KR101625426B1 - 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

(Problem) A method of predicting the degree of molding difficulty of an aspherical MO lens in which the conventional clue does not exist is predicted, and a method of predicting the degree of molding difficulty, which leads to a change in the design shape itself of the aspherical MO lens, is demanded.
[MEANS FOR SOLVING PROBLEMS] A method for predicting a forming difficulty of an aspheric glass mold lens having a rotationally symmetric aspherical surface represented by an aspherical surface expression of at least one of an R1 surface and an R2 surface,
The slope of the R1 surface and the R2 surface is calculated by differentiating the aspherical formulas of the R1 surface and the R2 surface by one time, and based on the formula of the slope ratio obtained by dividing either the slope of the R1 surface or the slope of the R2 surface into the other A method of predicting the degree of molding difficulty of an aspherical glass mold lens for determining the degree of molding difficulty.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an aspherical glass mold lens,

The present invention relates to a method of predicting the degree of molding difficulty when molding an aspherical glass lens and a method of designing a lens system including an aspherical glass mold lens.

Conventionally, the formability of a glass mold lens (hereinafter referred to as an MO lens) has been judged by empirical techniques such as whether it is a glass material, a center thickness, a lens diameter, a presence of a land, or a meniscus shape. For example, a convex meniscus lens having a center thickness of about the same as that of a copper cylinder has been found to have a good surface shape with a smaller lens diameter.

Japanese Patent Publication No. 61-32263

However, in the field of press forming, it is a reality that a bad aspheric MO lens with a very low manufacturing yield is frequently encountered because it does not fit the empirical rule. The manufacturing process of the aspherical MO lens is carried out in such a manner that the shape specification (n (superfine)) of the aspherical lens whose shape is determined on the basis of the lens design for the owner (for example, a mold maker) , n (aspherical surface data), r (radius of curvature), d (thickness), and rotationally symmetric aspherical shape, and the recipient carries out shaping of the aspherical MO lens having a shape faithful to the shape specification. This is also the case when the order owner is a part of the camera maker. In such a relationship, even if the moldability of an aspherical MO lens ordered is poor and the production yield is poor, the correspondent can not (or rarely) cope with the molder using a molding machine using various press machines. That is, even if the shape is difficult to form (the manufacturing yield is poor), it has been the case that the buyer side requests the owner side to change the aspherical shape and there is no basis for the change request. In addition, it is difficult for a lens system including an aspherical MO lens to be difficult to form, as a result, to obtain stable high optical performance. According to the present inventors, the biggest problem is that there is no clue as to what causes the moldability of the aspheric MO lens to be good or bad at all, and it has been determined only by the empirical technique.

An object of the present invention is to obtain a method of predicting the degree of molding difficulty of an aspherical MO lens in which the conventional clue does not exist and a method of predicting the degree of molding difficulty which leads to a change in the design shape itself of the aspherical MO lens. Further, in the design of a lens system including an aspheric lens, when the design result includes an aspherical MO lens which is difficult to be molded, the present invention provides a design method which can warn the difficulty of molding, (Program) of the present invention.

The inventors of the present invention have found out that the deformation stress applied to the glass at the time of molding is influenced by the surface shape and that the deformation stress can be classified into cohesion and divergence, Based on the assumption that it is possible to predict the degree of difficulty of forming an aspherical shape if the difficulty and therefore the cohesion and divergence of the deformation stress can be predicted, it is possible to predict the molding difficulty from the aspheric equation to the surface, which is an index of the rotationally symmetric aspheric shape And the present invention was completed.

The present invention is characterized in that, in the form of a method for predicting the degree of molding difficulty of an aspheric surface 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 surface expression (1) Inputting lens data including symmetric aspherical surface data; Calculating the slopes of the R1 surface and R2 surface by differentiating the aspherical surface expression (1) of R1 surface and R2 surface by 1 time; Dividing one of a slope of the R1 surface and a slope of the R2 surface into the other, thereby obtaining an expression of a slope ratio serving as an index of the degree of molding difficulty; And a control unit.

[ Equation 1 ]

In the method of predicting the degree of molding difficulty of an aspherical surface molded lens according to the present invention, the formula of the slope ratio of the R1 surface and the R2 surface is again differentiated one or more times, and the sub-equation can be used as an index of the degree of molding difficulty.

More specifically, whether the inclination ratio of the R1 surface and the R2 surface or the expression of the dynamic gradient is further differentiated one or more times or not includes an inflection point is used as an index of the degree of molding difficulty, and if there is an inflection point, , And the case in which there is no inflection point can be predicted as molding.

The present invention is characterized in that, in the form of a design method of a lens system including an aspheric surface 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 surface expression (1) Inputting lens data including the rotationally symmetric aspherical surface data of the surface; Calculating the slopes of the R1 surface and R2 surface by differentiating the aspherical surface expression (1) of R1 surface and R2 surface by 1 time; Dividing one of a slope of the R1 surface and a slope of the R2 surface to obtain an equation of the slope ratio; Making the formula of the slope ratio an index of the degree of molding difficulty of the aspherical glass mold lens; And a control unit.

In the method of designing a lens system including the aspherical surface glass molded lens of the present invention, the formula of the slope ratio of the R1 surface and the R2 surface is further differentiated one or more times, and the slicing can be used as an index of the degree of molding difficulty.

In the step of determining the degree of molding difficulty, whether or not an inflection point is included in the equation obtained by further differentiating the expression of the inclination ratio of the R1 side and the R2 side or the expression of the dynamic gradient more than once is used as an index of the degree of molding difficulty, It can be predicted that molding difficulty and the case where there is no inflection point are for molding.

A step of warning when it is determined that molding is difficult in the step of determining the degree of molding difficulty.

In the method of designing a lens system including an aspheric surface glass molded lens of the present invention, an inflection point is included in a formula for differentiating the expression of the inclination ratio of the R1 face and the R2 face or the expression of the inclination ratio one more time in the step of judging the degree of molding difficulty The aspherical surface data is redesigned and the inflection point is calculated by dividing the expression of the slope ratio of the R1 surface and the R2 surface or the expression of the slope ratio by one or more times as long as there is a solution of the redesign You can continue designing until it disappears.

When there is no solution for the redesign even after the redesign of the aspherical surface data, there is no need to use any one or more of the following methods: manufacture of a null lens, adoption of a multi-stage press, application of a side connection sleeve in a press type, You can decide to hire.

According to the present invention, the molding difficulty of an aspherical MO lens can be easily predicted from lens data including a rotationally symmetric aspherical equation. As a result, the prediction of the difficulty of molding can be fed back to the lens designing section to promote the change of the aspherical shape and to change to the aspherical MO lens which is easy to mold. Further, in the lens designing stage, if the difficulty in molding of the aspherical MO lens is warned, or if the redesign is continued as long as there is a redesign in the aspherical form, the aspherical MO lens , It is possible to design a lens system, and as a result, a lens system with stable high optical performance can be obtained at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an image sectional view when a glass spherical body is pressed in an upper mold and a lower mold and molded with a corbar-mounted biconvex lens. Fig.
Figs. 2A and 2B are graphs showing a coordinate state of a lens state and a press state. Fig.
3 is a graph showing an example of a tilt distribution of an incident surface (R1 surface) and an exit surface (R2 surface) of the lens.
Fig. 4 is a view showing the distribution shape and formability of the slope ratio (dR1 _{/ 2} ) between the R1 surface and the R2 surface of the lens.
Figs. 5A and 5B are cross-sectional views showing examples of lens shapes of the sample lens 1 and the sample lens 2. Fig.
Fig. 6 is a comparative diagram showing the distribution shape of the slope ratio (dR1 _{/ 2} ) of the sample lens 1 and the sample lens 2, the formability prediction, and the actual molding result of the R1 surface.
Fig. 7 is a comparative diagram showing the distribution shape of the slope ratio (dR1 _{/ 2} ) of the sample lens 1 and the sample lens 3, the formability prediction, and the actual molding result of the R1 surface.
8 is a graph showing an example of the shape of d'R _{1/2 obtained} by again differentiating the equation of the slope ratio (dR _1/2 ).
9 is a graph showing an example of the shape of another d R _1/2 .
10 is a graph showing the distribution shape of d _1/2 , the formability prediction, and the actual shape of the sample lens 4, the sample lens 5, and the sample lens 6 by differentiating the slope ratio (dR _1/2 ) 1 is a comparative diagram showing the result of molding the R1 surface.
Fig. 11 is a comparative diagram showing a specific embodiment of a biconvex MO lens on both sides of an aspheric surface. Fig.
FIG. 12 is a comparative diagram showing a specific embodiment of a double concave MO lens on both sides of an aspherical surface.
FIG. 13 is a comparative diagram showing a specific embodiment of a convex meniscus MO lens on both sides of an aspherical surface.
Fig. 14 is a comparative diagram showing a specific embodiment of a concave meniscus MO lens on both sides of an aspherical surface. Fig.
Fig. 15 is a comparative diagram showing a specific embodiment relating to a biconvex MO lens on one side aspherical surface. Fig.
16 is a comparative diagram showing a specific embodiment of a double-concave MO lens on one-side aspherical surface.
17 is a comparative diagram showing a specific embodiment of a convex meniscus MO lens on one side aspherical surface.
18 is a comparative diagram showing a specific embodiment of a concave meniscus MO lens on one side aspherical surface.
19 is a flowchart showing an embodiment of a method of designing a lens system according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an image diagram when a glass spherical body G is pressed with upper and lower molds M1 and M2 and molded with a covar-attached positive convex lens; When strain stress is applied to the glass spheres G with the molds M1 and M2, the glass moves in the lateral direction (radial direction). At this time, if the space between the molds M1 and M2 is open (cylindrical, prismatic) side, the stress is divergent, so that it is not a covar-attached positive convex lens (upper right in Fig. 1). On the other hand, if there is a cylindrical mold (W) on the space side between the molds (M1, M2), the deformation stress generated in the glass is the space of the mold (W) So that it becomes a cobalt-mounted biconvex lens (lower right of Fig. 1). The present embodiment proposes an index of a rotationally symmetric aspherical shape of an aspherical MO lens in which strain stress is confined as shown in the lower right of Fig.

The method for predicting the degree of molding difficulty of an aspherical MO lens according to the present embodiment is a method for predicting the degree of molding difficulty of an aspherical MO lens having a rotationally symmetric aspheric surface represented by the following equation 1 on at least one surface (at least one of R1 surface and R2 surface) .

[ Equation 1 ]

In Equation (1), R, K, a, b, c, d. Is a constant, and y and x are the radius and displacement of the lens, respectively.

If the value of x at an arbitrary point y _i is x _i , then Equation 1 is transformed into Equation 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) ''.

& Quot; (1) & quot ;

In this embodiment, it is premised that an aspheric surface of the aspherical MO lens to be formed is provided with input. The provision of data is performed for a client (mold maker) from the client (lens maker), and the data is sent to the lens design program / apparatus.

2A is a coordinate system showing the above-mentioned lens shape. Here, since the convex (meniscus) lens is formed by press molding, the convex surface is formed into a lower mold. For convenience, x and y are directly rewritten as shown in Fig.

From Fig. 2B, the slope distribution (dR) of the lens shape is given by the following equation (2) by differentiating the equation (1 ') once.

& 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''.

[ Equation 2 ]

& Quot; (2) & quot ;

FIG. 3 shows an example of plotting the tilt distribution dR ₁ and the tilt distribution dR ₂ with respect to y, that is, the radius of the convex meniscus lens.

In this embodiment, the slope ratio (dR1 _{/ 2} ) obtained by normalizing the slope of the R1 surface to the slope of the R2 surface is used in predicting the difficulty of forming the aspherical MO lens. That is, the slope ratio (dR1 _{/ 2} ) is defined by Equation (3) which is obtained by dividing Equation 2 'into Equation 2''.

& Quot; (3 ) & quot ;

In Equation (3), if y _i and? Are the same on the R 1 and R 2 surfaces, Equation (3) becomes Equation (4).

& Quot; (4 ) & quot ;

The slope ratio (dR1 _{/ 2} ) obtained in the equation (4) is a value obtained by normalizing the slope of the R1 surface with the slope of the R2 surface. Therefore, the slope ratio is an index of aggregation and divergence of deformation stress or holding stress . 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 Shape stability (ease of molding, difficulty in molding).

a) The slope ratio (dR _1/2 ) increases monotonically = The slope of the R1 surface relatively increases toward the outer direction = Aggregation of stress

→ R1 surface shape is stable trend

b) The slope ratio (dR _1/2 ) is monotonically reduced = The slope of the R1 surface is relatively small toward the outer direction =

→ R1 surface shape is unstable tendency

c) The slope ratio (dR1 _{/ 2} ) has an inflection point = an inflection point of stress coherence and divergence

→ R1 surface shape is unstable tendency

As described above, even if the same convex meniscus lens has an aspherical shape in which the inclination ratio dR _1/2 increases monotonously, it is expected that a stable lens shape is obtained, the lens shape becomes unstable when monotonous reduction and inflexion points are present. Fig. 4 is a list of the above relationships.

Fig. 5 shows an example of the cross-sectional shape of the convex meniscus lens of Sample 1 and Sample 2. Fig. 6 shows the distribution shape of the slope ratio (dR1 _{/ 2} ) of the sample 1 and the sample 2, , And an example of actual molding results. Sample 1 in which the slope ratio (dR1 _{/ 2} ) was monotonous increased the actual molding result of the R1 surface, whereas in the sample 2 having the inflection point at the slope ratio (dR1 _{/ 2} ) It was confirmed that the result was unstable and the quality was low. In Fig. 6 (and the following drawings), the molding results are obtained by molding a plurality of sample lenses in the same molding die and superimposing a graph in which the shape of the sample lenses is investigated. In the graph of the actual molding results, (Excellent lens shape quality), and a large deviation indicates that the molding stability is poor (lens shape quality is poor).

Next, Fig. 7 shows the relationship between the shape of the slope ratio (dR1 _{/ 2} ) and the shape of the slope ratio (dR1 _{/ 2} ) by substituting the sample 2 of Fig. 6 and the R2 surface of the sample 1, The shape of each slope ratio (dR1 _{/ 2} ), the formability prediction, and the actual results of the molding, with respect to the sample 3 in which the monotone increase is changed to the monotone increase. It has been confirmed that the moldability is improved by changing the shape of the R2 surface (changing the shape of the dR1 _{/ 2} ) even though the result of molding the R1 surface is a problem. That is, the R2 surface shape is closely related to the formability of the R1 surface.

As described above, the shape of the slope ratio (dR1 _{/ 2} ) obtained by dividing the rotationally symmetric aspherical equation of the R1 surface of the aspherical MO lens by one time and the ratio of the equation obtained by differentiating the rotationally symmetric aspherical equation of the R2 surface by one time It has been found out that moldability can be judged by examination. On the other hand, it has also been found that the distribution shape of the tilt ratio (dR1 _{/ 2} ) is complicated, and there is a case in which sufficient formability can not be judged only by the shape of the tilt ratio (dR1 _{/ 2} ). Fig. 8 shows an example of the shape of such a slope ratio dR1 _{/ 2} .

In this case, the gradient ratio (dR1 _{/ 2} ) of the above equation (4) is again differentiated (the equation ( ₁ ) is differentiated twice) to obtain d1R1 _{/ 2} of the following equation The moldability can be predicted.

& Quot; (5 ) & quot ;

Fig. 9 shows an example of the shape of d R _1/2 , which is interesting in the equation of the slope ratio (dR _1/2 ) in Fig. This d'R _1/2 has a definite inflection point, so that the molding stability is expected to be low, and when molded, it was as expected.

Fig. 10 shows an example of the shape of d'R _1/2 , the formability prediction, and the actual result of molding. Sample 5 (the same as Sample 1 in the previous example) in which d R _1/2 is monotonous increases the actual molding result on the R 1 side, whereas Sample 4 having the inflection point in dR _{1 /} ) And Sample 6, it was confirmed that the actual molding result of the R1 surface was unstable and the production yield was poor.

The above discussion of the aspherical convex meniscus MO lens has been confirmed to be based on both convex, concave, convex meniscus and concave meniscus. In addition, the present invention is applicable not only to both-face aspherical MO lenses but also to one-face aspherical MO lenses. Also, it does not matter what kind of press machine the center material, the center thickness, the lens diameter, the presence of the land, the presence of the coat, the material thereof, and the like.

Hereinafter, examples of the lens cross-section, the shape of the dR _1/2, the shape of the d R _1/2 , and the formability prediction with respect to the both-side aspherical surface and one-side aspherical surface MO lens including specific aspheric surfaces will be described. 11 to 18, "E ± a" means "× 10 ± ^a ".

Figs. 11, 12, 13, and 14 are specific examples of a biconvex lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens as double-sided aspheric MO lenses.

Fig. 11 shows aspherical surface data of three double-sided aspheric double-convex MO lenses. (R, k, a, b, c, and d) of the aspheric surface on the R2 surface are set to the same values, Is designed as shown in Fig.

Of Figure 11, the embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. In the middle of the figure, the middle example shows that there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first recognized in d'R _1/2 , Yes. In the same figure, in the right side example, it was predicted that the molding was difficult because the inflection point was confirmed in dR _1/2 , but the inflection point was confirmed by evaluating d R _1/2 .

Fig. 12 shows aspherical surface data of three double-sided aspheric double concave MO lenses. (R, k, a, b, c, and d) of the aspheric surface on the R2 surface are set to the same values, Is designed as shown in Fig.

In Fig. 12, the example on the left is an example in which dR1 _{/ 2} and dR1 _{/ 2} have no inflection point and are expected to be molded in the first and second differentiations. In the middle of the figure, in the example in the middle, there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first confirmed in d'R _1/2 , to be. In the same figure, in the right side example, it was predicted that the molding was difficult because the inflection point was confirmed in dR _1/2 , but the inflection point was confirmed by evaluating d R _1/2 .

Fig. 13 shows aspherical surface data of three double-sided aspheric convex meniscus MO lenses. (R, k, a, b, c, and d) of the aspheric surface on the R2 surface are set to the same values, Is designed as shown in Fig.

Of Figure 13, the embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. In the middle of the figure, in the example in the middle, there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first confirmed in d'R _1/2 , to be. In the same figure, in the right side example, it was predicted that the molding was difficult because the inflection point was confirmed in dR _1/2 , but the inflection point was confirmed by evaluating d R _1/2 .

Fig. 14 shows aspherical surface data of three double-sided aspheric concave meniscus MO lenses. (R, k, a, b, c, and d) of the aspheric surface on the R2 surface are set to the same values, Is designed as shown in Fig.

Of Figure 14, an embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. In the middle of the figure, in the example in the middle, there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first confirmed in d'R _1/2 , to be. In the same figure, in the right side example, it was predicted that the molding was difficult because the inflection point was confirmed in dR _1/2 , but the inflection point was confirmed by evaluating d R _1/2 .

Figs. 15, 16, 17, and 18 are specific examples of a biconvex lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens as one-side aspherical surface MO lenses.

Fig. 15 shows aspherical surface data of three single-sided aspheric double-convex MO lenses. (R2, k, a, b, c, and d) of the aspheric surface on the R1 surface are designed as shown in Fig.

In Fig. 15, the example on the left is an example in which neither dR1 _{/ 2} nor dR1 _{/ 2} has an inflection point, and it is predicted that the first and second differentiates are for molding. 15, the example in the middle of the figure shows that there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first recognized in d'R _1/2 , to be. In Fig. 15, in the right embodiment, it was predicted that the molding was difficult because the inflection point was confirmed in dR1 _{/ 2} , And the inflection point was confirmed.

16 shows aspherical surface data of three single-sided aspheric double concave MO lenses. (R2, k, a, b, c, and d) of the aspheric surface on the R1 surface are designed as shown in Fig. 16, while the R2 surface is formed of a spherical surface having a constant curvature.

Of Figure 16, an embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. In the middle example in Fig. 16, in the example in the middle, there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first confirmed in d'R _1/2 , to be. 16, in the right embodiment, it was predicted that the molding was difficult due to the fact that the inflection point was confirmed in dR1 _{/ 2} , but the inflection point was also confirmed by evaluating d1R1 _{/ 2} .

Fig. 17 shows aspherical surface data of three single-surface aspherical convex meniscus MO lenses. (R2, k, a, b, c, and d) of the aspherical surface in the R1 surface are designed as shown in Fig. 17, while the R2 surface is formed of a spherical surface having a constant curvature.

Of Figure 17, an embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. 17, the example in the middle of the figure shows that there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first recognized in d R _1/2 , to be. 17, it is predicted that the molding is difficult due to the fact that the inflection point in dR1 _{/ 2} is confirmed, but the inflection point is confirmed by evaluating d1R1 _{/ 2} .

Fig. 18 shows aspherical surface data of three one-face aspherical concave meniscus MO lenses. (R2, k, a, b, c, and d) of the aspheric surface on the R1 surface are designed as shown in Fig. 18, while the R2 surface is formed of a spherical surface having a constant curvature.

Of Figure 18, an embodiment of the left side dR _1/2, R _1/2 d'both inflection points are not, the exemplary predicted as for example forming in the first derivative, second derivative. 18, the middle example shows that there is no inflection point in dR _1/2 , it is predicted to be for molding, the inflection point is first recognized in d R _1/2 , to be. 18, in the right embodiment, it was predicted that the molding was difficult due to the fact that the inflection point was confirmed in dR1 _{/ 2} , but the inflection point was confirmed by evaluating d1R1 _{/ 2} .

In the embodiment shown in Figs. 11 to 18, both of dR1 _{/ 2} and dR1 _{/ 2} are set as a single judgment criterion "whether there is an inflection point". From these examples, it is possible to predetermine the formability only by determining whether or not an inflection point exists in dR1 _/ 2. However, by using whether or not there is an inflection point in dR1 _{/ 2} , . Particularly, it was confirmed that whether or not the inflection point of the second differential equation is universal has a good formability and poorness regardless of the lens shape. If the presence or absence of the inflection point is not clear in the equation of the second differential, the presence or absence of the inflection point may be examined in the form of three or more differentiations.

According to the method of predicting the degree of molding difficulty according to the present embodiment, it is possible to propose, based on the prediction result (prediction result that molding is difficult), a request for change of the aspherical shape from the manufacturing site to the design section In addition to this, the quality assurance department can contribute to the review of the method of selecting the molded lens and the pre-ordering of the lens, and the sales department can contribute to the negotiation by considering the low manufacturing yield and screening cost. As a result, it is possible to produce a product with high production yield, delivery at an appropriate price, and no delay or delay in delivery.

It is also possible to adopt a method of predicting the degree of molding difficulty according to the present invention in a lens design program. In general, in a lens design performed by an automatic designing program, before starting automatic designing, the designer inputs the focal length, the number of lenses, the allowable aberrations, the introduction possibility of aspherical surfaces, As a result of the automatic design, the slope ratio (dR _1/2 ) and the slope ratio (d R _1/2 ) of the generated aspherical MO lens are calculated using the aspherical surface data of the front and back surfaces, If predicted and displayed, a warning can be issued to the designer that moldability is difficult, and the designer can change the design based on the warning. Alternatively, in order to prevent an undesirable slope ratio (dR _1/2 ) and a slope ratio (d'R _1/2 ) from occurring in an automatic design program (a desirable slope ratio (dR _1/2 ) and a slope ratio _1/2 )) may be included in the subroutine.

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

First, in the course of designing the lens system, lens data including rotationally symmetric aspherical surface data of R1 surface and R2 surface are input (step S11).

Subsequently, the input aspherical surface data of the R1 surface and the R2 surface are differentiated once, and the slopes of the R1 surface and the R2 surface are respectively calculated, and either the slope of the R1 surface or the slope of the R2 surface is divided into the other, The equation dR _1/2 is obtained (step S12).

Subsequently, the equation dR _1/2 of the slope ratio obtained in step S12 is again differentiated once to obtain the slope formula d'R _1/2 (step S13).

The equation dR _1/2 of the slope ratio obtained in step S12 and the slope formula d'R _1/2 (Step S14: NO, step S15: NO), it is determined that the molding difficulty of the aspherical lens is low (easy molding) (step S16).

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

When there is a design solution in the redesigned aspherical surface data in step S18 (step S19: YES), the already inputted aspherical surface data is replaced with the redesigned aspherical surface data, and the processing in steps S12 to S19 is repeated . That is, when aspheric surface data having no inflection point in the tilt ratio (dR1 _{/ 2} ) and the tilt ratio (d1 _{/ 2} ) are obtained as long as the design solution exists in the redesigned aspherical surface data (Step S14: NO, step S15: NO), the lens design of the lens system including the aspheric lens with low molding difficulty (easy to mold) is repeated.

When step S18 has not to design in the aspherical surface data in the re-design (designed to not have the inflection point to the slope ratio (dR _1/2) and the inclination ratio (R _d'1/2) does not exist) (step S19: NO ), The manufacture of a null lens, the adoption of a multi-step press, the application of a side connection sleeve in a press type, or the correction polishing of a molded lens (step S20).

Although the slope ratio (dR1 _{/ 2} ) obtained by dividing the slope of the R1 surface by the slope of the R2 surface is used in the above embodiments, the same determination can be made by using the slope ratio obtained by dividing the slope of the R2 surface by the slope of the R1 surface have. In the embodiments shown in Figs. 11 to 14, the values of the R1 plane are unified with respect to the three embodiments and the values of the R2 plane are changed. However, the present invention is not limited to this. Although the above embodiment shows an example in which dR _1/2 is increased and is for molding, it is not limited to this, but the present invention can also be applied to a case where it is reduced.

In the above-described embodiment, the rotationally symmetric aspherical surface data is provided to the mold maker from the lens maker, but the design maker of the camera maker may be provided with respect to the manufacturing department. Incidentally, the case where the aspheric data moves within the lens design program / apparatus is also included in the provision of data.

In addition, the glass material used for molding the glass lens described in the above-mentioned embodiments is obtained by combining the glass raw materials at a predetermined ratio, obtaining the melting, homogenizing, and refining steps, supplying the molten glass to the mold, The molten glass supplied onto the mold was molded into a predetermined shape (spherical preform or flat gob, approximate shape preform approximated to the shape of the aspherical lens to be obtained) to obtain a glass material.

Then, the glass material was subjected to precision press molding by a press molding die having a molding surface subjected to precision machining, and the surface shape of the molding surface was transferred to a molding material to manufacture a lens. At this time, the glass material is heated to a temperature at which it exhibits a viscosity of about 10 ⁶ to 10 ¹² dPa · s, subjected to precision press molding, cooled to a temperature of 10 ¹² dPa · s or higher, and then the precision press- .

Claims (10)

As a method for predicting the degree of molding difficulty of an aspheric glass mold lens in which at least one of the R1 surface and the R2 surface is a rotationally symmetric aspherical surface represented by the following aspherical surface expression (1)
Inputting lens data including the rotationally symmetric aspherical surface data of R1 surface and R2 surface;
Calculating the slopes of the R1 surface and R2 surface by differentiating the aspherical surface expression (1) of R1 surface and R2 surface by 1 time;
And a step of dividing one of the inclination of the R1 surface and the inclination of the R2 surface into the other and obtaining an expression of a slope ratio which is an index of the degree of molding difficulty.
[Equation 1]

2. The method according to claim 1, wherein whether or not an inflection point is included in the formula of the inclination ratios of the R1 surface and the R2 surface is taken as an index of the degree of molding difficulty, and when there is an inflection point, A method for predicting forming difficulty of an aspherical glass mold lens. The method according to claim 1, further comprising differentiating the formula of the tilt ratio of the R1 surface and the R2 surface by one or more times, and using the notion as an index of molding difficulty. 4. The method according to claim 3, wherein whether or not an inflection point is included in an expression for differentiating the formula of the inclination ratio of the R1 side and the R2 side by more than one time is used as an index of the degree of molding difficulty, Wherein the method for predicting the degree of molding difficulty is as follows. A method of designing a lens system including an aspheric glass mold lens having at least one of an R1 surface and an R2 surface as a rotationally symmetric aspherical surface expressed by the following aspherical surface expression (1)
Inputting lens data including the rotationally symmetric aspherical surface data on the R1 surface and the R2 surface during the designing;
Calculating the slopes of the R1 surface and R2 surface by differentiating the aspherical surface expression (1) of R1 surface and R2 surface by 1 time;
Dividing one of a slope of the R1 surface and a slope of the R2 surface into the other and obtaining an expression of the slope ratio;
And designing the expression of the inclination ratio as an index of the degree of molding difficulty of the aspherical glass mold lens.

6. The method according to claim 5, wherein whether or not an inflection point is included in the formula of the inclination ratio of the R1 surface and the R2 surface is set as an index of the degree of molding difficulty, A method of designing a lens system including an aspherical glass mold lens. 6. The method according to claim 5, further comprising the step of differentiating the formula of the inclination ratio of the R1 surface and the R2 surface by one or more times, determining whether the molding is difficult or not, And the aspherical surface-shaped glass mold lens for predicting that the lens is for molding. The method of designing a lens system according to any one of claims 5 to 7, further comprising a step of warning when it is determined that molding is difficult in the step of determining the degree of molding difficulty. The method according to any one of claims 5 to 7, wherein, in the step of determining the degree of plasticity, an inflection point is included in an expression of differentiating the expression of the inclination ratio of the R1 side and the R2 side or the expression of the inclination ratio one more time The aspherical surface data is redesigned and the gradient of the R1 and R2 surfaces or the expression of the gradient of the gradient is again differentiated one or more times as long as there is a redesign solution, Lt; RTI ID = 0.0 > a < / RTI > aspheric lens mold lens. The method according to claim 9, further comprising the steps of: preparing a null lens, employing a multi-step press, applying a side connection sleeve to a press mold, A method for designing a lens system including an aspherical glass mold lens that determines the adoption of the above method.

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