JP2012215641A - Spectacle lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectacle lens with comfortable wearing feeling.SOLUTION: In a spectacle lens, at least one of an object side surface and an eyeball side surface is a free-form surface excluding a spherical surface, and the free-form surface is subjected to a slab-off process.

Description

  The present invention relates to a spectacle lens, and more particularly to a spectacle lens in which the prism action is adjusted to improve the wearing feeling.

  The multifocal spectacle lens includes a distance portion having a distance power for far vision and a near portion having a near power for near vision. Among these multifocal spectacle lenses, a progressive-power lens having a progressive surface whose refractive power continuously changes from the upper part to the lower part, the refractive power continuously changes between the distance portion and the near portion. Intermediate part. Among progressive-power lenses, a double-sided aspherical progressive-power lens developed in recent years is a spectacle lens that functions as a bifocal lens by progressive elements distributed on both surfaces of the lens.

Generally, in spectacle lens prescriptions, in addition to the above-mentioned refractive power related to the focal effect such as the distance power and the near power, there is a prism power that changes the direction of the line of sight. To do. When manufacturing a multifocal spectacle lens, when determining the refractive power of the distance portion, the refractive power of the near portion is determined by the shape of the progressive surface, the distance portion's refractive power and the addition power, and for the same reason. If the prism refractive power of the near portion is determined, the prism refractive power of the distance portion is determined. Accordingly, it is difficult to freely select the refractive powers of the distance portion and the near portion.
However, as described in Patent Document 1 and the like, most spectacle wearers do not have the same visual acuity. Accordingly, if the prism amounts of the left and right lenses are matched in one of the distance portion and the near portion, a difference occurs in the prism amounts of the left and right lenses on the other side. This is called prism error, and there is a large difference in power between the left and right, so the glasses error for so-called non-sighted wearers causes the prism error to become extremely large, causing eyestrain and headaches. If the deviation of the light incident on the human exceeds the limit that the human brain can image, a double image is formed, causing the symptom of double vision.

WO2009 / 072528

  Therefore, an object of the present invention is to provide a spectacle lens having a comfortable wearing feeling.

The above object of the present invention is to
An eyeglass lens, wherein at least one of the object side surface and the eyeball side surface is a free curved surface excluding a spherical surface, and the free curved surface is subjected to slab-off processing,
Achieved by.

Below, the conventional slab-off process is demonstrated.
The slab-off process is a process of cutting a part of the lens surface in order to adjust the prism action of the lens, and the amount of prism can be reduced by cutting. Hereinafter, a general slab-off process will be described with reference to FIG.
FIG. 9 is an explanatory diagram of a process of performing slab-off processing on the optical surface of a bifocal lens (semi-finished lens). The lens to be processed shown in FIG. 9A is a bifocal lens in which a small lens is embedded in a ball lens, and a near portion is formed by the small lens. In the bifocal lens having such a configuration, in the case of near vision, a region about 8 to 10 mm below the optical center of the ball lens is used, and a prism is generated in the near portion due to the strength of the lens power. . If the power difference between the left and right lenses is 1.00D or less, the prism is also within 1Δ, and the wearing feeling is not impaired when viewing with both eyes, but if the difference is 1.5D or more, the left and right imbalance due to the prism is significant. It becomes. In this case, by removing at least a part of the left or right lens (slab-off processing), the prism action of the left and right lenses can be adjusted to improve the wearing feeling during binocular vision. Specifically, as shown in FIG. 9B, a dummy lens having a surface shape obtained by transferring the shape of the processing surface is bonded to the processing surface. Next, as shown in FIG. 9C, the region to be removed (slab-off processing region) is removed by machining such as grinding together with the dummy lens. FIG. 9 shows an example of processing a semi-finished lens, but machining (grinding or cutting, and subsequent polishing) that creates an optical surface on the non-optical surface (concave surface in FIG. 9) of the semi-finished lens. Is usually performed before removing the dummy lens remaining after the slab-off processing. The lens with the optical surface thus created is in the state shown in FIG. 9D, and a spectacle lens (FIG. 9E) subjected to slab-off processing is obtained by removing the dummy lens from the lens in this state.

  In the conventional slab-off processing described above, for example, when the surface to be processed is a convex surface, a dummy lens having a surface-shaped concave surface to which the shape of the convex surface is transferred is produced, and the concave surface of the dummy lens is formed as a surface to be processed (convex surface ). If the surface to be processed is a spherical surface, it is easy to form a surface shape obtained by transferring the surface (that is, a spherical surface) on the dummy lens. However, since it is difficult to produce a dummy lens having a surface shape obtained by transferring the optical surface of a spectacle lens having an optical surface having a complicated shape with different curvatures in the surface like a progressive power lens, In the method, the surface to be slab-off processed is limited to a spherical surface. In Patent Document 1, it is described that it is possible to perform a slab-off process on a progressive-power lens. This is because the spherical surface on the eyeball side of an outer-surface power lens in which a progressive surface is arranged on the object side, and the like. This means that slab-off processing is performed on the spherical surface on the object side of the internal refractive lens in which a progressive surface is arranged on the eyeball side. Among the multifocal spectacle lenses, the plastic bifocal lens has a near portion and a far portion by projecting small balls on the convex side (object side), so it slabs off on the convex side from which the small balls project. Processing has not been performed conventionally, and the prism action has been adjusted by performing slab-off processing on the concave surface which is a spherical surface.

  On the other hand, as a result of intensive studies, the present inventors have found that the progressive surface of the outer surface or the inner surface refractive power lens, the surface including the progressive element of the double-sided aspherical progressive power lens, and the plastic bifocal lens described above As a result, the present inventors have completed the present invention by finding means capable of performing slab-off processing on a free-form surface shape excluding a spherical surface, which has been difficult to perform slab-off processing by a conventional method such as a convex surface. In other words, a spectacle lens obtained by subjecting a free curved surface other than a spherical surface to slab-off processing is provided for the first time by the present invention.

  According to the present invention, a spectacle lens having a very comfortable wearing feeling can be provided.

It is a figure showing the cross section of a progressive-power plastic lens. It is a figure showing the cross section of an aspherical refractive power plastic lens symmetrical about a center. It is a figure showing the cross section of a progressive-power glass lens. It is S frequency (average power) distribution map of a progressive multifocal lens. It is C power (cylinder power) distribution map of a progressive multifocal lens. It is a bird's-eye view corresponding to S frequency distribution of FIG. It is a bird's-eye view corresponding to C frequency distribution of FIG. It is explanatory drawing of a slab-off process area | region. The specific example of the cross-sectional shape of a plastic bifocal lens is shown. It is a figure which shows the position of the optical center of the near part of the bifocal lens shown to Fig.7 (a)-(c). It is explanatory drawing of the conventional slab-off process.

  The eyeglass lens of the present invention is characterized in that at least one of the object-side surface and the eyeball-side surface is a free-form surface excluding a spherical surface, and the free-form surface is subjected to slab-off processing. Here, the slab-off process means that a part of the surface of the spectacle lens is cut by machining to adjust the prism action as described above. The slab-off process can be easily confirmed by the presence of a boundary line between the slab-off process area and the unprocessed area (hereinafter referred to as “slab offline”) or by measuring the prism refractive power.

  Even if the spectacle lens of the present invention is a finished lens that is a double-sided optical surface, one surface is an optical surface and the other surface is a non-optical surface. It may be a semi-finished lens in which an optical surface having the following optical characteristics is created. Further, the shape of the surface subjected to the slab-off process can be any shape such as a flat surface, a convex surface, or a concave surface. The material of the spectacle lens is not particularly limited, and examples thereof include various materials that are usually used as a material for spectacle lenses such as plastic and inorganic glass.

In the spectacle lens of the present invention, the surface on which the slab-off processing is performed is a free-form surface excluding a spherical surface that has been difficult to perform in the conventional slab-off processing. The free-form surface excluding the spherical surface is a surface having a surface shape constituted by surfaces having different curvatures at the distance measurement position on the optical surface and curvatures at other positions. For example, an axisymmetric aspherical refractive power lens And optical surfaces such as progressive-power lenses and double-sided aspherical progressive-power lenses. Moreover, the convex surface which has the protrusion part of the above-mentioned plastic bifocal lens is also contained.
On the other hand, the spherical surface is a surface having a surface shape with a constant curvature at other positions on the distance measurement unit and the lens optical surface. On the other hand, the axisymmetric aspherical shape is a shape in which, for example, the curvature at the distance measurement position arranged at the geometric center is different from the curvature at other positions on the lens optical surface. In general, an axially symmetric aspherical lens has a distance measuring portion arranged at the geometric center, and has a shape in which the curvature continuously increases or decreases as the distance from the lens center increases on the principal meridian from the center to the lens periphery. A centrally symmetric aspheric lens has, for example, the cross section of FIG. The progressive power lens is a lens used as a presbyopic progressive power lens. Progressive-power lenses are generally used widely because they are presbyopic eyeglass lenses that are not easily perceived as presbyopia in appearance, and that they can be clearly visible continuously from long to short distances. ing. Multiple fields of view, such as a field of view for viewing a distance and a field of view for a near distance, and a field for viewing an intermediate distance between them are arranged without a boundary line in a limited lens area. Has been. The progressive power lens that can be processed according to the present invention includes, for example, a single-sided surface having a progressive surface on either the first refractive surface that is the object-side surface or the second refractive surface that is the eyeball-side surface ( The outer surface or the inner surface) progressive power lens, and secondly, the progressive power element is divided and distributed into the first refractive surface which is the object side surface and the second refractive surface which is the eyeball side surface. And a double-sided aspherical progressive-power lens having a configuration in which the first surface and the second surface are combined to give a distance power and an addition power based on a prescription value. The progressive power lens has, for example, the power distribution of FIGS. 2 to 5 or the cross sections of FIGS. 1a and 1c.

  As described above, since it was difficult to perform slab-off processing on the lens surface having the above shape in slab-off processing using a conventional dummy lens, slab-off processing was performed on a free-form surface other than a spherical surface. Conventionally, eyeglass lenses have not been known. On the other hand, the present inventors made it possible to perform slab-off processing on a free-form surface other than a spherical surface by performing slab-off processing without using a dummy lens. Hereinafter, a slab-off process suitable as a method for producing the spectacle lens of the present invention will be described with reference to the drawings.

  The left figure of FIG. 6 is a sectional view of a progressive-power lens (finished lens) having a convex surface on the object side and a concave surface on the eyeball side, and a near portion is disposed below the optical center. The right side of FIG. 6 is a plan view of the concave surface. In this concave surface, a region above the near portion (region above the solid line) is cut off by a predetermined amount by machining to reduce the longitudinal prism difference in distance vision. In this case, since the hatched portion in the right figure of FIG. 6 is a region to be an uncut region, the region is covered with a coating. The film may be formed by depositing an inorganic material or a metal material by a known film forming method such as vapor deposition or sputtering, or for forming a film by a known coating method such as a dip method, a spin coating method, or a spray coating method. You may form by apply | coating a coating liquid. For example, a film can be formed in a desired area by performing a film forming process on the entire surface of the lens in a state where an area to be uncoated is protected with a masking tape, and removing the masking tape after the process. From the viewpoint of ease of film formation, a coating method is preferably used. As the coating solution, a composition containing a thermosetting component or a photocurable component (curable composition) can be used, and a desired curing treatment (heating or light irradiation) is performed on the lens surface after coating. A cured film can be formed at the position. It is preferable to use a photocurable composition such as an ultraviolet curable composition because it can be cured in a short time. Such a curable composition can be prepared by a well-known method, and what is generally marketed as a hard coat coating material for spectacle lenses can be used without any limitation. Alternatively, a masking tape can be used as the coating. As the masking tape, a commercially available protective tape having an adhesive layer or an adhesive layer on one or both sides of the support film can be used. The thickness of the coating is not particularly limited and can be, for example, about 10 to 50 μm. The thickness of the coating can be controlled by the film forming conditions and the coating conditions. Moreover, in the aspect using said masking tape, you may laminate | stack several masking tapes as needed so that total thickness may become desired thickness.

On the other hand, a plastic bifocal lens usually has a distance portion and a near portion by providing a protrusion (near portion) on a part of at least one surface as described above. A specific example of the cross-sectional shape of such a bifocal lens is shown in FIG. 7A shows a positive refractive power for the distance portion and the near portion, FIG. 7B shows a negative refractive power for the distance portion, and a positive refractive power for the near portion. FIG. Both the distance portion and the near portion are negative refractive power lenses. In FIG. 7, A is the optical center of the distance portion, B is the geometric center of the near portion, and the optical centers of the near portion in each case are as shown in FIGS. , Move between A and B according to the refractive power difference (additional power) between the distance portion and the near portion at positions below B and above A.
When a slab-off process is performed on a convex surface partially having a protrusion in this manner by a conventional method, a concave portion that fits the protrusion is formed on the concave surface of the dummy lens. Since it is difficult to manufacture a surface-shaped dummy lens, conventionally, the surface on which slab-off processing is performed has to be concave. On the other hand, according to the present invention, for example, in the bifocal lens having the cross-sectional shape shown in FIGS. 7A to 7C, the lower region including the convex protrusions (in FIGS. 8A to 8C, The prism action can be adjusted in the region above the projecting portion of the convex surface by performing slab-off processing in a state where the region below the dotted line) is covered with a film and the region above the projecting portion is uncovered.

  As described above, by performing machining in a state where the region to be cut on the surface to be cut is uncovered and the region to be cut is covered with a film, regardless of the dummy lens, Slab-off processing can be performed.

  Machining for cutting off the uncoated region after forming the coating can be performed by grinding, cutting, or the like, as in a normal slab-off process. Here, the jig used for machining may contact the coating. Since it is protected by the coating, the region under the coating becomes an uncut region. In general slab-off processing, a region to be cut is ground or ground by a curve generator. Thereafter, the machined surface is mirror-polished to obtain a spectacle lens having an optical surface in which the prism action is adjusted. Since the polishing process is a process for eliminating the roughness due to the machining of the excision area subjected to the slab-off process, it is performed at least on the excision area. However, the polishing jig may be in contact with a portion other than the excision region. The polishing process may be performed with a film applied or after the film is removed. It is also possible to polish the entire surface by removing the coating after polishing with the coating applied. The removal of the film can be performed by a known method such as wiping with a solvent. Moreover, what is necessary is just to peel a tape from on a lens, when a masking tape is used as a film. Thereafter, for the semi-finished lens, a spectacle lens having both surfaces finished to optical surfaces can be obtained by performing processing for creating the other surface (non-optical surface) on the optical surface after slab-off processing. The removal of the coating in this case may be performed before the creation of the optical surface or after the creation.

  By the method described above, slab-off processing can be easily performed on the lens surface of various shapes, and thereby it is possible to provide a progressive power lens, a bifocal lens and the like having excellent wearing feeling.

  The present invention will be further described below with reference to examples. However, the present invention is not limited to the embodiment shown in the examples.

[Example 1]
A slab-off process was applied to the concave surface of a double-sided aspherical progressive-power lens (finished lens) having a convex surface on the object side and a concave surface on the eyeball side by the following procedure.
A curve generator that performs three-dimensional NC control after a commercially available protective tape (thickness: 10 μm) is attached to the entire surface of the concave optical center 3 mm below the concave optical center as shown in the right figure of FIG. 1 via an adhesive layer. A cutting process was performed. As a result, the area on the side of the distance portion that is not covered with the protective tape was spherically cut. After carrying out the mirror polishing after the cutting with the protective tape applied, the protective tape was peeled off.

[Example 2]
The same operation as in Example 1 was performed except that two protective tapes were laminated to form a film having a total thickness of 20 μm.

[Example 3]
The same operation as in Example 1 was performed except that three protective tapes were laminated to form a coating having a total thickness of 30 μm.

[Example 4]
A slab-off-processed spectacle lens was obtained by performing the same operation as in Example 1 except that a film was formed by the following method.
The protective tape used in Example 1 was attached to a region excluding a region 3 mm below the optical center of the concave surface of the spectacle lens. Next, after a commercially available acrylic UV curable resin was applied to the entire concave surface by a spin coating method so that the thickness after curing was about 10 μm, a UV curing treatment was performed to form a cured film. Thereafter, the masking tape was removed together with the cured film formed on the tape. As a result, a region 3 mm below the optical center could be covered with a cured film having a thickness of about 10 μm.

[Example 5]
The protective tape used in Example 1 is applied to the lower region (region below the dotted line in FIG. 8A) including the convex protrusion of the plastic bifocal lens having the cross-sectional shape shown in FIG. Thereafter, the same operation as in Example 1 was performed.

[Example 6]
The same operation as in Example 1 was performed on the concave surface of the inner surface progressive-power lens in which the object-side surface (convex surface) is a spherical surface and the eyeball-side surface (concave surface) is a progressive surface.

  About Examples 1-6, the prism refractive power in the distance part measurement reference point before and behind slab-off process was measured with the lens meter, and it was confirmed that prism refractive power fell by the slab-off process. In Examples 1-6, although the slab-off process was performed to either the object side surface or the eyeball side surface, the other surface can also be subjected to a slab-off process. In that case, slab-off processing may be performed on the spherical surface by a method using a conventional dummy lens. In Examples 1 to 4, since it is an aspherical surface including progressive elements on the object side surface as in the eyeball side, slab-off processing can be performed by the above-described method using a film.

  Further, in Examples 1 to 3, the film thickness of the coating was changed by changing the number of layers of the masking tape. However, the boundary line between the slab-off processed area and the unprocessed area (slab offline) becomes more visible as the film thickness increases. Visible clearly. This point will be described in detail. When the spectacle lenses obtained in Examples 1 to 3 were respectively worn under a fluorescent lamp, the spectacle lens of Example 1 was so incapable of confirming the presence of a slab offline from others at the time of wearing. The visibility of the slab offline was very low. On the other hand, in the spectacle lens obtained in Example 2, the other person could not confirm the presence of the slab offline at the time of wearing, but the slab offline to such an extent that the wearer could confirm the existence of the slab offline. Visibility increased. As for the spectacle lens obtained in Example 3, it was confirmed that both the wearer and others had a slab offline.

For the eyeglass lenses of Examples 1 to 3, the surface shape of the entire surface subjected to the slab-off process was measured using a stylus type (non-contact type using a probe) surface shape measuring instrument (trade name UA-3P manufactured by Panasonic Corporation). Measured. In addition, although the said surface shape measuring device was used here, surface shapes can also be measured using techniques, such as an atomic force microscope. In Examples 1 and 2, the surface subjected to slab-off processing can be approximated by a function that can be first-order differentiated based on the obtained measurement data, but in Example 3, it can be approximated by a curve and linearly approximated. There wasn't.
From the above results, it was shown that the spectacle lens having a surface shape in which the region including the slab offline can be first-order differentiated is a lens in which the slab offline is not easily visually recognized.
Moreover, since the primary differential value (gradient) obtained about Example 1 was 0.4 or less and the primary differential value (gradient) obtained about Example 2 was more than 0.4 and less than 0.7, It was confirmed that the level could be used as an indicator of slab offline visibility.
[Level 1] The primary differential value (gradient) of the surface shape measurement value measured using a stylus type (non-contact type probe) surface shape measuring instrument is 0.4 or less: the slab offline itself It is not visible to others.
[Level 2] The primary differential value (gradient) of the shape measurement value is more than 0.4 and less than 0.7: Although the slab offline is not visually recognized by others, it can be confirmed that the slab offline exists.
[Level 3] The primary differential value (gradient) of the shape measurement value is 0.7 or more: The visibility of the slab offline is higher than Level 2.
[Level 4] The shape measurement value cannot be first-order differentiated: The slab offline is easily visually recognized by itself and others.

  As described in Patent Document 1, the progressive-power lens has an advantage that the boundary between the distance portion and the near portion is not conspicuous. Therefore, it is usually not desirable that the boundary line (slab offline) between the region cut by the slab-off process and the uncut region is clearly visible. On the other hand, some wearers may prefer that the slab offline can be clearly seen. Because, if the slab offline can be clearly seen, the slab-off processed area can be easily identified, so by moving the line of sight with the slab offline as a mark, it is possible to immediately select an area where a good wearing feeling can be obtained within the lens surface. This is because it can. That is, it is desirable that the visibility of the slab offline generated by the slab-off process can be selected according to the wearer's preference. As demonstrated in Examples 1 to 3, according to the method found by the present inventors, the visibility of the slab offline can be controlled by the film thickness of the coating, so that according to the preference of the wearer. It is possible to provide a slab-off-processed lens having a good appearance.

  The present invention is useful in the field of manufacturing eyeglass lenses.

Claims (4)

An eyeglass lens, wherein at least one of the object side surface and the eyeball side surface is a free curved surface excluding a spherical surface, and the free curved surface is subjected to slab-off processing. The spectacle lens according to claim 1, wherein the free-form surface is a progressive surface or an aspherical surface including a progressive element. The spectacle lens according to claim 1, wherein a region including a boundary between the region subjected to the slab-off processing and the unprocessed region has a first-order differentiable surface shape. The spectacle lens according to claim 1, wherein the free-form surface is a convex surface having a protruding portion of a bifocal lens.

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