JPH03121412A - Progressive focus lens - Google Patents

Abstract

PURPOSE:To decrease the swaying and distorting of images over the entire part of respective regions by forming the progressive focus lens which is 0 diopter in far vision diopter and A diopter in penetration rate and has a specific face shape. CONSTITUTION:Equation I is defined by representing the unit vector of the incident rays on the progressive focus lens as L(theta1', theta2') by the polar coordinate designation, the coordinate center of which is the swiveling center of the eyeball and by similarly expressing the unit vector of the rays emitted from the lens as L'(theta1'', theta2'') with respect to the rays which are emitted from the eyes part the swiveling center of the eyeball, are made incident to the progressive focus lens and are emitted from this lens. The lens is constituted by having the face shape satisfying equations II to IV when the absolute values of the max. values of tantheta1, tantheta2 of the spherical lens corresponding to the A diopter as SAtheta1, SAtheta2. The swaying and distorting of the images over the entire part of the respective regions for the far vision part, intermediate part and near vision part are decreased in this way and the comfortable progressive focus lens is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a progressive lens for use as an aid to accommodative power of the eye.

[Conventional technology]

The upper distance vision correction area (
There are various progressive multifocal lenses that have a lower near vision correction area (hereinafter referred to as a distance vision area), a lower near vision correction area (hereinafter referred to as a near vision area), and a progressive area in which the refractive power changes continuously between the two (hereinafter referred to as an intermediate area). Are known.

In a progressive multifocal lens, generally, if a wide clear vision area is secured between the distance and near vision areas and a progressive zone is connected between them, lens aberrations will be concentrated in the side areas of the progressive zone.
The presence of this area causes image distortion, including blurring of the image, and gives a bad impression to the wearer as it sways when the line of sight moves.

In order to solve such problems in visual characteristics, known progressive multifocal lenses have been designed and evaluated from various viewpoints. The problem of image shaking and distortion depends on how the shape of the surface is formed. Conventionally, there have been efforts to alleviate this situation, such as the
3595, Japanese Patent Publication No. 52-20271, etc. are known. These were proposed for the purpose of improving static vision and dynamic vision, and are considered to correspond to the shaking and distortion referred to in the present invention.

[Problem to be solved by the invention]

In these conventional configurations, it is certainly possible to secure a somewhat wide clear vision range, but the distribution of astigmatism that is inevitable in progressive multifocal lenses, that is, the maximum amount of aberration called astigmatism and its gradient. It is difficult to obtain excellent visual characteristics across the three regions of distance, intermediate, and near vision by reducing the value of It has been extremely difficult to realize a progressive multifocal lens with excellent performance. Moreover, the methods for improving visual characteristics were a matter of groping, with no clear design methods, and no specific standards for evaluating performance.

In other words, in the past, cross-sectional shapes and longitudinal cross-sectional shapes have been described, but in each case only one of the cross-sectional shapes has been described, and this alone is insufficient to obtain the effects mentioned in the conventional examples. (It was impossible to explain.

When considering wobbling and distortion, it is clear that not only the amount of prism but also astigmatism and the like must be taken into account, and the amount cannot be determined just by describing one cross-sectional shape.

In addition, all of the conventional examples are based only on differential geometrical grounds and have the problem of being difficult to correspond to evaluations based on actual wearing conditions. I don't think it has been done. In other words, we will discuss the refractive power (average refractive power) and astigmatism (principal refractive power difference) of the first surface, which is an aspherical surface. There was only a very mathematical consideration of how to configure the shape of the device, and there was a lack of physical consideration of the state in which it would actually be worn by a human.

The purpose of the present invention is to evaluate the image shaking and distortion in the actual wearing condition, and to reduce the image shaking and distortion throughout the distance, intermediate, and near vision areas of this type of lens. To provide a progressive multifocal lens that can be worn comfortably even by a person using it for the first time.

[Means to solve problems]

The present invention has a distance portion F in the upper region of the lens, a near portion in the lower region, and an intermediate portion P between them, which refracts distance refractive power from the distance refractive power to the lower region. In a progressive multifocal lens as shown in Fig. 1, which has a progressive zone in which the average surface refractive power changes continuously, evaluate the image fluctuation and distortion under actual wearing conditions, and reflect this in the design. We have discovered that it is possible to quantitatively understand lens aberrations with respect to the shape of the entire surface, and have established a guideline for designing and evaluating progressive focus lenses from this new perspective.

That is, when the progressive focus lens is worn, light passes through the center of rotation of the eyeball and enters the progressive focus lens, and the unit vector of the light ray that enters the progressive focus lens is Expressed as L (θ1', θ, °) using polar coordinates with the center of eyeball rotation as the coordinate center,
Similarly, the unit vector of the light ray exiting the lens is L'
(θ1”, θ, #), tanθ, = tanθ, e-tanθ, 1tanθ, =
It is defined as tanθ2"-tanθ2"ε=ε"-ε, and t in a spherical lens equivalent to A diopter
The absolute value of the maximum value of anθl and tanθ is S^.

When 1.5 Aet, S /V + < janθl < S/V + S7v! <
tanθ2<5AfN −1,5A<e<1.5 A (degree)
The structure has a surface shape that satisfies the conditions (1), (2), and (3).

[For production]

The operation of the present invention as described above will be explained. Figure 2 shows
It shows an optical system when a lens is actually worn by a human being, and shows the configuration that is the premise of the design method according to the present invention. A wearer of a lens L visually recognizes an object by the light rays that enter the eye E through the lens L forming an image on the fundus of the eye.In the design method of the present invention, the fundus of the eye The evaluation is performed assuming that a light ray emitted from the side exits the lens L and forms an image on the object. As shown in the figure, light passing through the eyeball rotation center O of the eye E enters the lens L, undergoes a predetermined refraction, and exits.

Here, the difference Δα; α−α between the incident angle (α) of the light incident on the lens L and the output angle (α°) of the light coming out from the lens will be referred to as "ray deflection".

FIG. 3 shows an explanatory diagram of the design method according to the present invention. Although only the negative surface is shown for convenience of drawing, in practice it is considered as a combination of two lens surfaces of a progressive focal lens. 0. is the geometric center of the lens, and σ is the lens surface.

The unit vector of a ray of light that enters the lens surface through the center of eyeball rotation O is expressed as L (θ1゛, 62') in polar coordinates with the center of eyeball rotation as the center of coordinates, and the unit vector of the light ray that exits the lens is expressed as L(θ1゛, 62'). Similarly, L'(θ1'', θ
2”).

In this case, the “ray deflection” is each component, θ1 = θ1”-θ8゜ θ,=θ,”−θ,.

become. Here, each tangent
If we take and evaluate, tanθ,=tanθ,”−tanθ1jan θg=
Jan θ! ” tan θ1.

Further, the change due to refraction of the incident ray and the exit ray, that is, the change ε in the direction of the vectors L and L' is as follows.

Using the above parameters, it is possible to evaluate image shaking and distortion under actual wearing conditions. It is possible to reduce image shaking and distortion.

In addition, the number between 0 and 06 is generally 25III for Japanese people.
11. For Westerners, the distance is 28 mm, but this difference in distance is not an essential difference.

〔Example〕

The design method of the present invention as described above will first be explained using a general single focus lens as an example.

When the power of the distance part is 0 diopter, that is, when the spherical power is 0 diopter, the entire surface tanθ1, tanθ3
, ε are both almost zero. In addition, when the distance portion has power (has refractive power), if the absolute value of the maximum value of tanθ11tanθ2 of an A diopter spherical lens is S^19+, 5AD2, then 5AIII,
Both S^θ and (since it is a spherical surface, S^θ1=S80) are no longer zero. Furthermore, since both the first and second surfaces are spherical, only ε becomes zero. Furthermore, the sign (direction) is reversed in the case of positive and negative powers. Also,
In the case of an astigmatic lens, at least one surface is not spherical and the refractive power is different in two directions, so tanθ1, ta
The absolute values of the maximum values of nθ2 are not equal, and ε is no longer zero.

Since .theta.1 and .theta. are related to the amount of prism in the spectacle lens, they can be said to mainly relate to distortion that corresponds to image shaking. Since ε is a value indicating a change in the direction of the vector L1L', ε is related to the amount of image distortion. This ε can be called the so-called direction of distortion, or it can also be called the directional component of magnification change in distortion aberration. Also, the astigmatism is θ1, θ2 mentioned above.
, although not uniquely related to ε. In particular, when there is astigmatism, ε is no longer zero.

Based on this point of view, by designing a progressive focus lens to satisfy the conditions (1), (2), and (3) above, the progressive zone can be made to a practical length while reducing distortion and aberration. Astigmatism can be optimized, and image shaking and distortion can be reduced.

By applying the above-mentioned ray tracing concept, it is possible to evaluate even when the distance dioptric power is not 0.

In the case of general progressive focus lenses, the back surface is processed to provide prescriptions for distance vision, astigmatism, etc. At that time, the above (1) (2)
) and (3), when a distance diopter is prescribed, the absolute value of the maximum value of tanθ1s tanθ, by a spherical lens corresponding to the distance diopter (B diopter) is calculated as the above (1
) (2). At this time, equation (3) does not change for the reason described above. In other words, when the distance portion has B diopter as the desired refractive power, the above (
1) Instead of formula (2), the absolute value of the maximum value of tanθ1 and tanθ2 by a spherical lens equivalent to B diopter is S
, θl, slθ, then SAl? l S1u+ <tanθlku5A111
+Sllθ1 -8/Vt 5IHlt <θ, kuS^θ snow +Sly! −1,5A<e<1.5A (degree)
It is effective to have a shape that satisfies the following conditions.

By the way, when an astigmatic prescription is given, the absolute value of the maximum value of tanθr and tanθ2 of the spherical lens corresponding to the astigmatic power is added to the above equations (1) and (2). Furthermore, it is necessary to obtain ε due to the astigmatic lens in this case and add it to equation (3). Furthermore, the same concept can be applied to lenses to which prisms are added. Therefore, when the distance portion has an astigmatic power of C diopter, the absolute value of the maximum value of tanθ8 and tanθ by a spherical lens equivalent to C diopter is Scθ.

, 5cot, when the maximum value of ε due to an astigmatic lens equivalent to C diopter is X, SAe+ sl#l SC#I < tanθl
kuS〜+ +Sssθ+ +Sce+ S＾ez 5ill! 5cot <tanθ, kuS^e* +S+u2+5cst -1,5A-X< e <1.5 A+X (degr
It is effective to have a shape that satisfies the condition ee).

It can be seen that an extremely simple relationship holds when a distance prescription or an astigmatism prescription is made in this way.

As can be seen from the fact that prescriptions for distance vision and astigmatism are made by processing the back surface, it is important to satisfy the above conditional expression. In other words, it is sufficient to provide a surface shape that satisfies this conditional expression.

FIG. 4 is a diagram showing the isoastigmatism difference curve for the embodiment as described above, and FIG. 5 is a diagram showing an outline of the isastigmatism curve in a conventional progressive multifocal lens for comparison.

Conventional progressive multifocal lenses are not configured to satisfy the above conditions according to the present invention.
As shown in the figure, the density of the astigmatism difference becomes high, and the amount of astigmatism difference and the gradient of the astigmatism difference become steep.As a result, the distortion of the image increases, and when you move your line of sight, you feel the image shake. I will do it. In addition, the astigmatism aberration from the lateral region of the intermediate portion seeps into the lateral region of the distance vision force, and when the eye is directed to this region, not only the image is blurred, but also the image is blurred. Distortion and shaking have become noticeable.

In contrast, in this example, as shown in FIG. 4, the density of the astigmatism difference in surface refractive power is reduced, the gradient of the astigmatism difference is also gentle, and image distortion and shaking are reduced. is clear.

The numerical values of the embodiment according to the present invention shown in FIG. 4 will be explained. The progressive focus lens as an example has a distance power of 0
It has specifications of a diopter addition of 2.5 diopters and a progressive band length of 14 mm. As shown in FIG. 4 (because it is bilaterally symmetrical, only the values on the right half are shown. FIG. 6 shows tan θ1 in the progressive lens of the example, and FIG. The figure is a diagram showing the value of ε in the progressive focus lens of the example.

In each figure, the vertical axis is tanθ1°, corresponding to the coordinate system shown in FIG. 3, and the horizontal axis is tanθ.

It is. The lens diameter is 75 mm, and the distance to the rotation point of the eye is 25 m on both the vertical and horizontal axes, as shown in Figure 3.
Using m, the position on the lens surface is shown as a tangent value, which corresponds to the distance on the lens surface as follows.

'tanθ2±1.5-+ 37.5mm'tanθ2
±1.0->25.0mm'tanθ2±0.5-+
12.5mm'tanθ20.0→0. Omm Further, FIG. 9 shows tan θ8 for the spherical lens corresponding to the addition power in the progressive focal lens of the example, and tan θ8 for the spherical lens corresponding to the addition power in the progressive focal lens of the example in FIG. 1 θ.

, FIG. 11 shows the value of ε for a spherical lens corresponding to the addition power in the progressive focus lens of the example.

Here, the value of tanθ shown in FIG. 6 is 0.31', the absolute value of the maximum value of tanθ1 for the addition equivalent spherical lens in the effective area shown in FIG. It can be seen that the value is always smaller than .

Similarly, from a comparison between FIG. 7 and FIG. 10, the value of tanθ shown in FIG. 7 is the maximum of tanθ for the addition equivalent spherical lens in the effective area shown in FIG. The value is always smaller than the absolute value of 0.317. Furthermore, as shown in Fig. 11, it is natural that the values of ε are all 0 since it is a spherical surface, and it is clear that the value of ε shown in Fig. 8 satisfies the above formula (3). be.

In addition, since eyeglass lenses are generally circular, the numbers at the top and bottom of the right end of the numbers shown in each figure are written to make it easier to understand the surface shape, and in the actual lens,
The area within the bold line in each figure is a meaningless area.

〔Effect of the invention〕

According to the present invention as described above, since the evaluation is performed in the actual wearing condition, it is possible to reduce the astigmatism difference over the entire refractive surface of the lens in the wearing condition, and the maximum value of the astigmatism difference is also small. , and its slope becomes gentler. Therefore, the aberration density is not only alleviated in the aberration concentration area on the side part of the principal meridian curve from the distance lower power to the near vision, but also throughout the distance, intermediate, and near vision regions. Image shaking and distortion can be reduced, making it possible to provide an extremely comfortable progressive focus lens. Furthermore, the present invention is useful as a standard for specific performance evaluation.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an outline of the area division of the progressive focus lens of the present invention, Fig. 2 is an explanatory diagram of the optical system when a human actually wears the lens, and Fig. 3 is a plan view of the design of the present invention. An explanatory diagram of the method, FIG. 4 is an isoastigmatism difference curve diagram for an example according to the present invention, FIG. 5 is an isastigmatism difference curve diagram for a conventional progressive multifocal lens, and FIG. 6 is an isoastigmatism difference curve diagram for an example of the present invention. Fig. 7 shows the value of tan θ8 in the progressive lens of the example, Fig. 8 shows the value of ε in the progressive lens of the example, and Fig. 9 shows the value of ε in the progressive lens of the example. tan θ1 for the spherical lens corresponding to the addition power in FIG. 10, tan θ2 for the spherical lens corresponding to the addition power in the progressive focus lens of the example, and FIG. is the value of ε for a spherical lens. F...Distance part P...Intermediate part N...Near part [Explanation of symbols of main parts] 0,...Distance center ON...Near center E...Distance eye point

Claims (1)

[Scope of Claims] 1) A distance part having a refractive power corresponding to a distant view along a principal meridian curve, a near part having a refractive power corresponding to a near view, and the distance part and the near part. A progressive focus lens having an intermediate part that continuously and smoothly connects the refractive powers of both parts, wherein the distance power of the progressive focus lens is 0 diopter and the addition power is A diopter; When the lens is worn, light passing through the eyeball rotation center enters the progressive focus lens, and for the outgoing light ray, the unit vector of the light ray that enters the progressive focus lens is coordinated with the eyeball rotation center. Expressed as L(θ_1', θ_2') in polar coordinates with the center at the center, the unit vector of the light ray exiting the lens is similarly expressed as L'(θ_1'', θ
_2"), tanθ_1=tanθ_1"-tanθ_1'tan
θ_2=tanθ_2"-tanθ_2'▲There are mathematical formulas, chemical formulas, tables, etc.▼, and t in a spherical lens equivalent to A diopter is defined as
The absolute value of the maximum value of anθ_1 and tanθ_2 is S_A_
When θ_1 and S_A_θ_2, −S_A_θ_1<tanθ_1<S_A_θ_1−S
_A_θ_2<tanθ_2<S_A_θ_2-1.5
A progressive focus lens having a surface shape that satisfies the condition A<ε<1.5A (degree). 2) A distance part having a refractive power corresponding to a distant view along the principal meridian curve, a near part having a refractive power corresponding to a near view, and refraction of both parts between the distance part and the near part. A progressive-focus lens having an intermediate portion that connects forces continuously and smoothly, wherein the distance power of the progressive-focus lens is B diopter and the addition power is A diopter, and when the progressive-focus lens is worn, Outgoing light from the eye passes through the eyeball rotation center and enters the progressive focus lens, and for the outgoing light ray, the unit vector of the light ray that enters the progressive focus lens is expressed in polar coordinates with the eyeball rotation center as the coordinate center. Expressed as L(θ_1', θ_2'), the unit vector of the light ray exiting the lens is similarly expressed as L'(θ_1'', θ
_2"), tanθ_1=tanθ_1"-tanθ_1'tan
θ_2=tanθ_2"-tanθ_2'ε=ε"-ε
' ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Defined as t for a spherical lens equivalent to A diopter.
The absolute value of the maximum value of anθ_1 and tanθ_2 is S_A_
θ_1, S_A_θ_2, and the absolute value of the maximum value of θ_1 and θ_2 by a spherical lens equivalent to B diopter is S_
When B_θ_1, S_B_θ_2, −S_A_θ_1−S_B_θ_1<tanθ_1<S
_A_θ_1+S_B_θ_1 −S_A_θ_2−S_B_θ_2<tanθ_2<S
_A_θ_2+S_B_θ_2 -1.5A<ε<1.5A (degree) A progressive focal lens having a surface shape that satisfies the condition: _A_θ_2+S_B_θ_2 -1.5A<ε<1.5A (degree). 3) A distance part having a refractive power corresponding to a distant view along the principal meridian curve, a near part having a refractive power corresponding to a near view, and refraction of both parts between the distance part and the near part. a progressive-focus lens having an intermediate portion that connects forces continuously and smoothly, the progressive-focus lens having a distance power of B diopters, an addition power of A diopters, and an astigmatic power of C diopters; When the progressive focus lens is worn, light passing through the center of eyeball rotation and exiting from the eye enters the progressive focus lens, and the unit vector of the light ray that enters the progressive focus lens is used to rotate the eyeball. L(θ_1',
Similarly, the unit vector of the light ray exiting the lens is L'(θ_1", θ_2"), and tanθ_1=tanθ_1"-tanθ_1'tan
θ_2=tanθ_2"-tanθ_2'ε=ε"-ε
' ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Defined as t for a spherical lens equivalent to A diopter.
The absolute value of the maximum value of anθ_1 and tanθ_2 is S_A_
θ_1, S_A_θ_2, the absolute value of the maximum value of θ_1, θ_2 by a spherical lens equivalent to B diopter is S_B_
θ_1 and S_A_θ_2, and the absolute value of the maximum value of θ_1 and θ_2 with an astigmatic lens equivalent to C diopter is S
_C_θ_1, S_C_θ_2, When the maximum value of ε due to an astigmatic lens equivalent to C diopter is X, −S_A_θ_1−S_B_θ_1−S_C_θ_1<
tanθ_1<S_A_θ_1+S_B_θ_1+S_
C_θ_1-S_A_θ_2-S_B_θ_2-S_C
_θ_2<tanθ_2<S_A_θ_2+S_B_θ
_2+S_C_θ_2-1.5A-X<ε<1.5A+
A progressive focal lens characterized by having a surface shape that satisfies the condition of X (degree).