JP5115364B2 - Method for calculating inclination angle of spectacle lens, spectacles, and method for manufacturing spectacles - Google Patents

Description

  The present invention relates to a method for designing a spectacle lens attached to a spectacle frame having a large warp angle, such as a wrap-around spectacle frame, and spectacles.

In recent years, wraparound type spectacle frames have been used mainly as sunglasses for sports. This wrap-around type spectacle frame has a feature that it has a large warp angle and bends along the face, so there is a lens on the side of the face and a wide field of view. Therefore, it is used habitually by athletes as protective eyeglasses for sports and eyeglasses for eye protection.
The wrap-around type spectacle lens has an optical convex surface on the object side and a near optical concave surface on the eyeball side, and is attached to the spectacle frame tilted with respect to the front line of sight (Patent Document 1). .

The optical concave surface of the spectacle lens is prescribed for myopia or hyperopia depending on the degree of visual acuity of the user. Therefore, a plurality of types of spectacle lenses are designed, but many spectacle frames attached to the spectacle lenses are commonly used.
Conventionally, a spectacle lens is attached to a spectacle frame by applying an optical convex surface located on the object side so as to follow the outer shape of the spectacle frame.

JP 2005-284059 A

In a spectacle lens, light incident from the object side is refracted by an optical convex surface, travels straight through the lens, is refracted again by the optical concave surface, and enters the pupil of the user.
Here, since the optical concave surface on the eyeball side is prescribed according to the visual acuity of the user or the like, the surface is different for each eyeball lens.
Since the conventional spectacle lens is only attached based on the outer shape of the spectacle frame, there is a problem that the optical concave surface on the eyeball side does not have an appropriate angle with respect to the spectacle frame depending on the prescription applied to the optical concave portion. .
When the optical concave surface is tilted from an appropriate angle, average power error, astigmatism, and prism error occur. Such an error may cause eyestrain and the like for the user.

  An object of the present invention is to provide a method and a spectacle for designing a spectacle lens in which various errors are unlikely to occur regardless of the prescription applied to the optical concave portion on the eyeball side.

The present invention has been made paying attention to the fact that various errors such as an average power error occur when a spectacle lens is attached to a spectacle frame in a state where the optical concave surface is inclined with respect to an appropriate angle.
Specifically, the spectacle lens design method of the present invention includes a spherical optical convex surface disposed on the object side and an optical curved optical concave surface corresponding to the prescription disposed on the eyeball side, so that the A method of designing a spectacle lens tilted and attached to a spectacle frame, wherein a point corresponding to the front line of sight of the optical concave surface is defined as a design reference point, and a tangent at the design reference point and a plane orthogonal to the front line of sight are formed. The lens tilt angle θ defined by the angle is used.

In the invention of this configuration, the lens tilt angle θ is obtained for each spectacle lens, and the spectacle lens is attached to the spectacle frame according to the lens tilt angle θ.
For this reason, since the inclination of the optical concave surface can be made appropriate by setting the lens inclination angle θ, the spectacle lens is attached to the spectacle frame so that the optical concave surface is at an appropriate angle regardless of prescription such as myopia and hyperopia. Can be attached. Accordingly, the average power error, astigmatism, and prism error are reduced, and eyeglasses are not tired from the eyeglass user.

In the present invention, the optical concave surface is preferably an aspherical surface.
In the invention of this configuration, the average power error, astigmatism, and prism error can be further reduced.

In the present invention, the lens tilt angle θ is defined by the distance between the pupil, the lens width of the spectacle lens, and a straight line connecting the peripheral edges formed on the opposite sides of the optical convex surface side defining the lens width and the front line of sight A front warp angle formed by an angle formed with an orthogonal plane orthogonal to each other, a bridge length defined by a dimension between adjacent spectacle lenses, a front curvature formed by a radius of curvature of the optical convex surface, and the center of the spectacle lens A configuration obtained from the thickness is preferable.
In the invention of this configuration, the parameter for defining the lens tilt angle θ is set regardless of the optical concave surface whose shape varies depending on the prescription, so that the lens tilt angle θ can be easily obtained.

  Further, an expression of the spherical surface of the optical convex surface of the spectacle lens is obtained from the ball width of the spectacle lens, the front warp angle, the bridge length, and the curvature of the front surface, and intersects with a straight line parallel to the front line of sight of the spherical surface. The tangent equation at the point to be calculated is determined, the conditions for the multiple rays incident on the pupil are set in the tangent equation, and the light rays emitted under these conditions are calculated by calculating the rays passing through the pupil, and the appropriate incident rays are selected. A configuration in which the angle between the tangent to the selected incident ray and the orthogonal plane is the lens tilt angle θ is preferable.

In the invention of this configuration, a tangent equation that touches the spherical surface of the straight line is obtained from the equation of the spherical surface of the optical convex surface located on the object side and a straight line parallel to the frontal line of sight. As well as setting, a light beam emitted under these conditions is calculated as a light beam passing through the pupil.
In this calculation, the object-side optical convex surface and the eyeball-side optical concave surface of the spectacle lens are approximated by a plate-like prism having two parallel surfaces parallel to each other. The light beam incident on the object side surface of the prism of the plate material is once refracted and travels straight inside the plate material, and then refracts again from the side surface of the eyeball and exits to the eyeball side. Since the angle formed by the plane perpendicular to the angle differs depending on the position of the incident light beam, the position to be emitted for each of the plurality of incident light beams is obtained by simulation, and the incident light beam whose emission position coincides with the front line of sight is, for example, Obtained by the convergence calculation method.
An angle formed between the incident plane of the incident light beam in which the front line of sight coincides with the outgoing light beam and the orthogonal plane is defined as a lens tilt angle θ.
Therefore, in the present invention, since the inclination of the optical concave surface can be obtained by calculation using the above-mentioned parameters regardless of the prescription, a more accurate lens inclination angle θ can be set.

The spectacles of the present invention are those in which a spectacle lens designed by the spectacle lens design method having the above-described configuration is attached to the spectacle frame.
In the invention with this configuration, it is possible to provide glasses capable of producing the above-described effects.

Hereinafter, a method for designing a spectacle lens according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic horizontal sectional view of the glasses of this embodiment.
In FIG. 1, the spectacles are attached to the spectacle frame 2 with two spectacle lenses 1 inclined with respect to the front line of sight P.
The spectacle lens 1 is a meniscus lens having an optical convex surface 11 disposed on the object side and an optical concave surface 12 disposed on the eyeball side. The radius of curvature of the optical convex surface 11, that is, the front curvature r is formed in a spherical shape having a predetermined dimension.

The eyeglass frame 2 is a wraparound type eyeglass frame having a large warp angle of 200 ° or more. The spectacle frame 2 has a front surface curved in a substantially spherical shape, and a bridge 21 for applying a nose, a temple 22 for applying an ear, and an edge 23 for attaching the spectacle lens 1 are integrally formed. Has been.
The optical convex surface 11 of the spectacle lens 1 is formed into a spherical surface, and the spectacle lens 1 is attached to the spectacle frame 2 so that the spherical surface corresponds to a curved portion formed on the spherical surface of the front portion of the spectacle frame 2.
The optical concave surface 12 has an aspherical shape because necessary processing such as myopia and hyperopia is performed.

Two frontal lines of sight P that are parallel to each other are defined for the glasses, and the distance between these frontal lines of sight P is the inter-pupil distance PD. This interpupillary distance PD has a different value depending on the user.
The bridge 21 of the spectacle frame 2 has a nose width dimension defined as a bridge length L. The bridge length L is a linear dimension on the front side of the bridge 21 in a plane including the front line of sight P. The bridge length L is also the dimension between the edges of the optical convex surface 11 of the adjacent spectacle lens 1.

FIG. 2 shows an enlarged schematic view of the spectacle lens 1.
In FIG. 2, the spectacle lens 1 has a ball width of W and a front warp angle of α. The ball width W is a dimension between the edges 11A and 11B that are separated from each other in the plane including the front line of sight P of the optical convex surface 11, and the front warp angle α is the optical in the plane including the two front lines of sight P. It is defined by an angle between a straight line S connecting the edges 11A and 11B of the convex surface 11 and a plane Q perpendicular to the front line of sight P.
A point corresponding to the front line of sight P of the optical concave surface 12 is set as a design reference point Pi, and a plane Q orthogonal to the tangent line C and the front line of sight P in the horizontal plane at the design reference point Pi, that is, in a plane including the two front lines of sight P. Is the lens tilt angle θ.
The thickness dimension at the design reference point Pi of the spectacle lens 1 is the center thickness t.

Next, a method for designing a spectacle lens according to the present embodiment will be described with reference to FIG.
FIG. 3 is a schematic diagram for explaining a design method of the spectacle lens 1.
First, the formula of the spherical surface of the optical convex surface 11 of the spectacle lens is obtained from the ball width W, front warp angle α, bridge length L, and front curvature r of the spectacle lens 1.
The expression of the spherical surface of the optical convex surface 11 is (X−Xo) ² + (Y−Yo) ² + (Z−Zo) ² = r ² .
Here, when Xo, Yo, and Zo are coordinates of the center position of the spherical surface, the center position is obtained from the ball width W, the front warp angle α, and the bridge length L of the spectacle lens 1.

Then, an equation of a tangent Cn at a point intersecting the light ray Pn parallel to the spherical front view line P is obtained.
The condition of a plurality of light rays Pn (n = 1, 2, 3,...) Incident on the pupil is set in the expression of the tangent Cn, and the light rays Pn emitted under these conditions are calculated by the convergence calculation method. Thus, an appropriate incident light beam is selected (see FIG. 3).
In this calculation, the object-side optical convex surface 11 and the eyeball-side optical concave surface 12 of the spectacle lens 1 are approximated to two tangents Cn parallel to each other. The spectacle lens 1 has the same distance as the center thickness t of the spectacle lens 1 between the two tangents Cn. In other words, the spectacle lens 1 having the optical concave surface 12 and the spherical optical convex surface 11 having different inclination angles is treated as a plate-like prism having an entrance surface and an exit surface parallel to each other.

The light ray Pn incident on the object side surface is refracted once and travels straight inside, and then refracted again from the eyeball side surface and emitted toward the eyeball side to become a light ray Pn ′.
The angle θn formed between the tangent line Cn that is the incident surface and the plane Qn that is orthogonal to the front line of sight P differs depending on the position of the incident light ray Pn in the horizontal plane.
For example, as shown in FIG. 3, when light rays Pn incident is a ray P ₁ to the rightmost, the light P ₁ is refracted at the tangent C ₁ on the incident side, again refracted at the tangent C ₁ on the exit side And becomes output light P ₁ ′. In this case, the angle formed by the plane Q ₁ and the tangent line C ₁ is θ ₁ .
In contrast, when light rays Pn incident is a ray P ₂ of the leftmost, this ray P ₂ refracts at the tangent C ₂ on the incident side, light emitted is refracted again at the tangent line C ₂ on the exit side P ₂ ′. In this case, the angle formed between the plane Q ₂ and the tangent line C ₂ is θ ₂ . The angle θ ₂ is larger than θ ₁ .
Therefore, the light ray Pn ′ emitted for each of the plurality of incident light rays Pn is simulated.

Of the incident light Pn, an incident light Pn in which the position of the light Pn ′ emitted through the spectacle lens 1 coincides with the front line of sight P is obtained by, for example, a convergence calculation method.
First, the first light ray P ₁ is emitted, and the distance (dimension in the Y-axis direction in FIG. 3) between the outgoing light P ₁ ′ of this light ray P ₁ and the front line of sight P is obtained. If this distance is positive, for example, the second light ray P ₂ is emitted from the negative direction, and the distance between the outgoing light P ₂ ′ of the light ray P ₂ and the front line of sight P is obtained. Once this distance is, for example, negative, it emits third light P ₃ at a position between the light rays P ₁ and P _2. Repeat this simulation is performed until the output light beam Pn 'coincides with the forward sight line P, matched incident light Pn, e.g., the angle theta ₃ between the tangent line C ₃ is a plane of incidence of the incident light beam P ₃ orthogonal planes Q ₃ Is the lens tilt angle θ.
In this embodiment, prism correction is performed as necessary.

Next, a method for manufacturing the spectacle lens 1 designed by the design method of the present embodiment will be described with reference to FIG. In the present embodiment, the spectacle lens 1 is molded by casting a semi-finished lens blank.
4A to 4D are schematic cross-sectional views showing the manufacturing process of the spectacle lens 1.
First, as shown in FIG. 4A, in this embodiment, two molds, that is, a first mold 110 and a second mold 120 are used. The 1st shaping | molding die 110 has the convex surface 111 which shape | molds the concave surface side of a semifinished lens blank, and the lower surface 112 of a non-molding surface. The 2nd shaping | molding die 120 has the concave surface 121 which shape | molds the convex surface side of a semifinished lens blank, and the upper surface 122 of a non-molding surface.

The first mold 110 is a glass mold in which the molding surface of the convex surface 111 and the lower surface 112 are both formed into a spherical surface, the thickness is substantially uniform, and not only the convex surface 111 but also the lower surface 112 is formed on the optical surface. The center of the spherical surface of the convex surface 111 and the center of the spherical surface of the lower surface 112 both exist on the geometric center line, and the molding surface and the lower surface 112 of the convex surface 111 are rotationally symmetric surfaces having the geometric center line as the symmetry axis.
The second mold 120 is a glass mold in which the molding surface of the concave surface 121 and the upper surface 122 are both formed into a spherical surface, and not only the concave surface 121 but also the upper surface 122 is formed on the optical surface. The center of the spherical surface of the upper surface 122 is on the geometric center line, and thus is a rotationally symmetric surface with the geometric center line as the axis of symmetry. The center of the concave surface 121 is an inclined spherical surface that deviates from the geometric center line toward the ear. Therefore, the thickness of the second mold 120 is not uniform and the thickness is uneven. If both surfaces are spherical and the thickness is biased, prism refractive power is generated on the geometric center line of the lens. The fitting point set on the front surface of the lens as a reference point is set at a predetermined position on the side where the thickness of the second mold 120 is increased at a position away from the geometric center of the concave surface 121 of the second mold 120. Has been. Further, although not shown, a hidden mark for notifying the position of the reference fitting point is imprinted on the concave surface 121 of the second mold 120, for example, on both sides of a straight line equidistant from the fitting point, so that the semi-finished lens blank 3 Is transferred to the convex surface 31 (see FIG. 4C).

As shown in FIG. 4B, the first mold 110 and the second mold 120 are separated from each other by a predetermined distance with the convex surface 111 of the first mold 110 and the concave surface 121 of the second mold 120 facing each other. In such a state, the two molds 110 and 120 are arranged so that the side surfaces coincide with each other on the basis of the outline. Then, the adhesive tape 130 is wound so as to straddle these side faces while maintaining the positions of the first mold 110 and the second mold 120, and the gap between the first mold 110 and the second mold 120 is adhered. The cavity 140 is formed by sealing with the tape 130, and the lens casting mold 150 is assembled.
The mold 150 assembled in this way is a spherical surface in which the lower surface 112 and the convex surface 111 of the first mold 110 and the upper surface 122 of the second mold 120 are centered on the geometric center line. Only the spherical surface of the concave surface 121 is an inclined spherical surface whose center does not coincide with the geometric center line.

Next, the lens material is filled in the cavity 140 of the sealed space surrounded by the first mold 110, the second mold 120, and the adhesive tape 130 of the mold 150, and the lens material is polymerized and cured by light energy or heat energy. .
After the polymerization and curing, the adhesive tape 130 is peeled off, and the first mold 110 and the second mold 120 are separated to obtain the semifinished lens blank 3 as shown in FIG. The semi-finished lens blank 3 is an eccentric lens in which the convex surface 31 and the concave surface 32 are spherical surfaces, have a prism refractive power on the geometric center line, and the fitting point is deviated from the geometric center to the nose side. .
As shown in FIG. 4D, the concave surface side (eyeball side) 32 of the obtained semifinished lens blank 3 is cut, ground, and mirror-polished to form the optical concave surface 12.
The spectacle lens 1 manufactured in this way is attached to the spectacle frame 2. At this time, in selecting the spectacle lens 1, the lens tilt angle θ is also used as a reference.

Therefore, in the present embodiment, the following operational effects can be achieved.
(1) A point corresponding to the front line of sight P of the optical concave surface 12 is set as a design reference point Pi, and the spectacle lens 1 is formed using a lens inclination angle θ formed by a tangent C at the design reference point Pi and a plane Q orthogonal to the front line of sight P. Since it is designed, even if the optical concave surface 12 has a complicated aspherical shape due to prescription, the average power error, astigmatism, and prism error do not occur.

(2) The lens tilt angle θ is obtained from the interpupillary distance PD, the lens lens width W, the front warp angle α, the bridge length L, the front curvature r, and the center thickness t of the spectacle lens 1. Therefore, since these parameters are set regardless of the aspherical shape of the optical concave surface 12 whose shape varies depending on the prescription, the lens tilt angle θ can be easily obtained by simulation using a computer or the like.

(3) From the lens width W of the spectacle lens 1, the front warp angle α, the bridge length L, and the curvature r of the front surface, the spherical formula of the optical convex surface of the spectacle lens is obtained, and the light ray Pn parallel to the frontal line of sight P of this spherical surface. The tangent line Cn expression at the point intersecting with the tangent line Cn is obtained, and the condition of the plurality of light rays Pn incident on the pupil I is set in the tangent line Cn expression. Is selected to select an appropriate incident light beam, and the angle between the tangent line and the orthogonal plane in the selected incident light beam is set as a lens tilt angle θ. For this reason, the object-side optical convex surface 11 and the eyeball-side optical concave surface 12 of the spectacle lens 1 are approximated to be two parallel surfaces parallel to each other, so that the calculation is facilitated. Can be obtained by a convergence calculation method or the like, so that a more accurate lens tilt angle θ can be set.

(4) A semi-finished lens blank in which the first molding die 110 having a spherical optical convex surface 111 and the second molding die 120 having a spherical optical concave surface 121 are made to coincide with each other and to be molded is formed. A semi-finished lens having a prism refractive power on the geometric center line by forming the optical convex surface 111 and the optical concave surface 121 to face each other so as to have a prism refractive power on the geometric center line. Blank 3 was produced. Therefore, it is possible to secure a lens shape of the spectacle lens that fits the wraparound type spectacle frame with a semi-finished lens blank having a diameter for a normal spectacle lens.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above embodiment, the lens tilt angle θ is obtained by a convergence calculation method or the like. However, in the present invention, the method for obtaining the lens tilt angle θ is not limited to the convergence calculation method, and is frequently used in mathematics, for example. Various calculation methods can be used.
In the present invention, the spectacle lens 1 may be manufactured by polishing both surfaces of the lens blank.
Furthermore, in the present invention, the optical concave surface 12 may be a spherical surface.

  INDUSTRIAL APPLICABILITY The present invention can be used for a spectacle lens to be incorporated into a wraparound type spectacle frame.

1 is a schematic horizontal sectional view of eyeglasses according to an embodiment of the present invention. The enlarged schematic diagram of the spectacle lens integrated in the spectacles frame. Schematic for demonstrating the design method of a spectacle lens. (A)-(d) is a schematic sectional drawing which shows the manufacturing process of an eyeglass lens.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Eyeglass lens, 11 ... Optical convex surface, 12 ... Optical concave surface, 2 ... Eyeglass frame, 21 ... Bridge, (theta) ... Lens tilt angle, PD ... Interpupillary distance, W ... Ball width, alpha ... Front curvature angle, L ... Bridge Length, r ... Front curvature, t ... Eyeglass lens center thickness

Claims (5)

A spherical optical convex surface arranged on the object side and an optical concave optical surface corresponding to the prescription arranged on the eyeball side are formed, and the inclination angle of the spectacle lens attached to the spectacle frame is tilted with respect to the front line of sight. A way to
The point corresponding to the front line of sight of the optical concave surface is a design reference point,
It consists of an angle between a pupillary distance, a lens width of the spectacle lens, a straight line connecting peripheral edges formed on opposite sides of the optical convex surface side defining the lens width, and an orthogonal plane orthogonal to the front line of sight Finding the front curvature angle, the bridge length defined from the dimension between the adjacent spectacle lenses, the front curvature consisting of the radius of curvature of the optical convex surface, and the center thickness of the spectacle lens,
Obtain the spherical formula from the lens width of the spectacle lens, the front warp angle, the bridge length, the curvature of the front surface,
The optical convex surface and the optical concave surface are approximated to a plate-like prism having object side surfaces and eyeball side surfaces that are parallel to each other, and a plurality of incident light rays are incident on the object side surface of the prism and refracted once inside the prism. Then, after going straight ahead, the optical path that is refracted and emitted again from the side of the eyeball is obtained by simulation ,
Obtaining one of the plurality of incident light rays in which the optical path after exiting from the side surface of the eye coincides with the front line of sight;
The exit position of one of the plurality of incident rays whose optical path after exiting from the side surface of the eye coincides with the front line of sight is set as the design reference point,
A method for calculating an inclination angle of a spectacle lens, wherein an angle formed between a tangent line at the design reference point and a plane orthogonal to the front view line is defined as the lens inclination angle. In the method for calculating the inclination angle of the spectacle lens according to claim 1,
A method for calculating an inclination angle of a spectacle lens , wherein the optical concave surface is an aspherical surface. The spectacles which attached the spectacles lens by which the inclination | tilt angle was calculated by the method of Claim 1 or Claim 2 to the said spectacles frame. A method for manufacturing spectacles in which a spherical optical convex surface arranged on the object side and an optical concave optical surface corresponding to a prescription arranged on the eyeball side are formed, and the spectacle lens is attached to the spectacle frame inclined with respect to the front line of sight. There,
The point corresponding to the front line of sight of the optical concave surface is a design reference point,
It consists of an angle between a pupillary distance, a lens width of the spectacle lens, a straight line connecting peripheral edges formed on opposite sides of the optical convex surface side defining the lens width, and an orthogonal plane orthogonal to the front line of sight Finding the front curvature angle, the bridge length defined from the dimension between the adjacent spectacle lenses, the front curvature consisting of the radius of curvature of the optical convex surface, and the center thickness of the spectacle lens,
Obtain the spherical formula from the lens width of the spectacle lens, the front warp angle, the bridge length, the curvature of the front surface,
The optical convex surface and the optical concave surface are approximated to a plate-like prism having object side surfaces and eyeball side surfaces that are parallel to each other, and a plurality of incident light rays are incident on the object side surface of the prism and refracted once inside the prism. Then, after going straight ahead, the optical path that is refracted and emitted again from the side of the eyeball is obtained by simulation,
Obtaining one of the plurality of incident light rays in which the optical path after exiting from the side surface of the eye coincides with the front line of sight;
The exit position of one of the plurality of incident rays whose optical path after exiting from the side surface of the eye coincides with the front line of sight is set as the design reference point,
An angle formed between a tangent line at the design reference point and a plane perpendicular to the front view line is the lens tilt angle,
A method for manufacturing spectacles, wherein a spectacle lens is attached to a spectacle frame in accordance with the lens tilt angle. In the manufacturing method of the spectacles described in Claim 4,
The method for manufacturing eyeglasses, wherein the optical concave surface is an aspherical surface.

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