincide with each other is set as the reference position The optical characteristics in the case of moving in the axial direction were verified.
2. EXAMPLES Hereinafter, specific examples of the present invention will be described with reference to the drawings. Each of the following examples is a spherical sag function.

And a sag function of a cubic surface given to the object-side surface of the first lens element and the eyeball-side surface of the second lens element arranged on the inner side is represented by the above equation (1).
In addition, the aspherical sag functions in Examples 1 to 4 are represented by the following equations (3) and (4). Equation 3 is a functional equation that gives an aspherical sag of a rotationally asymmetric aspheric surface, and Equation 4 is a functional equation that gives an aspherical sag of a rotationally symmetric aspheric surface. In Examples 1 to 4, the result of both equations is added to give an aspherical sag.
In addition, the aspherical sag function in Examples 5 and 6 is expressed by the following equations 5 to 7. In Examples 5 and 6, the results of the three expressions are added to give an aspherical sag.

Hereinafter, the coefficient A is referred to as an Alvarez coefficient.
In the following example, a lens was designed by adding a synthetic curved surface given by these functions to the base shape, and the average power and astigmatism were calculated.

(Example 1)
In Example 1, it is assumed that the second lens element is fixed and only the first lens element is moved. The moving direction of the first lens element during the transition from the far vision state to the near vision state is the ear side direction.
The setting conditions of the eyeglass lens of Example 1 are as follows. The cubic curved surface is arranged so that the ear side is convex forward with respect to the pupil position in the first lens element. The following examples and comparative examples are the same. In Example 1, the aspherical sag is provided only on the back surface side of the second lens element.
First lens element Front curve 0, back curve 0 (1.523 conversion)
Alvarez coefficient (A) 0.0005
Second lens element Front curve 0, back curve 0 (1.523 conversion)
Alvarez coefficient (A) 0.0005
Aspheric coefficient of each term of hA (r) 4th order term: 4 × 10 ⁻⁷ , 5th order term: −4 × 10 ⁻⁹ , 6th order term: 1 × 10 ⁻¹² , 8th order term: 1 × 10 ⁻¹⁵
Aspheric coefficient of each term of hB (r) 4th order term: 1.5 × 10 ⁻⁷ , 5th order term: 1.5 × 10 ⁻⁹ , 6th order term: 0, 8th order term 0

FIG. 1A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which the first lens element is moved 13.5 mm in the horizontal direction in the eyeglass lens of the first embodiment. Thick contour lines are in 1D increments, and thin contour lines are in 0.25D increments (the same applies to the following examples and comparative examples). In this state, the S frequency was −4.00 D, and the prism was 2.73 on the in side. It is a slightly higher prism.
FIG. 1B is a distribution diagram based on the average power and astigmatism values in a state where the first lens element is moved 6.70 mm in the horizontal direction. In this state, the S frequency was −2.00 D, and the prism was 0.67 on the in side. It is not a problem that such a prism is generated on the in side. Since the second lens element is fixed, the astigmatism tends to increase. However, in Example 1, since the second lens element is aspherical, the second lens element is compared with Comparative Example 2 described later. Good results were obtained for both the average power and astigmatism.

(Example 2)
In the second embodiment, both lens elements are moved equidistantly in opposite directions. Further, the aspherical sag is given only to the back side of the second lens element.
The setting conditions of the spectacle lens of Example 2 are as follows.
First lens element Front curve 0, back curve 0 (1.523 conversion)
Alvarez coefficient (A) 0.0005
Second lens element Front curve 0, back curve 2 (1.523 equivalent)
Alvarez coefficient (A) 0.0005
Aspheric coefficient of each term of hA (r) 4th order term: 4 × 10 ⁻⁷ , 5th order term: −4 × 10 ⁻⁹ , 6th order term: 1 × 10 ⁻¹² , 8th order term: 1 × 10 ⁻¹⁵
Aspherical coefficient of each term of hB (r) 4th order term: 1 × 10 ⁻⁷ , 5th order term: 1 × 10 ⁻⁹ , 6th order term: 0, 8th order term 0

FIG. 2A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which both lens elements are moved in the horizontal direction by 3.36 mm (totally less than 6.70 mm), respectively. In this state, the S frequency was −4.00 D, and the prism was 0.67 on the out side. Although an out prism is not preferable, in this case, if both lens elements are rotated 180 degrees in opposite directions, the direction of the curve is reversed and the prism is generated on the in side, so there is no problem.
FIG. 2B is a distribution diagram based on the average power in the near vision state and the numerical value of astigmatism at the reference position in which the both lens elements are matched without shifting in the spectacle lens of the second embodiment. In Example 2, the refractive power of the first lens element is 0D, and the refractive power of the second lens element is 2D. In other words, the S frequency is set to -2.00 D when both lens elements are not shifted. The prism was zero.
The prism is generated even though both lens elements are moved by the same distance because the refractive powers of both lens elements are unbalanced.
In Example 2, since both lens elements are moved by the same distance, the astigmatism generated when the second lens element as in Example 1 is fixed is improved, but the refractive power of both lens elements is improved. Astigmatism resulting from imbalance occurs. However, astigmatism is improved as a total due to the aspherical shape.

(Example 3)
In Example 3, the second lens element is fixed and only the first lens element is moved. The moving direction of the first lens element during the transition from the far vision state to the near vision state is the ear side direction. Further, the aspherical sag is given only to the surface side of the second lens element.
The setting conditions of the spectacle lens of Example 3 are as follows.
First lens element Front curve 0, back curve 0 (1.523 conversion)
Alvarez coefficient (A) 0.0005
Second lens element Front curve 0, back curve 2 (1.523 equivalent)
Alvarez coefficient (A) 0.0005
Aspherical coefficient of each term of hA (r) 4th order term: −2 × 10 ⁻⁷ , 5th order term: 4 × 10 ⁻⁹ , 6th order term: −1 × 10 ⁻¹² , 8th order term : -1 × 10 ⁻¹⁵
Aspherical coefficient of each term of hB (r): Fourth-order term: −1 × 10 ⁻⁷ , fifth-order term: −1 × 10 ⁻⁹ , sixth-order term: 0, eighth-order term 0

FIG. 3A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which the first lens element is moved by 6.54 mm in the horizontal direction. In this state, the S frequency was −4.00 D and the prism was 0.
FIG. 3B is a distribution diagram based on the average power of the near vision state and the numerical value of astigmatism at the reference position in which the both lens elements are matched without shifting in the spectacle lens of the third embodiment. In Example 3, the refractive power of the first lens element is 0D, and the refractive power of the second lens element is 2D. In other words, the S frequency is set to -2.00 D when both lens elements are not shifted. It was 0.66 on the in side. The occurrence of such a prism on the in side is not a problem.
In Example 3, astigmatism easily occurs because the second lens element is fixed, but the astigmatism is improved because the refractive power is given only to the second lens element side. . Further, by providing refractive power only to the second lens element side, for example, the prism is also smaller than in the first embodiment. In addition, astigmatism is improved as a total because it is aspherical.

(Example 4)
In Example 4, the second lens element is fixed, and only the first lens element is moved. The moving direction of the first lens element during the transition from the far vision state to the near vision state is the ear side direction. An aspherical sag is provided on the back surface of the second lens element.
The setting conditions of the spectacle lens of Example 3 are as follows.
First lens element Front curve 0, back curve 0 (1.523 conversion)
Alvarez coefficient (A) 0.0005
Second lens element Front curve 0, back curve 2 (1.523 equivalent)
Alvarez coefficient (A) 0.0005
Aspherical coefficient of each term of hA (r) 4th order term: 3 × 10 ⁻⁷ , 5th order term: −4 × 10 ⁻⁹ , 6th order term: 1 × 10 ⁻¹² , 8th order term: 1 × 10 ⁻¹⁵
Aspherical coefficient of each term of hB (r) 4th order term: 1 × 10 ⁻⁷ , 5th order term: 1 × 10 ⁻⁹ , 6th order term: 0, 8th order term 0

FIG. 4A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which the first lens element is moved 6.54 mm in the horizontal direction. In this state, the S frequency was −4.00 D, and the prism was 0.
FIG. 4B is a distribution diagram based on the average power in the near vision state and the numerical value of astigmatism at the reference position where the lens elements of the spectacle lens of Example 4 are matched without shifting. In Example 4, the refractive power of the first lens element is 0D, and the refractive power of the second lens element is 2D. In other words, the S frequency is set to -2.00 D when both lens elements are not shifted. It was 0.68 on the in side. The occurrence of such a prism on the in side is not a problem.
In Example 4, since the second lens element is fixed, astigmatism is likely to occur. However, since the refractive power is applied only to the second lens element side, the astigmatism is improved. ing. Moreover, the prism is also made small by giving refractive power only to the second lens element side. In addition, astigmatism is improved as a total because it is aspherical. Although the improvement tendency was the same as that of Example 3, since the aspherical sag was given to the back side of the second lens element, the whole given to the front side was better than Example 3.

Hereinafter, the difference between the first lens element and the second lens element in comparison with the first embodiment will be described for a comparative example in which aspherical processing is not performed using the same curve size, Alvarez coefficient, and aspheric coefficient as the first embodiment. To do.
(Comparative Example 1)
In Comparative Example 1, both lens elements are moved equidistantly in opposite directions.
FIG. 5A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which the first lens element is moved 6.68 mm (totally less than 13.5 mm) in the horizontal direction. . In this state, the S frequency is −4.00 D and the prism is 0.
FIG. 5B shows the average power and astigmatism in the near vision state in which both lens elements are moved by 3.34 mm (totally less than 6.70 mm) in the horizontal direction in the eyeglass lens of Comparative Example 1 as well. It is a distribution map based on the numerical value of an aberration. In this state, the S frequency is -2.00 D, and the prism is 0 because the lens having the same refractive power is moved by an equal amount.
In Comparative Example 1, since both lens elements are moved by the same distance, for example, compared with Example 1 above, there is not much difference. However, in Example 1, since the second lens element is fixed, there are many elements that generate astigmatism. However, since the aspherical surface is used, it is alleviated and both lens elements are equidistant. Good results comparable to those obtained when moved.

(Comparative Example 2)
In Comparative Example 2, it is assumed that the second lens element is fixed and only the first lens element is moved. The moving direction of the first lens element during the transition from the far vision state to the near vision state is the ear side direction.
FIG. 6A is a distribution diagram based on the average power and astigmatism values in the distance vision state in which the first lens element is moved 6.70 mm in the horizontal direction. In this state, the S frequency was −4.00 D, and the prism was 2.73 on the in side.
FIG. 6B is a distribution diagram based on the average power and astigmatism values in the near vision state in which the first lens element is moved 6.70 mm in the horizontal direction in the eyeglass lens of Comparative Example 1. In this state, the S frequency was −2.00 D, and the prism was 0.67 on the in side.
This comparative example 1 is different only in that it is not aspherical. Also in Example 1, astigmatism is not suppressed so much because the refractive powers of both lens elements are equal, but astigmatism does not occur largely because it is aspherical, and astigmatism in Comparative Example 2 does not occur. Is larger, and Example 1 is better in terms of astigmatism.

(Example 5)
The setting conditions of the spectacle lens of Example 5 are as follows. In Example 5, the aspherical sag is given only to the back surface side of the second lens element.
First lens element Front curve 2, back curve 2 (1.523 conversion)
Alvarez coefficient (A) 0.00025
Second lens element Front curve 2, back curve 4 (1.523 equivalent)
Alvarez coefficient (A) 0.00025
ASc (aspheric coefficient) = 4 × 10 ⁻⁹
ASd (aspheric coefficient) = 1.5 × 10 ⁻⁸
ASe (aspheric coefficient) = 1.5 × 10 ⁻⁹
ASf (aspheric coefficient) = 6.0 × 10 ⁻¹⁴

In the fifth embodiment, 1) a reference position, 2) both lens elements are moved in the opposite directions by equal distances (hereinafter both moved), and 3) the second lens element is fixed (hereinafter fixed back). We examined the distance vision state at the position.
FIG. 7 is a distribution diagram based on the average power in the distance vision state at the reference position and the numerical value of astigmatism. In this state, the S frequency was −4.00 D and the prism amount was 0. FIG. 8 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which each lens element is moved 6.70 mm in the horizontal direction. In this state, the S frequency was -2.00 D, and the prism was 0.02 on the in side. FIG. 9 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which only the first lens element is moved 13.30 mm in the horizontal direction. In this state, the S frequency was −2.00 D, and the prism was 1.34 on the in side.

(Example 6)
In the sixth embodiment, the Alvarez coefficient (A) of the first and second lens elements is set to 0.00025 (that is, twice that of the fifth embodiment) in the setting conditions of the fifth embodiment. Are the same. In Example 6, the distance vision state at each of 1) the reference position, 2) both movements, and 3) the back fixed position was examined.
FIG. 10 is a distribution diagram based on the average power in the distance vision state at the reference position and the numerical value of astigmatism. In this state, the S frequency was −4.00 D and the prism amount was 0. FIG. 11 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which each lens element is moved by 3.27 mm in the horizontal direction. In this state, the S frequency was −2.00 D, and the prism amount was 0. FIG. 12 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which only the first lens element is moved 6.60 mm in the horizontal direction. In this state, the S frequency was -2.00 D, and the prism was 0.66 on the in side.
Here, the movement amount in the sixth embodiment is half that of the fifth embodiment because the Alvarez coefficient is twice that of the fifth embodiment so that the lens power is the same as that in the fifth embodiment (here, -2D). This is because the amount of movement may be half. That is, here, if the movement amount is to be reduced, it can be realized by relatively increasing the Alvarez coefficient. In this case, since the movement amount is small, the prism amount is also reduced. However, increasing the Alvarez coefficient is disadvantageous in terms of astigmatism.

(Comparative Example 3)
In the third comparative example, the first lens element and the second lens element are not subjected to the aspheric process with the same curve size, Alvarez coefficient, and aspheric coefficient as those in the fifth embodiment.
Also in Comparative Example 3, the distance vision state at each of 1) the reference position, 2) both movements, and 3) the back fixed position was examined.
FIG. 13 is a distribution diagram based on the average power in the distance vision state at the reference position and the numerical value of astigmatism. In this state, the S frequency was −4.00 D and the prism amount was 0. FIG. 14 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which each lens element is moved 6.60 mm in the horizontal direction. In this state, the S frequency was -2.00 D and the prism amount was 0. FIG. 15 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which only the first lens element is moved 13.30 mm in the horizontal direction. In this state, the S frequency was −2.00 D, and the prism was 1.34 on the in side.

(Comparative Example 4)
In Comparative Example 4, the first lens element and the second lens element are not subjected to aspherical processing with the same curve size, Alvarez coefficient, and aspherical coefficient as in Example 6 as setting conditions.
In Comparative Example 4, the distance vision state at each of 1) the reference position, 2) both movements, and 3) the back fixed position was examined.
FIG. 16 is a distribution diagram based on the average power in the distance vision state at the reference position and the numerical value of astigmatism. In this state, the S frequency was −4.00 D and the prism amount was 0. FIG. 17 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which each lens element is moved 3.30 mm in the horizontal direction. In this state, the S frequency was -2.00 D and the prism amount was 0. FIG. 18 is a distribution diagram based on the average power and astigmatism values in the distance vision state in which only the first lens element is moved 6.50 mm in the horizontal direction. In this state, the S frequency was -2.00 D, and the prism was 0.66 on the in side.

(Contrast of Examples 5 and 6 and Comparative Examples 3 and 4)
From the viewpoint of astigmatism, the fifth embodiment having a corresponding relationship is clearly better than the fifth embodiment in which the aspherical processing is clearly performed. Similarly, the sixth embodiment, which has a corresponding relationship, is better than the sixth embodiment, which is clearly aspherical even with the fourth comparative example.
On the other hand, when Example 5 and 6 and Comparative Example 3 and 4 are examined as a whole, Example 6 with a small amount of movement has little aberration, and when moved, the best result is when the back is fixed in Example 6. there were.

It should be noted that the present invention can be modified and embodied as follows.
In the above-described embodiments, the simulation is performed in the case where there is no astigmatism power. However, when the astigmatism power is set, it is preferable to set the second lens element side in order to reduce astigmatism.
The above is an example of the sag function of the cubic surface and the aspherical sag function of the above embodiment, and other function expressions can be freely used.
An aspherical sag may be given only to the first lens element, or an aspherical sag may be given to both the first lens element and the second lens element.
The down prism may be increased when the lens element is moved from the distance power state to the near power state. At this time, the direction in which the lens element is moved is the vertical direction. Further, both the in-prism and the down-prism may be increased. At this time, the direction in which the lens element is moved is an oblique direction.
In addition, you may make it implement this Embodiment in another aspect.

Claims

The first and second lens elements can be arranged in parallel in the front-rear direction so that the optical axes are parallel, and moved in the opposite direction in a direction approximately orthogonal to the optical axis to change the S frequency. In the spectacle lens,
A partial derivative g obtained by partial differentiation with respect to x and y on the object side surface of the first lens element arranged on the outer side and the eyeball side surface of the second lens element arranged on the inner side, respectively. A function g (x, y) of the same or different curved surface such that xy is represented by a function or constant only of y is synthesized as an additional sag amount, and both lens elements are relatively opposite only in the x-axis direction. An eyeglass lens characterized in that it is movable, and at least one surface of both lens elements is aspherical to reduce aberrations.
The spectacle lens according to claim 1, wherein a function g (x, y) of a cubic curved surface synthesized as an additional sag amount in the first and second lens elements is defined by the following equation.
The spectacles according to claim 1 or 2, wherein a surface serving as a reference for synthesizing the additional sag amount with the first and second lens elements is any one of a spherical surface, a flat surface, and an astigmatic surface. lens.
The spectacle lens according to any one of claims 1 to 3, wherein the variable range of the S power is within 4 diopters.
The spectacle lens according to any one of claims 1 to 4, wherein one of the first and second lens elements is fixed and only the other is movable.
The spectacle lens according to claim 5, wherein the aspherical design is performed only on the lens element on the fixing side among the first and second lens elements.
7. The spectacle lens according to claim 5, wherein the astigmatism correction design is performed only on the lens element on the fixing side among the first and second lens elements.
The second lens element is fixed, only the first lens element is movable, and the refracting power relating to the light transmitted through the first and second lens elements is shifted to the plus side. The spectacle lens according to any one of claims 5 to 7, wherein the prism change caused by the movement of the first or second lens element is an increase in in-prism or a decrease in out-prism.
The spectacle lens according to claim 5, wherein the second lens element side is fixed and only the first lens element side is movable.
Peripheral glasses equipped with the spectacle lens according to any one of claims 1 to 9.