JP4780937B2 - Mold design method, mold and mold manufacturing method - Google Patents

Description

  Even when the optical lens is deformed when the optical lens is molded from the mold, the present invention provides a method for designing the mold that molds the optical lens in consideration of the deformation. The present invention relates to a mold designed by a design method and an optical lens molded by the mold.

  When molding an optical lens with a molding die, due to shrinkage depending on the material in each part of the optical lens, stress due to the shape of the optical lens, etc., the molding surface of the molding die is as designed by the design surface of the optical lens In general, the optical lens after molding does not have the same shape as the design curved surface of the optical lens. For example, when a spherical lens is molded using a molding die with a molding surface formed into a spherical shape so as to mold a spherical lens, the optical lens as a molded product has a shape other than a spherical surface including an aspherical shape. . Therefore, in order to manufacture an optical lens having a curved surface having the same shape as the design curved surface of the optical lens, it is necessary to appropriately correct the molding surface of the mold.

  The shape error due to the molding of this optical lens and the correction amount of the molding surface of the molding die derived from the error differ depending on the refractive power of the optical lens, the lens material, and the shape of the design curved surface. Have. In order to determine an appropriate correction amount, it is necessary to experimentally verify the actual deformation in each mold.

  The determination of the correction amount is mainly based on the experience of the operator, and skill is required. Moreover, in order to obtain an accurate correction amount even for a skilled person, it takes time to perform many molding tests for each new product, and repeats trials to converge the correction amount to a predetermined range. ing.

  Specifically, (a) all types of optical lenses are test-molded with corresponding molds, and (b) errors with respect to the design values of the optical lenses are measured. Then, (c) a temporary correction amount (experience value) is calculated by multiplying the measured error by various coefficients to recreate the mold. (D) The optical lens is test-molded again using the remade mold, and (e) the shape error of the optical lens is measured. The above corrections (c) to (e) are repeated to optimize the correction.

  However, many molding tests are required to converge the correction amount. Further, in the case of an optical lens, for example, a spectacle lens, the number of types is 300 or more for each new product, the number of molds is about 600, and all types are 10,000 or more. Work for several months each time a new product is released.

  Conventionally, with respect to the correction amount to be applied to the molding surface of the molding die, a spherical shape having a single curvature is obtained using the least square method so that the error between the molded optical lens and the design value of the optical lens is minimized. There is a method of correcting the mold using the curvature of the spherical shape as an average curvature (first conventional technique).

  Further, as a second conventional technique, in the case of a simple shape, a deformation considering shrinkage can be predicted, and there is a method of applying this predicted value as a correction amount (Patent Document 1).

Furthermore, as a third conventional technique, there is a method of measuring a shape error with a design value and using the measured shape error value itself as a correction amount (Patent Document 2).
JP 2003-117925 A JP-A-8-216272

  However, in the error evaluation based on the average curvature in the first conventional technique, it is not possible to evaluate a shape error other than the spherical shape, and therefore it is not possible to correct a shape error other than the spherical shape.

  Further, even if an optical lens mold is designed using the second conventional technique, when the optical lens is a spectacle lens, for example, it has a meniscus shape consisting of a convex surface and a concave surface, and the shape is complicated. Since high accuracy is required, it is difficult to design a mold by predicting deformation considering shrinkage.

  Further, in the third conventional technique, in order to obtain the correction amount, it is necessary to measure a shape error with respect to a set value with respect to a test-molded molded product, and the molded product can be molded efficiently. Can not.

The object of the present invention has been made in consideration of the above-described circumstances, and even when the optical lens is deformed when the optical lens is molded from the mold, a desired transmission refractive power is obtained at the apex. It is an object of the present invention to provide a mold designing method capable of molding an optical lens having the following.
Another object of the present invention is to provide a mold capable of forming an optical lens having a desired transmission refractive power at the apex even when the optical lens is deformed when the optical lens is molded from the mold. There is to do.
Still another object of the present invention is to provide an optical lens that can have a desired transmission refractive power at the apex even when the optical lens is deformed when it is molded from a mold. .

  The molding die design method according to the invention of claim 1 is a molding die design method for molding an optical lens, based on the shapes of both design curved surfaces on the first surface and the second surface of the optical lens, An error due to the shaping of the transmission refractive power at the apex of the optical lens to be molded is predicted, and the mold is corrected and designed using correction information corresponding to this error.

According to a second aspect of the present invention, there is provided the mold designing method according to the first aspect, wherein the design surfaces of the first surface and the second surface of the optical lens are designed to be the first surface. When the curvature radius of the curved surface is Ra and the curvature radius of the design curved surface of the second surface is Rb, it is defined by the shape factor SP calculated by the following equation (1).
SP = (Rb + Ra) / (Rb−Ra) (1)

According to a third aspect of the present invention, there is provided the molding die design method according to the second aspect of the invention, wherein the error α due to the shaping of the transmission refractive power at the apex of the molded optical lens is the first surface of the optical lens. , When the curvature radius of the design curved surface on each of the second surfaces is Ra, Rb, the shape factor of the optical lens is SP, the refractive index of the optical lens is n, and the coefficient depending on the material of the optical lens is A And is calculated by the following equation (2).

  According to a fourth aspect of the present invention, there is provided the mold designing method according to any one of the first to third aspects, wherein the correction of the mold is performed on each of the first surface and the second surface of the optical lens. The entire molding surface of at least one of the first molding surface and the second molding surface to be molded is corrected.

  According to a fifth aspect of the present invention, there is provided a molding die formed by performing the molding die design method according to any one of the first to fourth aspects.

  An optical lens according to a sixth aspect of the invention is characterized by being molded using the molding die according to the fifth aspect.

  An optical lens according to a seventh aspect of the invention is the optical lens according to the sixth aspect of the invention, wherein the optical lens is a meniscus spectacle lens.

  According to the first to fourth aspects of the present invention, based on the shapes of the design curved surfaces of the first surface and the second surface of the optical lens, an error due to the molding of the transmission refractive power at the apex of the molded optical lens is predicted. Since the mold is corrected and designed using the correction information corresponding to this error, even when the optical lens is deformed when the optical lens is molded from the mold, a desired shape is obtained at the apex. An optical lens having transmission refractive power can be molded.

  In addition, based on the shape of both design curved surfaces on the first and second surfaces of the optical lens, the error due to the transmission refractive power molding at the apex of the molded optical lens is predicted, so the optical lens is test-molded with a molding die. In addition, since it is not necessary to measure the shape of the molding curved surface of the optical lens formed by the test, an optical lens having a desired transmission refractive power at the apex can be efficiently molded.

  In addition, the first lens surface of the optical lens is predicted from the error due to the molding of the transmission refractive power at the apex of the molded optical lens by simultaneously considering the shapes of the design curved surfaces on the first surface and the second surface of the optical lens. Even when the curvatures of the design curved surfaces of the surface and the second surface are significantly different, the molding die can be corrected with high accuracy based on the molding error.

  According to the invention described in claims 5 to 7, even when the optical lens is deformed when the optical lens is molded from the molding die, both the first surface and the second surface of the optical lens are deformed. Based on the shape of the design curved surface, the error due to the molding of the refractive power at the apex of the optical lens to be molded is predicted, and the design is made by correcting the mold so that the optical power at the apex has the desired value. It can be obtained by molding a lens.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view showing a molding die having an upper mold and a lower mold manufactured by carrying out an embodiment of the molding die design method according to the present invention. FIG. 2 is a side sectional view showing an optical lens molded by the mold shown in FIG.

  A molding die 10 shown in FIG. 1 is for molding a plastic optical lens (for example, a meniscus spectacle lens) by a manufacturing method called a casting method, and has an upper mold 11, a lower mold 12, and a gasket 13. Configured. The upper mold 11 and the lower mold 12 are collectively referred to as a lens matrix.

  The gasket 13 is formed in a cylindrical shape with an elastic resin, and holds the upper mold 11 and the lower mold 12 on the inner peripheral surface in a liquid-tight manner with a predetermined distance therebetween. A cavity 14 is formed by being surrounded by the upper mold 11, the lower mold 12 and the gasket 13. The gasket 13 is integrally provided with an injection portion 15 for injecting a monomer as a raw material of the optical lens 20 (FIG. 2) into the cavity 14. The height of the gasket 13 is set to a dimension that can secure the thickness of the peripheral edge of the optical lens 20 that is a molded product.

  The upper mold 11 and the lower mold 12 are made of glass or the like. The upper mold 11 is formed in a concave mold so as to form the first surface (convex surface) 21 of the optical lens 20 shown in FIG. The lower mold 12 is formed in a convex shape so as to form the second surface (concave surface) 22 of the optical lens 20. In these upper mold 11 and lower mold 12, the surfaces forming the lens curved surfaces (first surface 21, second surface 22) of the optical lens 20 are used surfaces (in the case of the upper mold 11, the first use). In the case of the surface 16A and the lower mold 12, it is referred to as a second use surface 16B), and the surface that does not form the lens curved surface is referred to as a non-use surface 17.

A manufacturing procedure of the optical lens 20 using the mold 10 will be described with reference to FIG.
First, a monomer that is a raw material of the optical lens 20 is prepared (S1). This monomer is a thermosetting resin, which is prepared by adding a catalyst and an ultraviolet absorber to the resin, and is filtered through a filter (S2).

  Next, the upper mold 11 and the lower mold 12 are assembled to the gasket 13 to complete the mold 10 (S3). Then, the monomer prepared as described above is injected into the cavity 14 of the mold 10 and is cured by heat polymerization in an electric furnace (S4). When the polymerization of the monomer is completed in the mold 10, the plastic optical lens 20 is molded, and the optical lens 20 is released from the mold 10 (S5).

  After the optical lens 20 is released, a heat treatment called annealing is performed in order to remove distortion inside the lens caused by polymerization (S6). Thereafter, an appearance inspection and a projection inspection are performed on the optical lens 20 as an intermediate inspection.

  The optical lens 20 is divided into a finished product and a semi-finished product (semi-finished product) at this stage, and the second surface 22 is polished according to the prescription for the semi-finished product. The finished product is then subjected to a dyeing process for obtaining a color product, a reinforcing coating process for strengthening scratches, and an antireflection coating process for antireflection (S7), and a final inspection is carried out (S8). . The finished product becomes a product after this final inspection (S9).

  A manufacturing procedure of the upper mold 11 and the lower mold 12 of the mold 10 used in the manufacturing process of the optical lens 20 will be described below with reference to FIG.

  Since the upper mold 11 and the lower mold 12 can be obtained by processing both sides of a thick glass blank that has been pressed, first, this glass blank is prepared (S11). By processing this glass blank, the surface defect layer on the press surface of the glass blank is removed, and the use surface 16 and the non-use surface 17 are made to have a predetermined precision radius of curvature, and at the same time, the fine and uniform roughness is used with high accuracy. A surface 16 and a non-use surface 17 are obtained. The above processing of glass blanks is performed by grinding and polishing.

  Specifically, in the grinding process, a diamond wheel is used in a free-form surface grinding machine that performs NC control, and both surfaces (the use surface 16 and the non-use surface 17) of the glass blank are ground to a predetermined radius of curvature (S12). By this grinding, the upper mold 11 and the lower mold 12 are formed from the glass blanks.

  In the polishing process, an upper mold 11 and a lower mold formed by grinding using a polishing dish in which polyurethane or felt is bonded to a rubber hollow dish and using fine particles such as cerium oxide and zirconium oxide as an abrasive. 12 is polished (S13). By this polishing process, surface irregularities on the use surface 16 and the non-use surface 17 of the upper mold 11 and the lower mold 12 generated in the grinding process are removed to make the surface transparent (with no graining). The surface 16 and the non-use surface 17 are effectively finished with sufficient surface accuracy.

  After this polishing step, the upper mold 11 and the lower mold 12 are inspected (S14), and a hidden mark serving as a reference position of the layout pattern is marked on the use surface 16 (S15). The layout pattern indicates an optical layout of the optical lens 20 and is used when the circular optical lens 20 is framed in a spectacle frame, and is marked on the surface of the optical lens 20 so as to be erasable. The

  After marking the hidden mark, a scientific glass strengthening process is performed on the upper mold 11 and the lower mold 12 (S16), and the upper mold 11 and the lower mold 12 are completed (S17). Since the upper mold 11 and the lower mold 12 are manufactured according to the refractive power of the prescription of the optical lens 20, many types are necessary together with the gasket 13.

The design procedure of the upper mold 11 and the lower mold 12 in the mold 10 manufactured as described above will be described next.
First, design values of the optical lens 20 to be molded by the mold 10 will be described with reference to FIG. That is, the design curved surface of the first surface 21 of the optical lens 20 is spherical or aspherical, and the radius of curvature at the vertex O1 is set to Ra. The design curved surface of the second surface 22 of the optical lens 20 is also spherical or aspherical, and the radius of curvature at the vertex O2 is set to Rb.

At this time, the shape factor SP that defines the shapes of both design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20 is calculated by the following equation (1).
SP = (Rb + Ra) / (Rb-Ra) (1)
In this formula (1), Rb = Ra is excluded because it is a singular point. In the case where the optical lens 20 is a meniscus spectacle lens having the first surface 21 as a convex surface and the second surface 22 as a concave surface, a shape factor SP is obtained in a negative lens where Rb <Ra and the center thickness of the lens is thin. Become negative. In addition, in a plus lens where Rb> Ra and the center thickness of the lens is thick, the shape factor SP is positive.

  Next, as shown in FIG. 1, the first use surface 16 </ b> A as the first molding surface in the upper mold 11 of the molding die 10 for molding the optical lens 20 is designed on the first surface 21 of the optical lens 20. Molded into a curved surface. At the same time, the second use surface 16B as the second molding surface in the lower mold 12 of the mold 10 is designed to be a design curved surface on the second surface 22 of the optical lens 20.

Assuming that the optical lens 20 is molded using the molding die 10 having the upper mold 11 and the lower mold 12 designed as described above, the transmission refractive power (hereinafter, referred to as the vertex O) of the molded optical lens 20 is described below. "Vertex transmission refractive power P (unit D (diopter))") is caused by molding with respect to the vertex transmission refractive power P in the design value of the optical lens 20 due to the shape of the optical lens 20. Is produced. Therefore, the molding error α (unit D (diopter)) in the vertex transmission refractive power P of the optical lens 20 is predicted by the following equation (2).

In this equation (2), the curvature radii Ra and Rb are the curvature radii (unit: mm) of the design curved surface in each of the first surface 21 and the second surface 22 of the optical lens 20 as described above, and SP is This is a shape factor that defines the shapes of both design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20. N is the refractive index of the optical lens 20, and A is a coefficient determined by the material of the optical lens 20. When n = 1.699, A = 3. The above equation (2) when A = 3 becomes the following equation (3).

但し、Ｄ１＝（ｎ−１）×１０００／Ｒａ、
Ｄ２＝（ｎ−１）×１０００／Ｒｂである。 FIG. 5 shows the molding error α of the vertex transmission refractive power P of the optical lens 20 predicted by the above formula (2) or formula (3) for each vertex transmission refractive power P in the design value of the optical lens 20. Here, the vertex transmission refractive power P at the design value of the optical lens 20 is the refractive index of the optical lens 20, and the central thickness between the design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20 is represented by When CT (unit: mm) is set and Ra and Rb (unit: mm) are used as the curvature radii of the design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20, the following expression (4) is satisfied. .

However, D1 = (n−1) × 1000 / Ra,
D2 = (n−1) × 1000 / Rb.

  In FIG. 5, the refractive index n of the optical lens 20 is set to n = 1.699, and the values of the curvature radii Ra and Rb of the design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20 are as follows: From the value of the center thickness CT between the design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20, the vertex transmission refractive power P at the design value of the optical lens 20 is calculated using Equation (4). For each calculated vertex transmission refractive power P, the shape factor SP is calculated and displayed using equation (1). It can be seen that the absolute value of the shape factor SP approaches 1 as the absolute value of the vertex transmission refractive power P in the design value of the optical lens 20 increases.

  Further, in FIG. 5, a molding error α of the vertex transmission refractive power P of the optical lens 20 to be molded is calculated and predicted using the formula (3), and the value of the predicted molding error α is calculated as an optical value. Displayed for each vertex transmission refractive power P at the design value of the lens 20. The predicted value of the molding error α is a value that is very close to the value of the molding error β (unit D (diopter)) of the vertex transmission refractive power P of the optical lens 20 measured by experiment. According to FIG. 6 which compares this predicted molding error α value with the experimentally measured molding error β value, these predicted molding error α value and measured molding error β value However, it turns out that the increase / decrease tendency substantially corresponded with respect to the vertex transmission power P in the design value of the optical lens 20 is shown.

  Therefore, the first use surface 16A of the upper mold 11 in the mold 10 shown in FIG. 1 is used by using the correction information corresponding to the molding error α of the vertex transmission refractive power P of the optical lens 20 predicted as described above. And the second usage surface 16B of the lower mold 12 are corrected and designed. For example, a value that cancels the predicted molding error α (that is, the sign of the value of the molding error α) is applied to the entire second surface 16B of the lower mold 12 designed as a design curved surface on the second surface 22 of the optical lens 20. The inverted value) is added as correction information in the axial direction of the lower mold 12, and the second usage surface 16B of the lower mold 12 is corrected and designed.

In this correction, if the refractive index of the optical lens 20 is n, the surface refractive power L (unit D (diopter)) on the lens curved surface (first surface 21, second surface 22) of the optical lens 20 and the lens curved surface thereof. Since the relationship of the following equation (5) is established with the radius of curvature R (unit m), the unit is unified between the predicted molding error α and the second usage surface 16B of the lower mold 12. After that, the above-described addition for correction is executed.
L = (n-1) / R (5)

  In addition, as described above, the reason for performing correction on the second usage surface 16B of the lower mold 12 instead of the first usage surface 16A of the upper mold 11 is that the lower mold 12 is common to the various optical lenses 20. The number of use surfaces to be corrected is smaller than that of the upper mold 11, and the curvature radius Rb of the second surface 22 of the optical lens 20 formed by the second use surface 16B of the lower mold 12 is changed. This is because the influence on the first surface 21 of the optical lens 20 is considered to act uniformly.

With the configuration as described above, the following effects (1) to (4) are achieved according to the above embodiment.
(1) Based on the shape factor SP that defines the shapes of both design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20, the molding error α of the vertex transmission refractive power P of the molded optical lens 20 is predicted. The correction information corresponding to the predicted molding error α is used to correct and design at least one of the first usage surface 16A of the upper mold 11 and the second usage surface 16B of the lower mold 12 in the molding die 10. Therefore, even when the optical lens 20 is deformed when the optical lens 20 is molded from the mold 10, the optical lens 20 having a desired transmission refractive power at the vertex O can be molded. .

  (2) Based on the shape factor SP that defines the shapes of both design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20, the molding error α of the vertex transmission refractive power P of the molded optical lens 20 is predicted. Therefore, it is not necessary to test-mold the optical lens with the mold 10 and measure the shape of the molded curved surface of the test-molded optical lens, so that the optical lens 20 having a desired transmission refractive power at the vertex O can be efficiently used. Can be molded.

  (3) A molding error of the vertex transmission refractive power P of the optical lens 20 to be molded by taking into account the shapes of both design curved surfaces on the first surface 21 and the second surface 22 of the optical lens 20 simultaneously using the shape factor SP. Since α is predicted, even if the curvatures of the design curved surfaces of the first surface 21 and the second surface 22 of the optical lens 20 are significantly different, the mold 10 based on the molding error α predicted as described above. The upper mold 11 and the lower mold 12 can be corrected with high accuracy.

  (4) Even when the optical lens 20 is deformed when the optical lens 20 is molded from the molding die 10, the shapes of both design curved surfaces on the first surface 21 and the second surface 22 of the optical lens 20 are the same. Based on the prescribed shape factor SP, the molding error α of the vertex transmission refractive power P of the optical lens 20 to be molded is predicted, and the upper mold 11 and the lower mold 12 of the mold 10 are corrected and designed. The optical lens 20 having a desired vertex transmission refractive power P can be molded.

As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.
For example, in the present embodiment, the optical lens 20 is manufactured by molding using the casting method. However, the present invention can be applied to manufacturing the optical lens 20 by a manufacturing method other than the casting method. . Specifically, when directly cutting and polishing a plastic optical lens, it is applied to cutting surface shape data correction in grinding processing, and shape correction and refractive power correction of a polishing tool (polishing dish) in polishing processing. Further, it can be applied to correction of a heat softening mold.

  Moreover, although the case where the shaping | molding die was glass was described in the said embodiment, this invention is applicable also to the case of shaping | molding with another shaping | molding die with a high heat shrinkage rate, for example, a metal mold | die.

  Further, in the above-described embodiment, correction is performed on the second usage surface 16B of the lower mold 12; however, the first usage surface 16A of the upper mold 11 and the second usage surface 16B of the lower mold 12 are described. Both, or the first use surface 16A of the upper mold 11 may be corrected using correction information corresponding to the predicted molding error α in the vertex transmission refractive power P of the optical lens 20.

1 is a side cross-sectional view showing a mold having an upper mold and a lower mold manufactured by carrying out an embodiment of a mold designing method according to the present invention. It is a sectional side view which shows the optical lens shape | molded with the shaping | molding die of FIG. It is a flowchart which shows the manufacture procedure of the optical lens (plastic lens) using the shaping | molding die of FIG. It is a flowchart which shows the manufacture procedure of the upper mold and lower mold of FIG. The curvature radius of each design curved surface on the first surface and the second surface of the optical lens shown in FIG. 2, the shape factor in the design value of the optical lens, and the predicted molding error of the vertex transmission refractive power of the molded optical lens It is a chart which shows etc. for every vertex transmission refracting power in the design value of the said optical lens. FIG. 6 is a graph showing a comparison between the predicted molding error α in the vertex transmission refractive power of the optical lens to be molded and the molding error β of the vertex transmission refractive power of the optical lens measured by experiment, displayed in FIG. 5. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 11 Upper mold 12 Lower mold 16A 1st use surface 16B 2nd use surface 20 Optical lens 21 1st surface 22 2nd surface Ra, Rb Curvature radius SP Shape factor O Vertex α Molding error

Claims (3)

A molding die for molding an optical lens in which the radius of curvature of the vertex of the first surface is Ra and the radius of curvature of the vertex of the second surface is Rb, for molding the first surface of the optical lens In a mold design method for designing a mold having an upper mold having a first molding surface and a lower mold having a second molding surface for molding the second surface of the optical lens,
When designing the curved surfaces of the first molding surface of the upper mold and the second molding surface of the lower mold, the molding is performed to correct the molding error α due to the transmission refractive power molding at the apex of the optical lens to be molded. A curved surface in which at least one molding surface of the first molding surface of the upper mold and the second molding surface of the lower mold is corrected using the correction information, with a value that cancels the error α as correction information. A design method for a molding die , wherein the curved surfaces of the first molding surface and the second molding surface are designed so as to have a curved surface shape different from a design curved surface of the optical lens .
However,
α = [{A × (Ra × SP) 1/2} / {(n−1) × 1000}]
− [{A × (Rb × SP) 1/2} / {(n−1) × 1000}]
And
SP = (Rb + Ra) / (Rb−Ra)
A is, SP is the refractive index of the first surface and a second surface shape factor defining the shape of the design curved surface of, n represents the optical lens of the optical lens, A is that determined Ri by the material of the optical lens It is a coefficient. A molding die for molding an optical lens in which the radius of curvature of the vertex of the first surface is Ra and the radius of curvature of the vertex of the second surface is Rb, for molding the first surface of the optical lens In a mold manufacturing method for manufacturing a mold having an upper mold having a first molding surface and a lower mold having a second molding surface for molding the second surface of the optical lens,
When the upper mold and the lower mold are obtained by processing glass blanks, correction information for correcting the molding error α in order to correct the molding error α due to transmission refractive power molding at the apex of the optical lens to be molded is correction information And at least one of the first molding surface of the upper mold and the second molding surface of the lower mold is a curved surface corrected using the correction information, and the optical lens is designed. The manufacturing method of the shaping | molding die characterized by processing the said glass blanks so that it may become a curved surface shape different from a curved surface .
However,
α = [{A × (Ra × SP) 1/2} / {(n−1) × 1000}]
− [{A × (Rb × SP) 1/2} / {(n−1) × 1000}]
And
SP = (Rb + Ra) / (Rb−Ra)
A is, SP is the refractive index of the first surface and a second surface shape factor defining the shape of the design curved surface of, n represents the optical lens of the optical lens, A is that determined Ri by the material of the optical lens It is a coefficient. A molding die for molding an optical lens in which the radius of curvature of the vertex of the first surface is Ra and the radius of curvature of the vertex of the second surface is Rb, for molding the first surface of the optical lens In a mold having an upper mold having a first molding surface and a lower mold having a second molding surface for molding the second surface of the optical lens,
A correction information is a value that cancels the molding error α in order to correct the molding error α due to molding of the refracting power at the apex of the optical lens to be molded, and the first molding surface of the upper mold and the second mold of the lower mold. A molding die characterized in that at least one of the molding surfaces is a curved surface corrected by using the correction information and has a curved surface shape different from a design curved surface of the optical lens .
However,
α = [{A × (Ra × SP) 1/2} / {(n−1) × 1000}]
− [{A × (Rb × SP) 1/2} / {(n−1) × 1000}]
And
SP = (Rb + Ra) / (Rb−Ra)
A is, SP is the refractive index of the first surface and a second surface shape factor defining the shape of the design curved surface of, n represents the optical lens of the optical lens, A is that determined Ri by the material of the optical lens It is a coefficient.

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