KR20130018590A - Method for estimating the degree of molding difficulty of aspherical glass mold lens and method for designing lens system including aspherical glass mold lens - Google Patents

Abstract

PURPOSE: A molding degree prediction method of an aspherical surface glass mold lens, and a design method of a lens system including the aspherical surface glass mold lens are provided to easily predict a molding degree from lens data including a rotational symmetry formula of an aspherical surface, thereby changing the aspherical surface. CONSTITUTION: Lens data including rotational symmetry aspherical surface data of an R1 surface and an R2 surface is inputted(S11). Slopes of the R1 surface and the R2 surface are calculated by differentiating an aspherical surface formula of the R1 and R2 surfaces(S12). The slopes of the R1 surface and the R2 surface are divided, and a slope rate is obtained(S13). [Reference numerals] (AA) Start; (BB,CC) End; (S11) Inputting(updating) aspherical surface data of an R1 surface and an R2 surface; (S12) Obtaining a slope equation dR1/2; (S13) Obtaining a slope equation d'R1/2; (S14) Is an inflection point exist in the slope equation dR1/2; (S15) Is an inflection point exist in the slope equation d'R1/2; (S16) Determining that a molding degree is low; (S17) Warning than the molding degree is high; (S18) Redesigning the aspherical surface data; (S19) Designed?; (S20) Null lens production, multi-stage press, Junction sleeve, corrective polishing

Description

METHODS FOR ESTIMATING THE DEGREE OF MOLDING DIFFICULTY OF ASPHERICAL GLASS MOLD LENS AND METHOD FOR DESIGNING LENS SYSTEM INCLUDING ASPHERICAL GLASS MOLD LENS}

TECHNICAL FIELD This invention relates to the method of predicting the molding difficulty at the time of mold shaping an aspherical glass lens, and the design method of the lens system containing an aspherical glass mold lens.

Background Art Conventionally, the moldability of a glass mold lens (hereinafter referred to as MO lens) has been judged by an empirical method such as whether it is a base material, a center thickness, a lens diameter, the presence or absence of a land, or a meniscus shape. For example, when the convex meniscus lens of the same center thickness is the same as a copper base material, it is said that the smaller the diameter of a lens is, the better surface shape is obtained.

Japanese Patent Publication No. 61-32263

However, in the field of press molding, it is a situation that bad aspherical MO lenses of very high production yield are frequently not met with the rule of thumb. The manufacturing process of an aspherical MO lens includes a shape specification (n (base material) of an aspherical lens in which a client (for example, a camera (lens) maker) determines a shape for an orderer (for example, a mold maker) based on a lens design). , r (curvature radius), d (thickness), data including a rotationally symmetric aspherical shape, and nrd-spherical data) are passed, and the orderer is concerned with forming an aspherical MO lens having a shape that is faithful to the shape specification. The same is true when the order is part of a camera maker's statement. In such a relationship, even if the moldability of the aspherical MO lens received is poor, and the manufacturing yield is poor, on the orderer's side which molds a mold lens using various press machines, the response cannot be made at all (or almost). In other words, even if the shape is difficult to form (poor manufacturing yield), there was no situation in which the orderer requested a change in the aspherical shape on the orderer's side or the grounds for the change request. And it is difficult for the lens system containing the aspherical MO lens which is difficult to shape | mold to obtain stable high optical performance as a result. According to the present inventors, the biggest problem is that, in the past, there is no clue as to what caused the good or bad moldability of the aspherical MO lens, and it has been judged only by empirical methods.

An object of the present invention is to predict a molding difficulty of an aspherical MO lens without a conventional clue, and to obtain a method of predicting molding difficulty that becomes a clue that requires a change in the design shape itself of an aspherical MO lens. In addition, the present invention, in the design of a lens system including an aspherical lens, when a design result containing an aspherical MO lens that is difficult to mold, the design method that can warn the difficulty of molding and promote the change of the design itself It aims to get (program).

The present inventors have found that the strain stress applied to the glass at the time of molding is influenced by the surface shape, the strain stress can be classified into agglomeration and divergence, and when the strain stress is agglomeration, the molding is easy. Based on the assumption that it is difficult, and therefore, to predict the aggregation and divergence of the strain stress, it is possible to predict the difficulty of molding aspheric shape. It was tried and completed this invention.

This invention is the rotation of the R1 surface and the R2 surface in the form of the method of predicting the shaping | molding difficulty of the aspherical glass mold lens which made at least one of R1 surface and R2 surface the rotationally symmetric aspherical surface represented by the following aspherical formula (1). Inputting lens data including symmetric aspheric data; Calculating slopes of the R1 and R2 surfaces by differentiating the aspherical equations (1) of the R1 and R2 surfaces once; Dividing one of the inclination of the R1 plane and the inclination of the R2 plane by the other to obtain an equation of the inclination ratio that is an index of the molding difficulty; It characterized in that it comprises a.

[ Equation 1 ]

In the method of predicting the molding difficulty of the aspherical glass mold lens of the present invention, the expression of the inclination ratio between the R1 and R2 surfaces may be further differentiated once or more, and the differential expression may be used as an index of the molding difficulty.

More specifically, whether the inflection point is included in the inclination ratio of the R1 plane and the R2 plane or the expression of the same inclination ratio once or more is used as an index of the molding difficulty. The case where there is no inflection point can be predicted to be for shaping | molding.

In the form of a lens system design method comprising an aspherical glass mold lens having at least one of the R1 surface and the R2 surface as a rotationally symmetric aspherical surface represented by the following aspherical formula (1), R1 surface and R2 during design Inputting lens data comprising said rotationally symmetric aspherical data of a surface; Calculating slopes of the R1 and R2 surfaces by differentiating the aspherical equations (1) of the R1 and R2 surfaces once; Dividing one of the inclination of the R1 plane and the inclination of the R2 plane to the other to obtain an equation of the inclination ratio; Making the formula of the slope ratio an index of the molding difficulty of the aspherical glass mold lens; It characterized in that it comprises a.

In the design method of the lens system including the aspherical glass mold lens of the present invention, the expression of the inclination ratio between the R1 surface and the R2 surface can be differentiated once more or more, and the differential expression can be used as an index of molding difficulty.

In the step of determining the molding difficulty, if the inflection point is included as an index of the molding difficulty, whether or not the inflection point is included in the expression of the inclination ratio of the R1 plane and the R2 plane or the expression of the same inclination ratio one or more times. The case where it is difficult for shaping | molding and there is no inflection point can be estimated that it is for shaping | molding.

The step of determining the molding difficulty may also include a step of warning when it is determined that molding is difficult.

In the method of designing a lens system including the aspherical glass mold lens of the present invention, an inflection point is included in an equation in which the inclination ratio of the R1 plane and the R2 plane, or the derivative of the same inclination ratio, is further differentiated one or more times in determining the molding difficulty. In this case, as long as the aspherical data is redesigned and the solution of the redesign exists, the inflection point in the equation where the inclination ratio of the R1 plane and the R2 plane or the derivative of the same inclination ratio is different one or more times again. You can continue the design until it is gone.

When the redesign of the aspherical data does not exist, the solution of the redesign does not exist. One or more of the methods of manufacturing a null lens, employing a multi-stage press, applying a side connection sleeve to a press, and correcting and polishing a molded lens Adoption can be decided.

According to the present invention, the molding difficulty of the aspherical MO lens can be easily estimated from the lens data including the rotationally symmetric aspherical formula. For this reason, the prediction of the molding difficulty can be fed back to the lens design section to promote the change of the aspherical shape, and can be replaced with an aspherical MO lens which is easy to mold. In addition, in the lens design stage, if the warning of the molding difficulty of the aspherical MO lens or if the redesign is continued as long as there is a redesign solution in the aspherical formula, the aspherical MO lens (e.g. It is possible to design a lens system, and as a result, a stable high optical performance lens system can be obtained at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross sectional view of an image when a glass sphere is pressed into a vertical mold and molded into a corba-mounted biconvex lens.
2A and 2B are graphs showing a coordinate system of a design state and a press state of a lens shape.
3 is a graph showing an example of the inclination distribution of the entrance face (R1 face) and the exit face (R2 face) of the lens.
4 is a diagram illustrating the distribution shape and formability of the inclination ratio dR _1/2 between the R1 and R2 surfaces of the lens.
5A and 5B are cross-sectional views illustrating examples of lens shapes of sample lens 1 and sample lens 2. FIG.
6 is a comparative diagram showing the distribution shape of the inclination ratio (dR _1/2 ) of the sample lens 1 and the sample lens 2, the predictability of formability, and the actual molding result of the R1 surface.
7 is a comparative diagram showing the distribution shape of the inclination ratio (dR _1/2 ) of the sample lens 1 and the sample lens 3, the predictability of moldability, and the actual molding result of the R1 surface.
FIG. 8 is a graph showing a shape example of d'R _{1/2 obtained} by differentiating the expression of the slope ratio dR _1/2 again.
9 is a graph showing another configuration example of d'R _1/2 .
FIG. 10 shows the distribution shape, formability prediction, and actuality of d'R _{1/2 obtained} by differentiating the inclination ratio (dR _1/2 ) between the R1 and R2 surfaces of the sample lens 4, the sample lens 5, and the sample lens 6; It is a comparative diagram which shows the shaping result of the R1 surface.
FIG. 11 is a comparison diagram showing a specific example of the biconvex MO lens of the double-sided aspherical surface. FIG.
FIG. 12 is a comparative view showing a specific example of a biconcave MO lens of double-sided aspherical surface. FIG.
FIG. 13 is a comparative diagram showing a specific embodiment of the convex meniscus MO lens of the double-sided aspherical surface. FIG.
FIG. 14 is a comparative view showing a specific example of a concave meniscus MO lens having a double-sided aspherical surface. FIG.
FIG. 15 is a comparison diagram showing a specific example of a biconvex MO lens of a single aspherical surface. FIG.
FIG. 16 is a comparison diagram showing a specific embodiment of the biconcave MO lens of the one-sided aspherical surface. FIG.
17 is a comparison diagram showing a specific embodiment of the convex meniscus MO lens of the single-sided aspherical surface.
FIG. 18 is a comparative view showing a specific embodiment of a concave meniscus MO lens of one-sided aspherical surface. FIG.
19 is a flowchart illustrating one embodiment of a method for designing a lens system according to the present invention.

FIG. 1: is an image figure at the time of pressing the glass sphere G by the upper and lower shaping | molding dies M1 and M2, and shape | molding with a cobar mounting biconvex lens. When strain stress is given to glass sphere G by shaping | molding die M1 and M2, glass moves to a horizontal direction (diameter direction). At this time, if the spaces (cylindrical and prismatic) sides between the shaping molds M1 and M2 are open, the stress is diverged, so that it is not a bibar-convex lens attached to the bar (upper right in Fig. 1). On the other hand, if there is a cylindrical isoform W on the space side between the forming dies M1 and M2, the strain stress generated on the glass is the same as the space of the die W and forming dies M1 and M2. Because it is confined inside, it becomes a Cova mounting biconvex lens (lower right in FIG. 1). This embodiment proposes about the index of the rotationally symmetric aspherical shape of the aspherical MO lens by which strain stress is confined as shown in the right side of FIG.

The molding difficulty prediction method of the aspherical MO lens according to the present embodiment includes a rotationally symmetric aspherical surface represented by the following formula (1) on at least one surface (at least one of the R1 surface and the R2 surface) of the target MO lens: On the premise that

[ Equation 1 ]

In Equation 1, R, K, a, b, c, d... Are constants, and y and x are the radius and displacement of the lens, respectively.

In addition, when the value of x in arbitrary point y _i is set to x _i , Formula (1) is transformed into the following formula (1 ').

[ Equation 1 ' ]

In addition, for the y _i, when the minute difference from a δ min y _{i +} δ, equation (1) is a "to the equation (1) ''.

[ Equation 1 '' ]

This embodiment is based on the premise of receiving and inputting aspherical data of an aspherical MO lens to be molded. The data is provided from the orderer (lens maker) to the orderer (mold maker), and the data is sent to the lens design program / device.

2A is a coordinate system showing the above lens shape. In the press molding of the convex (meniscus) lens, the convex surface is formed into a lower mold, and for convenience, x and y are rewritten as in FIG. 2A as shown in FIG. 2B.

From FIG. 2B, the inclination distribution dR of the lens shape is differentiated by Equation 1 ″ once, and is given by the following Equation 2.

& Quot; (2 ) & quot ;

Thus, R1 surface (first surface, the incident surface) gradient distribution (dR ₁₎ and, R2 if the slope distribution of the (second surface, the exit surface) (dR _2), the following equation (2) ') and (2' It is represented by '.

[ Equation 2 ' ]

[ Equation 2 '' ]

An example of plotting these gradient distributions dR ₁ and gradient distributions dR ₂ with respect to y, that is, the radius of the convex meniscus lens, is shown in FIG. 3.

In this embodiment, in order to predict the molding difficulty of an aspherical MO lens, the inclination ratio (dR _1/2 ) which normalized the inclination of the R1 surface to the inclination of the R2 surface is used. That is, the slope ratio dR _1/2 is defined as Equation 3 after dividing Equation 2 'by Equation 2''.

& Quot; (3 ) & quot ;

In Equation 3, when y _i and δ are the same in the R1 plane and the R2 plane, Equation 3 becomes Equation 4.

[ Equation 4 ]

Since the inclination ratio (dR _1/2 ) obtained in the equation (4) is a value obtained by standardizing the inclination of the R1 plane by the inclination of the R2 plane, the inclination ratio (dR _1/2 ) is an index of the aggregation and divergence of the deformation stress or the holding stress generated during press molding. It can be seen that. That is, for the y _i, the slope ratio (dR _1/2) of the outer diameter direction smile δ minute difference from y _{i +} δ is, has the following relationship between the stress and strain or not stress, as a result of the R1 surface It is expected to affect shape stability (easiness of molding, difficulty of molding).

a) The slope ratio (dR _1/2 ) increases monotonically = the slope of the R1 plane becomes larger toward the outer circumferential direction = stress cohesion

→ R1 surface shape tends to be stable

b) The slope ratio (dR _1/2 ) is monotonically reduced = the relative slope of the R1 plane decreases toward the outer circumferential direction = stress divergence

→ R1 surface shape tends to be unstable

c) The slope ratio (dR _1/2 ) has an inflection point = has an inflection point of cohesion and divergence of stress

→ R1 surface shape tends to be unstable

In this manner, even if the same convex meniscus lens is an aspherical shape in which the inclination ratio dR _1/2 is monotonically increased, a stable lens shape is obtained, and when the monotonic decrease and an inflection point are provided, the lens shape is predicted to be unstable. 4 lists the above relations.

FIG. 5 shows an example of a cross-sectional shape of the convex meniscus lenses of Samples 1 and 2, and FIG. 6 shows the distribution shape of the inclination ratio (dR _1/2 ) of the Samples 1 and 2 and the formability prediction. And an example of the actual molding result are shown. Sample 1 in which the gradient ratio dR _1/2 monotonously increased was also good in the actual molding result of the R1 surface, whereas in Sample 2 in which the gradient ratio dR _1/2 was the inflection point, the actual molding of the R1 surface The results were found to be unstable and of low quality. 6 (and the same figure below), the shaping | molding result was recorded on the graph which shape | molded many sample lenses in the same shaping | molding form, and investigated the shape, The thing with little deviation in the graph of the actual shaping | molding result is shaping | molding. Good stability (high lens shape quality) and large variation indicate poor molding stability (bad lens shape quality).

7 shows the shape of the inclination ratio dR _1/2 by replacing the shape of the R2 surface with the shape of the R2 surface of the sample 1 without changing the shape of the R1 surface in the sample 2 and the same sample 2 of FIG. The sample 3 in which is changed to monotone increase is shown an example of the shape of each inclination ratio dR _1/2 , the predictability of moldability, and the actual molding result. Although the shaping result of the R1 surface is a problem, it is confirmed that the formability is improved by changing the shape of the R2 surface (change the shape of dR _1/2 ). That is, the shape of the R2 surface is closely involved in the formability of the R1 surface.

As described above, the shape of the inclination ratio (dR _1/2 ) is obtained by taking the ratio of the equation of the rotationally symmetric aspherical expression of the R1 plane of the aspherical surface MO lens once, and the expression of the expression of the rotation symmetry aspherical expression of the R2 surface once. On examination, it turned out that moldability can be judged. On the other hand, the distribution shape of the inclination ratio dR _1/2 has a complicated shape, and it has also been found that there are cases in which sufficient moldability cannot be determined only by the shape of the inclination ratio dR _1/2 . 8 shows an example of the shape of such an inclination ratio dR _1/2 .

In such a case, the slope ratio dR _1/2 of Equation 4 above is further differentiated ((differentiation of Equation 1 '' twice) to obtain d'R _1/2 of Equation 5 below, and the shape By judging, moldability can be predicted.

[ Equation 5 ]

FIG. 9 shows a shape example of d'R _{1/2 obtained} by interestingly formulating the inclination ratio dR _1/2 of FIG. 8. It was expected that d'R _1/2 had a clear inflection point and had low molding stability, and when actually molded, it was as expected.

FIG. 10 shows an example of the shape of d'R _1/2, the predictability of moldability, and the actual molding result. Sample 5 (same as the previous sample 1) in which d'R _1/2 monotonically increased, while the actual molding result of the R1 plane was also good, while sample 4 (the previous sample 2) had an inflection point in dR _1/2 . And Sample 6, it was confirmed that the actual molding result of the R1 surface was unstable and the production yield was bad.

The discussion using the aspherical convex meniscus MO lens as an example has been confirmed to hold in both convex, concave, convex meniscus and concave meniscus. Moreover, not only a double-sided aspherical MO lens but also a single-sided aspherical MO lens is established. In addition, it does not matter whether a base material, a center thickness, a lens diameter, the presence or absence of a land, the presence or absence of a coat, the material, and the kind of press machine.

Hereinafter, a double-sided aspherical surface and a single-sided aspherical MO lens including a specific aspherical surface formula will be described with reference to a lens cross section, a shape of dR _1/2 , a shape of d'R _1/2 , and formability prediction. 11 to 18, "E ± a" means "x10 + ^a ".

11, 12, 13, and 14 are two-sided aspherical MO lenses, which are specific examples of a biconvex lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens.

Aspheric data of three double-sided aspherical biconvex MO lenses is described in FIG. 11. Each parameter (R, k, a, b, c, d) of the aspherical surface on the R1 surface is the same value, and each parameter (R, k, a, b, c, d) of the aspherical surface on the R2 surface Is designed as shown in FIG.

In FIG. 11, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted to be molded in the first derivative and the second derivative. In the figure, the embodiment in the middle has no inflection point in dR _1/2 , and is predicted to be for molding, and the implementation in which the inflection point is confirmed for the first time in d'R _1/2 is confirmed and is difficult to mold. Yes. In addition, although the inflection point was confirmed in dR _1/2 in the same figure, it predicted that it was difficult to shape | molded, but it evaluates also about d'R _1/2 , and confirms an inflection point.

Aspheric data of three double-sided aspherical biconcave MO lenses is described in FIG. 12. Each parameter (R, k, a, b, c, d) of the aspherical surface on the R1 surface is the same value, and each parameter (R, k, a, b, c, d) of the aspherical surface on the R2 surface Is designed as shown in FIG.

In FIG. 12, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted to be molded in the first derivative and the second derivative. In addition, in the same figure, the Example of the middle does not have an inflection point in dR1 _{/ 2} , and it is estimated that it is for shaping | molding, and the Example which an inflection point was confirmed for the first time in d'R1 _{/ 2} , and was found to be difficult to shape | mold to be. In addition, although the inflection point was confirmed in dR _1/2 in the same figure, it predicted that it was difficult to shape | molded, but it evaluates also about d'R _1/2 , and confirms an inflection point.

In Fig. 13, aspherical data of three double-sided aspherical convex meniscus MO lenses is described. Each parameter (R, k, a, b, c, d) of the aspherical surface on the R1 surface is the same value, and each parameter (R, k, a, b, c, d) of the aspherical surface on the R2 surface Is designed as shown in FIG.

In FIG. 13, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted for molding in the first and second derivatives. In addition, in the same figure, the Example of the middle does not have an inflection point in dR _1/2 , and it is predicted that it is for shaping | molding, The Example in which the inflection point was confirmed for the first time in d'R _1/2 , and it was difficult to shape | mold. to be. In addition, although the inflection point was confirmed in dR _1/2 in the same figure, it predicted that it was difficult to shape | molded, but it evaluates also about d'R _1/2 , and confirms an inflection point.

In FIG. 14, aspherical data of three double-sided aspherical concave meniscus MO lenses are described. Each parameter (R, k, a, b, c, d) of the aspherical surface on the R1 surface is the same value, and each parameter (R, k, a, b, c, d) of the aspherical surface on the R2 surface Is designed as shown in FIG.

In FIG. 14, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted for molding in the first and second derivatives. In addition, in the same figure, the Example of the middle does not have an inflection point in dR1 _{/ 2} , and it is estimated that it is for shaping | molding, and the Example which an inflection point was confirmed for the first time in d'R1 _{/ 2} , and was found to be difficult to shape | mold to be. In addition, although the inflection point was confirmed in dR _1/2 in the same figure, it predicted that it was difficult to shape | molded, but it evaluates also about d'R _1/2 , and confirms an inflection point.

15, 16, 17, and 18 are specific embodiments of a biconvex lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens as a single-sided aspherical MO lens.

Aspheric data of three single-sided aspherical biconvex MO lenses is described in FIG. 15. While the R2 surface is formed into a spherical surface having a constant curvature, each parameter R, k, a, b, c, d of the aspherical surface on the R1 surface is designed as shown in FIG.

In FIG. 15, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted to be molded in the first derivative and the second derivative. In addition, in the middle example of FIG. 15, there is no inflection point in dR _1/2 , and it is predicted that it is for shaping | molding, The Example in which the inflection point was confirmed for the first time in d'R _1/2 , and it was predicted that it was difficult to shape | mold. to be. In addition, although the inflection point was confirmed in dR _1/2 in FIG. 15, the right Example predicted that it was difficult to shape | molded, but to d'R _1/2 The inflection point was also confirmed by evaluation.

Aspheric data of three single-sided aspherical biconcave MO lenses are described in FIG. 16. While the R2 surface is formed into a spherical surface having a constant curvature, each parameter R, k, a, b, c, d of the aspherical surface on the R1 surface is designed as shown in FIG.

In FIG. 16, in the left side example, dR _1/2 and d'R _1/2 do not have an inflection point, and it is the Example predicted for shaping | molding in a 1st derivative and a 2nd derivative. In addition, in the middle example of FIG. 16, there is no inflection point in dR _1/2 , and it is predicted that it is for shaping | molding, The Example in which the inflection point was confirmed for the first time in d'R _1/2 , and it was predicted that molding was difficult to be. In addition, although the inflection point was confirmed in dR _1/2 in FIG. 16, it predicted that it was difficult to shape | molded, but d'R _1/2 was also evaluated and the inflection point is confirmed.

In FIG. 17, aspherical data of three single-sided aspherical convex meniscus MO lenses is described. While the R2 surface is formed into a spherical surface having a constant curvature, each parameter R, k, a, b, c, d of the aspherical surface on the R1 surface is designed as shown in FIG.

In FIG. 17, the examples on the left side are examples in which dR _1/2 and d'R _1/2 do not have inflection points, and are predicted to be molded in the first derivative and the second derivative. In addition, in the middle example of FIG. 17, there is no inflection point in dR _1/2 , and it is predicted that it is for molding, and an example in which the inflection point is confirmed for the first time in d'R _1/2 is confirmed to be difficult to mold. to be. In addition, although the inflection point was confirmed in dR _1/2 in FIG. 17, it predicted that it was difficult to shape | molded, but it evaluates also about d'R _1/2 , and confirms an inflection point.

18 shows aspherical data of three single-sided aspherical concave meniscus MO lenses. While the R2 surface is formed into a spherical surface having a constant curvature, each parameter R, k, a, b, c, d of the aspherical surface on the R1 surface is designed as shown in FIG.

In FIG. 18, the examples on the left side do not have inflection points in both dR _1/2 and d'R _{1/2, and} are examples which are predicted to be molded in the first derivative and the second derivative. In addition, in the middle example of FIG. 18, there is no inflection point in dR _1/2 , and it is estimated that it is for shaping | molding, and the Example in which the inflection point was confirmed for the first time in d'R _1/2 , and it was difficult to shape | mold to be. In addition, although the inflection point was confirmed in dR _1/2 in FIG. 18, it predicted that it was difficult to shape | molded, but also evaluates about d'R _1/2 and confirms an inflection point.

In the embodiment of Fig. 11 to Fig. 18, both dR _1/2 and d'R _1/2 have "the inflection point" as the sole criterion. From these examples, the primary determination of moldability is possible only by whether or not the inflection point is in dR _1/2 , but the determination material is added to whether or not the inflection point is in d'R _1/2 . Can be. In particular, it was confirmed that the presence or absence of the inflection point of the expression of the second derivative has universality which can judge the good or bad moldability regardless of the lens shape. In addition, when the presence or absence of an inflection point is not clear by the expression of two derivatives, the presence or absence of an inflection point may be investigated by the expression of three or more derivatives.

According to the prediction method of the difficulty of molding according to the present embodiment, based on the prediction result (prediction that molding is difficult), it is possible to propose based on the request for changing the aspherical shape from the manufacturing site to the design section. In addition, the quality assurance section can contribute to the examination of the sorting method of the molded lens and pre-arrangement of the null lens, etc., and the sales section can contribute to the bargaining price in consideration of low manufacturing yield and selection cost. As a result, production with high production yield, delivery at a reasonable price, production without confusion or delay in delivery is possible.

In the lens design program, it is also possible to adopt the method for predicting the molding difficulty according to the present invention. In general, in the lens design performed by the automatic design program, the designer inputs a focal length, the number of lenses, the allowable aberration, whether the aspherical surface is introduced, the number of points, and the like before starting the automatic design. As a result of the automatic design, using the aspherical surface data of the front and back, the slope ratio (dR _1/2 ) and the slope ratio (d'R _1/2 ) are calculated using the aspherical surface data of the front and rear surfaces. When predicted and displayed, the designer can be warned that there is a difficulty in formability, and the designer can change the design based on the warning. Or, during the automatic design program, undesirable tilt ratio (dR _1/2 ) and tilt ratio (d'R _1/2 ) do not occur (preferred tilt ratio (dR _1/2 ) and tilt ratio (d'R). such that the combination _{of 2))} may include a subroutine for determining the aspherical surface shape.

19 is a flowchart illustrating an example of a lens design method according to the present invention.

First, during the design of the lens system, lens data including the rotationally symmetric aspherical data of the R1 plane and the R2 plane is input (step S11).

Subsequently, the inclination of the R1 plane and the R2 plane is respectively calculated by differentiating the input aspheric data of the R1 plane and the R2 plane once, and one of the inclinations of the R1 plane and the slope of the R2 plane is divided to the other side to determine the slope ratio. The formula dR _1/2 is obtained (step S12).

Next, the expression dR _1/2 of the tilt ratio obtained in step S12 is further differentiated once to obtain a tilt equation d'R _1/2 (step S13).

Equation dR _1/2 of the slope ratio obtained in step S12 and Slope expression d'R _1/2 obtained in step S13 When none of the inflection points exist (step S14: NO, step S15: NO), it is determined that the molding difficulty of the aspherical lens is low (easily moldable) (step S16), and the processing is finished.

On the other hand, when an inflection point exists in either of the formula dR _1/2 of the tilt ratio obtained in Step S12 and the slope formula d'R _1/2 obtained in Step S13 (Step S14: YES, Step S15: YES), A warning is given that the molding difficulty is high (step S17), and the aspheric data is redesigned (step S18).

If the aspherical surface data redesigned in step S18 has been solved (step S19: YES), the already inputted aspherical surface data is replaced with the redesigned aspherical surface data, and the processes of steps S12 to S19 are repeated. . That is, as long as the aspherical data without inflection point is obtained in the slope ratio dR _1/2 and the slope ratio d'R _{1/2 as} long as the design solution exists in the redesigned aspherical data (step S19: YES). The lens design of the lens system including the aspheric lens (which is easy to mold) having low molding difficulty is repeated (Step S14: NO, Step S15: NO).

When there is no design solution in the aspheric data redesigned in step S18 (the design solution without inflection points in the tilt ratio (dR _1/2 ) and the slope ratio (d'R _1/2 ) does not exist) (step S19: NO ), One or more methods of manufacturing a null lens, employing a multi-stage press, applying a side connecting sleeve to a press type, or correcting polishing of a molded lens are determined (step S20), and the processing is finished.

In addition, although the inclination ratio (dR _1/2 ) which divided the inclination of the R1 plane by the inclination of the R2 plane was used in the above embodiment, the same judgment can be made even if the inclination ratio which divided the inclination of the R2 plane by the inclination of the R1 plane is used. have. In addition, in each Example of FIG. 11-14, although the value of the R1 surface was unified about three Example, and the example which changed the value of the R2 surface was shown, it is not limited to this. In addition, in the said Example, although the example which dR _1/2 increases and predicted that it was for shaping | molding, this invention is not limited to this and can apply this invention also when it decreases.

In the above embodiment, the rotationally symmetric aspherical data is provided from the lens maker to the mold maker, but may be performed from the camera maker's design section to the manufacturing section. In addition, the case where aspherical data moves within the lens design program / device is also included in the provision of the data.

In addition, the glass raw material used in order to shape the glass lens described in the above embodiment combines the raw materials of the glass in a predetermined ratio, obtains a dissolution, homogeneous and clarification process, and supplies the molten glass to the molding die and cools it. The molten glass supplied above the mold was molded into a predetermined shape (a spherical preform, a flat gob, and an approximate preform approximated to the shape of the aspherical lens to be obtained) to obtain a glass material.

And the glass shape of the shaping | molding surface was transferred to the shaping | molding material by the precision press molding of the glass raw material by the press shaping | molding die which has the shaping | molding surface which applied the precision processing, and the lens was manufactured. At this time, the glass material is heated to a temperature exhibiting a viscosity of about 10 ⁶ to 10 ¹² dPa · s to perform precision press molding, and after cooling to a temperature exhibiting a viscosity of 10 ¹² dPa · s or more, the precision press molded article is press-molded. It was taken out from the mold.

Claims (10)

As a method of predicting the molding difficulty of an aspherical glass mold lens having at least one of R1 and R2 as a rotationally symmetric aspherical surface represented by the following aspherical formula (1),
Inputting lens data including said rotationally symmetric aspheric data of R1 plane and R2 plane;
Calculating slopes of the R1 and R2 surfaces by differentiating the aspherical equations (1) of the R1 and R2 surfaces once;
And dividing either one of the inclination of the R1 plane and the inclination of the R2 plane to the other, and obtaining an equation of an inclination ratio that is an index of the molding difficulty.
[Equation 1]

The method of claim 1, wherein whether the inflection point is included in the formula of the inclination ratio between the R1 and R2 planes is used as an index of the difficulty of molding, and the case where the inflection point is difficult to be molded and the case where there is no inflection point is for molding. Molding difficulty prediction method of aspherical glass mold lens. The method for predicting molding difficulty of an aspherical glass mold lens according to claim 1, wherein the expression of the inclination ratio between the R1 surface and the R2 surface is further differentiated one or more times, and the differential expression is an index of the molding difficulty. The method of claim 3, wherein whether the inflection point is included in the equation obtained by differentiating the inclination ratio of the R1 plane and the R2 plane one or more times is used as an index of the molding difficulty, and the case of the inflection point is difficult to mold and has no inflection point. Molding difficulty prediction method of aspherical glass mold lens which predicts the case for shaping | molding. A lens system design method comprising an aspherical glass mold lens having at least one of R1 and R2 as a rotationally symmetric aspherical surface represented by the following aspherical formula (1),
During design, inputting lens data including said rotationally symmetric aspheric data of R1 and R2 surfaces;
Calculating slopes of the R1 and R2 surfaces by differentiating the aspherical equations (1) of the R1 and R2 surfaces once;
Dividing one of the inclination of the R1 plane and the inclination of the R2 plane by the other and obtaining an equation of the inclination ratio;
A method of designing a lens system comprising an aspherical glass mold lens, characterized in that the inclination ratio formula is an index of the molding difficulty of the aspheric glass mold lens.

6. The method according to claim 5, wherein whether the inflection point is included in the formula of the inclination ratio between the R1 plane and the R2 plane is used as an index of the molding difficulty, and the case where the inflection point is difficult for molding and the case where there is no inflection point is for molding. A method of designing a lens system comprising an aspherical glass mold lens. The method of claim 5, wherein the expression of the inclination ratio between the R1 plane and the R2 plane is further differentiated one or more times, and the differential equation is used as an index of the molding difficulty, and the case of the inflection point is difficult to form and there is no inflection point. A method of designing a lens system comprising an aspherical glass mold lens for predicting that it is for molding. The lens system design method according to any one of claims 5 to 7, further comprising a step of warning when the molding difficulty is judged to be difficult in molding. The method according to any one of claims 5 to 8, wherein an inflection point is included in an equation in which the inclination ratio between the R1 plane and the R2 plane or the derivative of the same inclination ratio is different one or more times in the step of determining the molding difficulty. If present, redesign the aspherical data and, as long as there is a solution for the redesign, design the slope ratio of the R1 and R2 planes, or the derivative of the same slope ratio, one more time, until the inflection point disappears. Method of designing a lens system comprising an aspherical glass mold lens to continue. 10. The method according to claim 9, wherein when there is no solution for redesign even when redesigning the aspherical data, any one of manufacturing a null lens, employing a multi-stage press, applying a side connection sleeve to a press type, and correcting polishing of a molded lens The lens system design method containing the aspherical glass mold lens which determines adoption of the above method.

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