JP2008090204A - Lens for eyeglasses - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eyeglasses with good appearance that can suppress glare when they are put on, by applying coating that reduces aberrations and stray lights specific to a microprism array. <P>SOLUTION: The lens for eyeglasses have fine microprisms arranged on its inner surface or outer surface as high as or higher than the resolution of the human eyes, and the refractive power by the microlens is varied depending on the region , and a multilayer coating is applied to decrease the transmission of visible light, in a band around a wavelength of 400-430 nm and 555-600 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spectacle lens having a single focus and a progressive focus.

  Conventionally, a lens for spectacles has a power formed by a curve difference between the inner surface and the outer surface of the lens. A special lens, for example, a progressive focus lens, has one or both surfaces made aspherical or spherical to form the refractive power of the progressive portion with a curve difference between the front surface and the back surface. In order to form the progressive portion, a distorted region where frequency measurement cannot be performed is formed on the left and right sides of the progressive portion. In particular, when the addition power of the progressive part increases, the distortion tends to increase, and when the head is swung left and right, the scenery also seems to shake, even if this is uncomfortable for the wearer, when using a progressive focus lens, The wearer must get used to the distortion. Progressive focus lenses in recent years have made various design efforts to make this distortion difficult to perceive, but in progressive focus lenses that obtain the refractive index by the difference between the two curves on the front and back surfaces, the distortion is reduced. It cannot be lost.

As a conventional technique, there is a technique such as Patent Document 1 “MULTIPLE FOCAL LENGTH LENS” which attempts to obtain a plurality of focal positions by changing the refractive power of adjacent prisms in a Fresnel lens. In the method of alternately changing the refractive index of the upper prism, it is difficult to obtain a high resolution as an optical lens because there is a gap in the light refraction path in units of one focal point.
US Pat. No. 3,004,470

  In a conventional spectacle lens that obtains the refractive index by the difference between the two curves on the front and back surfaces, if a high power difference is provided, the thickness at the periphery or the center of the lens increases and the weight of the lens increases. End up. Although a lens material having a high refractive index can be reduced to some extent by selecting a lens material having a high refractive index, there is a tendency that the color dispersion tends to increase as the refractive index of the lens material generally increases, and there is a drawback that it is easy to feel color blur.

  In recent years, plastic materials called CR39 are often used as the main material for eyeglass lenses, but when using this material to mold a microprism array using the same production method as the microlens array, first mold And a method in which it is formed by slow cooling after injection molding or thermal polymerization. In this case, depending on various conditions such as the viscosity of the material, there is a case where the material is not sufficiently filled to every corner of the mold. In particular, the edge portion of the prism is very finely missing or rounded. Furthermore, when arranging fine prisms, there is a difference in height between adjacent prisms, and the bases of the prisms protrude from the apexes of the adjacent prisms. When external light enters such a part, it becomes reflected light or stray light, which may cause discomfort during wearing, and thus requires processing to make it difficult for the wearer to feel.

  The present invention solves the problem by arranging a large number of cell-formed microprisms molded by microfabrication on the front or back surface of a spectacle lens in an array and molding a spectacle lens as a microprism array.

  According to the first aspect of the present invention, in the spectacle lens, microprisms are arranged in an integrated manner on the inner surface or the outer surface with a fineness equivalent to or higher than the resolution of the human eye, and the microlens depending on the part. By changing the refracting power due to the above, a distortion-free spectacle lens is obtained.

  According to a second aspect of the present invention, in the spectacle lens according to the first aspect, light having an unpleasant wavelength such as aberration or stray light generated in a microprism is controlled by a multilayer coating. And a multilayer coating that reduces the transmittance of visible light in the wavelength range of 400 to 430 nm and in the vicinity of 555 to 600 nm.

  The function as an optical lens for spectacles is achieved by arranging microprisms on a lens-like material having curves on the inner and outer surfaces of an optical lens such as a meniscus lens. In manufacturing a single-focal lens for spectacles formed in this way, light is collected at one focal position by refraction of the prism on the front or back surface, and in manufacturing a progressive-focus spectacle lens, different refractive powers are used depending on the part. The microprisms are arranged in an integrated manner, and a spectacle lens is molded and manufactured to obtain a single-focus lens and a distortion-free spectacle progressive lens that can be used as spectacles. In addition, a function as a spectacle lens is achieved by applying a coating that transmits only a specific wavelength.

  Conventionally, in a spectacle lens, the power is obtained by the difference between the outer surface curve and the inner surface curve. However, according to this method, each minute microprism generates the same refractive power as that of the spectacle lens. A lightweight spectacle lens can be obtained without increasing the peripheral thickness of the concave lens and the center thickness of the convex lens. By using a microprism array as a lens for eyeglasses, it has been necessary to increase the refractive index of the material in order to produce a thin lens. By adjusting the refractive power at the molding stage, it is possible to produce a lens with thin unevenness for spectacles.

  In addition, since the refractive power can be formed without polishing the outer surface and the inner surface, it becomes possible to arbitrarily arrange microlenses having different refractive power depending on the part, and the distortion caused by the difference between the inner and outer surface curves as in the prior art can be reduced. A multifocal lens for eyeglasses without glasses can also be manufactured. In addition, when the conventional polishing method uses a microprism, it is possible to arbitrarily set a power difference that cannot be put to practical use because the strain becomes too large in the conventional polishing method. Since the spectacle lens formed of microprisms as described above is formed of a prism, reflection and stray light are generated at the boundary surface between the prism cells, and this is controlled by controlling the spectral transmittance by coating. This solves this problem.

  FIG. 1 shows an enlarged schematic diagram of the microprism array. At the same time, it solves a new problem that has not occurred in conventional lenses, which is generated by forming a microprism array. Furthermore, it produces a local change in refractive power rather than concentric circles, which could not be formed with conventional Fresnel lenses.

  The diameter of the cone in the retina of the human eye is estimated to be about 4.5 μm to about 5.4 μm. When light emitted from two points forms an image on the retina, it is 2 It cannot be identified as a point. Further, the standard value of visual acuity 1.0 is defined as visual acuity 1.0 if a ring break having a diameter of 7.5 mm and a gap of one fifth of the diameter, ie, 1.5 mm, can be identified from a position 5 meters away. At this time, for a distance of 5 m, the angle formed by the width of 1.5 mm, that is, the viewing angle is exactly 1 minute, that is, 1/60 degrees. Therefore, in order to discriminate between the two points with the standard vision eye The angle between the two points and the eye, that is, the viewing angle needs to be 1 minute or longer, and the distance between the two points at which the viewing angle is 1 minute is about 0.09 mm, that is, about 90 μm.

  In addition, the human eye's ability to adjust changes with age, but in the teens the near point position is approximately 10 cm in front of the eye, and the distance between the two points where the viewing angle near this point is 1 minute is about 0.03. mm, or approximately 30 μm. When this is converted into the resolution of the printed matter, it is about 870 DPI, and even if the eyes are looked at at a near point, the difference between two fine points with a resolution higher than that cannot be identified with the naked eye.

  In the spectacles, the distance between the eye and the spectacle lens when worn, that is, the apex distance is approximately 12 mm. At this distance of 12 mm in front of the eye, the distance between the two points at which the viewing angle is 1 minute is about 0.0035 mm, ie, about 3.5 μm, which is smaller than the diameter of the cone. However, the spectacle lens when worn is inside the near point of the human eye and does not distinguish between the two points on the lens surface, and the purpose is to transmit only light from one point with one prism cell. In practice, it is not necessary to form a fine prism cell so far.

  The resolution of the lens is the fineness corresponding to the ability to disassemble a general "MTF" (Modulation Transfer Function) test, 50 lines / mm, that is, 50 lines of 10 μm drawn at equal intervals between 1 mm. If so, it is considered that there is no problem in practical use, and the size of one side of each prism cell of the microprism array necessary for the spectacle lens is in the range of about 5 μm to 30 μm. In some cases, even if one side of one prism cell is 90 μm or more, it is in a usable range as a spectacle lens. In the current nanotechnology microfabrication technology, microlenses with diameters in the range of several μm to several hundred μm can be manufactured due to advances in processing technology, and this is close to the resolution of the human eye. High-density and fine microlenses or microprisms can be formed.

  However, in the current production technology, a higher technology is required in order to precisely control the individual refractive powers of microprisms made into microcells. The solution to this problem is solved by combining with the prior art, that is, by polishing a lens surface different from the surface on which the microlenses are arranged, that is, by polishing one surface of the inner surface or the outer surface and making a curve difference.

  As described above, when a high-density microprism array is manufactured with a resolution close to that of human photoreceptor cells and used as a spectacle lens, a spectacle lens with little deterioration in resolution or the like can be obtained. Furthermore, since the refractive power of each prism cell on the microprism array can be arbitrarily set depending on the part, not only a single-focus spectacle lens but also a multifocal lens having a plurality of focal lengths can be used as a single spectacle lens. Can be molded. In addition, since the multifocal lens using the microprism array is formed in a form in which an infinite number of fine prisms are arranged, it is difficult for a person other than the wearer to see the change in the power from the outside, so-called many borderless lenses. It becomes a focus lens.

  In conventional progressive multifocal spectacle lenses, power is generated according to the target distance such as for long distance, medium distance, and short distance, so complicated polishing is performed on the front and back surfaces, but it is still partially strong When trying to form the addition power, the distortion also became large. However, when a spectacle lens is formed with a microprism array, it is only necessary to partially form a prism with a strong refractive power, and a single lens with a large power difference that could not be considered with a conventional progressive multifocal lens. Can be formed inside.

  When a spectacle lens is formed by a microprism array, a boundary line is formed between each prism cell, and a subtle difference in height is produced between adjacent prisms. FIG. 2 schematically shows a boundary surface between the prism cells in the cross section of the microprism array. Reflection occurs at this boundary surface, and stray light is generated at the same time. As a result, an image seen through the lens becomes unclear. Therefore, in the formation of the microprism array, it is necessary to design the array so as to minimize the optical influence generated at the boundary surface, and at the same time, to apply a coating process so that the wearer does not feel this reflection or stray light strongly. It becomes.

  In the coating of the microprism array, it is not possible to place a coating layer having such a thickness as to fill the continuous prism cells. The level difference between the prism cells depends on the size of each cell, but is approximately 1 μm or less. Therefore, even if the number of layers is increased, the thickness of the coat layer must be up to about 300 nm. Therefore, a coating design is performed so as to suppress reflected light and stray light by a multilayer coating of about 3 to 4 layers.

  Light that is easy for a wearer to feel stimulation as reflected light or stray light is light in the short-wavelength side and in the band with high visual acuity among visible light, and the coat design transmits light in these two bands with a coat. Lower. Specifically, the coating is performed so as to reduce the transmittance of visible light having a wavelength of about 400 to 430 nm and visible light in a band of about 555 nm to 600 nm. FIG. 3 shows an example of a spectral transmittance curve graph by controlling the spectral transmittance by the coating.

  When a spectacle lens is formed as a microprism array, there are two types of areas and positions occupied by the prism array in the lens, one is a method of arranging the microprism array over the entire lens surface, and one is a partial arrangement It is a method to do. For example, in a bifocal lens for eyeglasses, if a correction power is not required in the distance, the microprism array is formed only in the lower half of the lens, that is, in the near area, and the power for correcting both the distance and the distance Is required, microprisms are arranged and formed on the entire lens surface.

  By making the spectacle lens into a microprism array, it is possible to set an arbitrary refractive power at an arbitrary position without distortion, so that the conventional polishing method is too distorted to withstand use. Even if it is a refractive power difference according to a site | part, it can form, without impairing wearing feeling. FIG. 4 shows an example in which a multifocal lens is formed with an extreme power difference.

  Furthermore, there are two types of means for forming a microprism array in a spectacle lens, one is a method of arranging rectangular prism cells in a grid pattern without gaps, and the other is an arbitrary center point of the spectacle lens. Alternatively, there is a method in which a fan-shaped region surrounded by an infinite number of radiation drawn from a geometric center point and an infinite number of concentric circles is used as one cell of a microprism. By forming prism cells in a rectangular or fan shape in this way, it is possible to change the refractive power even for prism cells that are on the same concentric circle, and the prisms on the same concentric circle as in conventional Fresnel lenses. Do not have the same refractive power, it is possible to change the refractive power depending on the part even on the same concentric circle.

The schematic diagram which expanded the microprism array is shown. The boundary surface between each prism cell in the cross section of a microprism array is shown typically. The example of the spectral transmittance curve graph by control of the spectral transmittance by a coat is shown. An example in which a multifocal lens is formed with an extreme frequency difference is shown.

Claims (2)

  A spectacle lens characterized in that microprisms are arranged in an integrated manner on the inner surface or outer surface with a resolution equivalent to or higher than the resolution of human eyes, and the refractive power of the microlens is changed depending on the part.   2. The spectacle lens according to claim 1, wherein a multilayer film coating is applied to reduce visible light transmittance in a wavelength range of about 400 to 430 nm and about 555 to 600 nm.