TWI579597B - Method for predicating difficulty in formation of aspherical glass molded lens and method for designing lens system containing aspherical glass molded lens - Google Patents

Description

Method for predicting forming difficulty of aspherical glass molded lens and lens system design method for aspherical glass molded lens

The present invention relates to a method of predicting the ease of forming a molded aspherical glass lens and a lens system design method comprising the aspherical glass molded lens.

Conventionally, the moldability of a glass molded lens (hereinafter referred to as an MO lens) has been determined based on an empirical method such as a glass material, a center thickness, a lens diameter, a presence or absence of a land, and a meniscus. For example, in the case of a positive meniscus lens having the same glass material and the same center thickness, a smaller surface diameter can provide a good surface shape.

Prior art literature

Patent Document 1: Japanese Patent Publication No. Sho 61-32263

However, the actual situation is that at the press forming site, an aspherical MO lens which is inferior to the empirical rule and has a very poor yield is frequently generated. The manufacturing process of the aspherical MO lens is a relationship as follows: the orderer (for example, a camera (lens) manufacturer) submits the shape specification of the aspherical lens whose shape is determined according to the lens design to the orderer (such as a mold manufacturer) ( n (glass material), r (curvature radius), d (thickness), and data including a rotationally symmetric aspherical shape, nrd-aspherical data), and the order acceptor forms an aspherical surface MO that is faithful to the shape of the shape specification. lens. The same is true when the order acceptor is a division of the camera manufacturer. In this relationship, even if the aspherical MO lens that is ordered is inferior in formability and the yield is poor, various types of press equipment are used to form the orderer side of the molded lens. It is also completely (or almost) impossible to cope. That is to say, the actual situation is that even if the shape is difficult (the yield is poor), the order acceptor cannot propose to the orderer to change the aspherical shape, and there is no basis for the change request. Moreover, a lens system including an aspherical MO lens which is difficult to form results in that it is difficult to obtain stable high optical performance. The inventors of the present invention believe that the biggest problem is that there is no clue in the past to know what the amorphous MO lens formability is caused by, and only the empirical method is used for judgment.

SUMMARY OF THE INVENTION An object of the present invention is to obtain a prediction method for forming difficulty, which is used for predicting the forming difficulty of an aspherical MO lens which has no clue in the past, and is a clue for changing the design shape of the aspherical MO lens itself. Further, an object of the present invention is to obtain a design method (program) according to which a design of a lens system including an aspherical lens can be used as a design result of an aspherical MO lens including forming difficulties. Warning of the difficulty of forming, the design itself changes.

On the basis of the following assumptions, the inventors of the present invention have attempted to predict the forming difficulty of the surface shape based on the index of the rotationally symmetric aspherical shape, that is, the aspherical formula, and the present invention has been completed. The deformation stress on the glass is affected by the shape of the surface, and the deformation stress can be divided into concentration and dispersion. If the deformation stress is concentrated, the molding is easy. On the other hand, if the deformation stress is dispersed, the molding is difficult. Therefore, if the deformation stress can be predicted, Concentration/dispersion can predict the difficulty of forming an aspherical shape.

The present invention provides a method for predicting the difficulty of forming an aspherical glass molded lens for predicting at least one of the R1 surface and the R2 surface as follows The forming difficulty of the rotationally symmetric aspherical aspherical glass molded lens represented by the aspherical formula (1), and the method for predicting the forming difficulty of the aspherical glass molded lens includes: inputting the above-mentioned R1 surface and R2 surface a step of rotating the lens data of the symmetric aspherical material; performing a step of differentiating the aspherical formula (1) of the R1 plane and the R2 plane to calculate the slopes of the R1 plane and the R2 plane, respectively; and using the slope of the R1 plane One of the slopes of the R2 plane and the slope of the R2 plane are divided by the other, thereby obtaining a step of a slope ratio formula as an index of forming difficulty.

In the method for predicting the difficulty of forming aspherical glass molded lens of the present invention, the slope ratio formula of the R1 plane and the R2 plane can be further differentiated one time or more, and the differential formula is used as an index of forming difficulty.

More specifically, whether the slope ratio of the R1 plane and the R2 plane or the formula for further determining the slope ratio further includes an inflection point as an index of forming difficulty, and may have an inflection point. In the case, it is predicted that the forming is difficult, and in the case where there is no inflection point, it is predicted that the forming is easy.

The present invention also provides a method of designing a lens system including an aspherical glass molded lens that uses at least one of the R1 plane and the R2 plane as a rotation represented by the following aspherical formula (1) a symmetrical aspherical surface, wherein the design method of the lens system including the aspherical glass molded lens includes: step of inputting lens data of the rotationally symmetric aspherical material including the R1 surface and the R2 surface during the design process; The aspherical formula (1) of the R1 plane and the R2 plane is subjected to a first differentiation to calculate the slopes of the R1 plane and the R2 plane, respectively; using the slope of the R1 plane and the R2 plane The step of dividing one of the slopes by the other to obtain a formula of the slope ratio thereof; and the step of using the slope ratio as the index of forming difficulty of the aspherical glass molded lens.

In the design method of the lens system including the aspherical glass molded lens of the present invention, the slope ratio formula of the R1 plane and the R2 plane can be further differentiated one time or more, and the differential formula is used as an index of forming difficulty.

In the step of determining the ease of formation, whether the slope ratio of the R1 plane and the R2 plane or the formula for the slope ratio is further differentiated one or more times includes an inflection point as an index of forming difficulty, and may have an inflection point. In the case of the case, it is predicted that the forming is difficult, and in the case where there is no inflection point, it is predicted that the forming is easy.

In the step of determining the ease of formation, the step of issuing a warning if it is determined that the forming is difficult may be further included.

According to the design method of the lens system including the aspherical glass molded lens of the present invention, in the step of determining the ease of formation, the slope ratio on the R1 plane and the R2 plane, or the formula of the slope ratio is further differentiated one time or more When the inflection point is included in the formula, the aspherical data is redesigned, and the design is continued as long as there is a redesigned solution until the slope ratio of the R1 plane and the R2 plane, or the formula of the slope ratio is further differentiated one time or more. There is no inflection point in the formula.

Moreover, even if there is no redesigned solution even if the aspherical material is redesigned, it is decided to use a manufacturing null lens, a multistage press, and a side abutting sleeve for the stamping die. Any one or more of the cylinder and the corrected abrasive forming lens law.

According to the present invention, the forming difficulty of the aspherical MO lens can be predicted based on the lens data including the rotationally symmetric aspherical formula. Therefore, by feeding back the prediction of the forming difficulty to the lens design department to promote the change in the aspherical shape, it is possible to replace the aspherical MO lens which is easy to form. In addition, in the step of lens design, warning of the difficulty of forming the aspherical MO lens, or continuing to redesign as long as there is a redesigned solution in the aspheric formula, it can be done without waiting for feedback from the forming site (including The design of a lens system for forming an aspherical MO lens which is easy to form, as a result, a lens system having stable high optical performance can be obtained at a low price.

Fig. 1 is a view showing a state in which a glass lens G is pressed by upper and lower molding dies M1 and M2 to form a lenticular lens with an edge. If a deformation stress is applied to the glass sphere G using the forming molds M1, M2, the glass moves in the lateral direction (radial direction). At this time, if the side (cylindrical, angular cylindrical) side portion between the molding dies M1 and M2 is opened, the stress is dispersed and it is not formed into a belt-edge lenticular lens (upper right in FIG. 1). On the contrary, if the space side portion between the forming dies M1, M2 has a cylindrical trunk mold W, the deformation stress generated on the glass is enclosed in the space between the trunk model W and the forming dies M1, M2. Inside, it is shaped into a lenticular lens with an edge (bottom right of Figure 1). The present embodiment proposes an index for the rotationally symmetric aspherical shape of the aspherical MO lens whose deformation stress is closed as shown in the lower right side of FIG.

Prediction of forming difficulty of aspherical MO lens based on the present embodiment The premise of the method is that the rotationally symmetric aspherical surface represented by the following formula (1) is provided on at least one side (at least one of the R1 plane and the R2 plane) of the positive and negative of the MO lens as the object.

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

Further, if the value of x on any point y _i is set to x _i , the formula (1) is deformed to the following formula (1').

Further, if a different point having a minute δ with respect to y _i is set as y _{i +} δ, the formula (1') becomes the following formula (1").

In the present embodiment, it is assumed that the aspherical surface data of the aspherical MO lens which is a molded article is received and input. The information is provided by the orderer (lens manufacturer) to the orderer (mold manufacturer) and the data is sent to the lens design program/device.

Fig. 2A is a coordinate system showing the above lens shape. Here, since the press forming of the convex (meniscus) lens is formed into a convex surface using the lower mold, x, y is directly rewritten from Fig. 2A to that shown in Fig. 2B for convenience.

According to FIG. 2B, the slope distribution dR of the lens shape is given by the following formula (2) by slightly dividing the formula (1").

Thus, the slope of the slope of the R1 surface (first surface, the incident surface) and R2 dR ₁ distribution surface (the second surface, reflective surface) dR ₂ distribution is represented by the following formula (2 ') and the equation (2').

FIG. 3 shows an example in which these slope distributions dR ₁ and dR ₂ are plotted against the radius of y, that is, the convex meniscus lens.

In order to predict the difficulty in forming the aspherical MO lens, the present embodiment adopts a slope ratio dR _{1/2 obtained} by normalizing the slope of the R1 plane by the slope of the R2 plane. That is, the slope ratio dR _1/2 is defined by the formula (3) obtained by dividing the formula (2') by (2").

In the formula (3), if y _i and δ are the same values used in the R1 plane and the R2 plane, the formula (3) becomes the formula (4).

From this, it is understood that the slope ratio dR _1/2 obtained by the formula (4) is a value obtained by normalizing the slope of the R1 plane by the slope of the R2 plane, so that it is possible to concentrate the deformation stress and the holding stress generated during press forming. / Decentralized indicators. That is, with respect to y _i , the slope of the different point y _i+ δ having a small δ in the outer diameter direction has the following relationship between dR _1/2 and the deformation stress or the holding stress, and it can be predicted that the result is that the R1 surface The shape stability (forming ease, forming difficulty) has an influence.

a) Slope ratio dR _1/2 monotonically increases = slope of R1 surface increases in the outer circumferential direction = concentration of stress

→R1 surface shape is stable trend

b) Slope ratio dR _1/2 monotonically decreasing = slope of R1 plane decreases in the outer circumferential direction = dispersion of stress

→R1 surface shape is unstable trend

c) slope ratio dR _1/2 has an inflection point = inflection point with stress concentration/distribution

→R1 surface shape is unstable trend

In this way, it can be predicted that even if the same convex meniscus lens is an aspherical shape whose slope is monotonously increased by dR _1/2 , a stable lens shape can be obtained, and in the case of monotonously decreasing and having an inflection point, The shape of the lens is unstable. Fig. 4 is a list showing the above relationship.

Fig. 5 shows an example of the sectional shape of the convex meniscus lens of Samples 1 and 2, and Fig. 6 shows the distribution shape, the shapeability prediction, and the actual forming result of the slope ratio dR _1/2 of the sample 1 and the sample 2. An example of this. It can be confirmed that in the sample 1 in which the slope ratio dR _1/2 monotonically increases, the actual forming result of the R1 plane is good, and conversely, in the sample 2 having the inflection point in the slope ratio dR _1/2 , the actual forming result of the R1 plane is obtained. Unstable and low quality. In Fig. 6 (and the same drawing below), a result of overwriting the forming result is a graph in which a plurality of sample lenses are formed using the same molding die and the shape is examined, and the actual forming result is shown. In the graph, if the deviation is small, the forming stability is good (the lens shape quality is high), and when the deviation is large, the forming stability is poor (the lens shape quality is poor).

Then, Fig. 7 shows an example of the shape of the respective slope ratio dR _1/2 , the shapeability prediction, and the actual forming result for the sample 2 and the sample 3 of Fig. 6, wherein the sample 3 is as follows Sample described: In the sample 2, the shape of the R1 face was not changed, but the shape of the R2 face was replaced with the shape of the R2 face of the sample 1, so that the shape of the slope ratio dR _1/2 was changed to monotonously increase. Although the problem is the result of the formation of the R1 surface, it can be confirmed that the shape of the R1 surface is improved by changing the shape of the R2 surface (changing the shape of dR _1/2 ). That is to say, the shape of the R2 surface is closely related to the formability of the R1 surface.

As described above, it can be clearly understood that if the formula for first-differentiating the rotationally symmetric aspherical formula of the R1 plane of the aspherical MO lens and the formula for the differential differentiation of the rotationally symmetric aspherical formula of the R2 plane are discussed, The shape of the slope ratio dR _1/2 can be judged. On the other hand, it is also clear that the distribution shape of the slope ratio dR _1/2 is complicated, and there is a case where sufficient shapeability determination cannot be performed only by the shape of the slope ratio dR _1/2 . Fig. 8 shows an example of the shape of such a slope ratio dR _1/2 .

In such a case, the slope ratio dR _1/2 of the above formula (4) (secondary differentiation of the formula (1") can be further differentiated to obtain d'R _{1/2 of the} following formula (5). And predict the formability by judging its shape.

Fig. 9 shows an example of the shape of d'R _1/2 obtained by re-differentiating the slope ratio dR _1/2 formula of Fig. 8 . It can be predicted that the d'R _1/2 has a clear inflection point and the forming stability is low, and if the actual forming is attempted, it is consistent with the predicted condition.

Fig. 10 shows an example of the shape of d'R _1/2 , the predictability of formability, and the actual forming result. It can be determined that d'R _1/2 monotonically increases sample 5 (same as previous sample 1), the actual forming result of the R1 surface is good, and conversely, the sample 4 with the inflection point in dR _1/2 (with the previous sample) In the same 2) and in the sample 6, the actual forming result of the R1 surface was unstable and the yield was poor.

It can be determined that the above aspherical convex meniscus MO lens is discussed as an example, whether it is a double convex, a double concave, a convex meniscus or a concave meniscus. In addition, not only a double-sided aspherical MO lens but also a single-sided aspherical MO lens is also established. Further, it is irrelevant to the glass material, the center thickness, the lens diameter, the presence or absence of a land, the presence or absence of a coating, the material thereof, and the type of the press.

Hereinafter, the double-sided aspherical surface and the single-sided aspherical MO lens including the specific aspherical shape formula are subjected to an example of the lens cross section, the shape of dR _1/2 , the shape of d'R _1/2 , and the shape prediction. Description. In Fig. 11 to Fig. 18, "E±a" indicates "x10± ^a ".

11, 12, 13, and 14 show a double-sided aspherical MO lens, which is a specific embodiment of a lenticular lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens.

In Fig. 11, aspherical data of three double-sided aspherical biconvex MO lenses is described. The respective parameters (R, k, a, b, c, d) of the aspherical surface in the R1 plane are set to the same value, and the parameters of the aspheric surface in the R2 plane are designed as shown in FIG. 11 (R, k). , a, b, c, d).

In Fig. 11, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in the figure, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed and predicted in d'R _1/2 It is difficult to form. Further, in the figure, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In Fig. 12, there are described three non-spherical biconcave MO lenses. Spherical data. Each parameter (R, k, a, b, c, d) of the aspheric surface in the R1 plane is set to the same value, and each parameter of the aspheric surface in the R2 plane (R, k, a, b, c, d) ) is designed as shown in FIG.

In Fig. 12, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in the figure, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed in d'R _1/2 and is predicted as Forming is difficult. Further, in the figure, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

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

In Fig. 13, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in the figure, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed in d'R _1/2 and predicted to be formed. difficult. Further, in the figure, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In Fig. 14, aspherical data of three double-sided aspherical biconcave MO lenses is described. Each parameter (R, k, a, b, c, d) of the aspheric surface in the R1 plane is set to the same value, and each parameter of the aspheric surface in the R2 plane (R, k, a, b, c, d) are designed as shown in FIG.

In Fig. 14, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in the figure, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed and predicted in d'R _1/2 It is difficult to form. Further, in the figure, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

15, FIG. 16, FIG. 17, and FIG. 18 show a single-sided aspherical MO lens, which is a specific embodiment of a lenticular lens, a biconcave lens, a convex meniscus lens, and a concave meniscus lens.

In Fig. 15, aspherical data of three single-sided aspherical biconvex MO lenses are described. While the R2 surface is formed as a spherical surface having a certain curvature, the respective parameters (R, k, a, b, c, d) of the aspheric surface in the R1 plane are designed as shown in FIG.

In Fig. 15, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in Fig. 15, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and is predicted to be easy to form, and an inflection point is first confirmed and predicted in d'R _1/2 It is difficult to form. Further, in Fig. 15, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In Fig. 16, aspherical data of three single-sided aspherical biconcave MO lenses are described. While the R2 surface is formed into a spherical surface having a certain curvature, R1 The various parameters (R, k, a, b, c, d) of the aspheric surface in the face are designed as shown in FIG.

In Fig. 16, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in Fig. 16, the middle embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed and predicted in d'R _1/2 It is difficult to form. Further, in Fig. 16, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In Fig. 17, aspherical data of three single-sided aspherical convex meniscus MO lenses are described. While the R2 surface is formed as a spherical surface having a certain curvature, the respective parameters (R, k, a, b, c, d) of the aspheric surface in the R1 plane are designed as shown in FIG.

In Fig. 17, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in Fig. 17, the middle intermediate embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed and predicted in d'R _1/2 It is difficult to form. Further, in Fig. 17, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In Fig. 18, aspherical data of three single-sided aspherical concave meniscus MO lenses are described. While the R2 surface is formed into a spherical surface having a certain curvature, the respective parameters (R, k, a, b, c, d) of the aspheric surface in the R1 plane are designed as shown in FIG.

In Fig. 18, the embodiment on the left side is an embodiment as follows: dR _1/2 and d'R _1/2 have no inflection points, and are predicted to be easily formed in one-time differential and second-order differential. Further, in Fig. 18, the middle intermediate embodiment is an embodiment as follows: there is no inflection point in dR _1/2 and it is predicted to be easy to form, and an inflection point is initially confirmed and predicted in d'R _1/2 It is difficult to form. Further, in Fig. 18, the embodiment on the right side is an embodiment as follows: an inflection point is confirmed in dR _1/2 , so that it is predicted to be difficult to form, but d'R _1/2 is also evaluated and confirmed. Inflection point.

In the embodiment of Figs. 11 to 18, both dR _1/2 and d'R _1/2 use "with or without inflection point" as the sole criterion for judgment. According to these embodiments, although the initial judgment of the formability can be performed only based on the presence or absence of the inflection point in dR1/2, it is possible to perform more accurate formability prediction by adding the inflection point in d'R1/2 as the judgment material. . In particular, it has been determined that the presence or absence of an inflection point of the formula of the second derivative has the universality of judging the formability regardless of the shape of the lens. Further, in the case where there is an inflection point in the formula in which the second derivative is not clear, it is also possible to investigate whether or not there is an inflection point in the differential equation of the third order or more.

According to the prediction method of the forming difficulty of the present embodiment, based on the prediction result (the prediction result of the forming difficulty), in addition to the requirement of changing the aspherical shape to the design department from the manufacturing site, it is also helpful to the quality assurance department. Studying the screening method of the formed lens and pre-arranging the zero lens, etc., in addition, also helps the business department to negotiate the selling price in view of low yield and screening cost. These results enable high-yield production, delivery at an appropriate price, no confusion, and delays in delivery.

In the lens design program, the prediction method of the forming difficulty of the present invention can be employed. Generally, when using the automatic design program for lens design, the designer inputs the focal distance, the number of lenses, the allowable aberration, the possibility of the introduction of the aspheric surface, the number of places, etc. before starting the automatic design. If, for the result of its automatic design, that is, the generated aspherical MO lens, the positive and negative aspherical data is used to calculate the slope ratios dR _1/2 and d'R _1/2 , and the difficulty of forming is predicted and displayed, then The designer can be warned that the formability is difficult, and the designer can change the design based on the warning. Alternatively, in the automatic design program, a subroutine for determining the aspherical shape may be included to avoid a poor slope ratio dR _1/2 and d'R _1/2 (to make it better). The slope ratio is a combination of dR _1/2 and d'R _1/2 ).

Fig. 19 is a flow chart showing an example of a lens designing method of the present invention.

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

Then, by first differentiating the aspherical data of the input R1 plane and the R2 plane, the slopes of the R1 plane and the R2 plane are respectively calculated, and one of the slope of the R1 plane and the slope of the R2 plane is divided by another. One party derives the formula dR _{1/2 of} its slope ratio (step S12).

Then, the slope obtained by the step S12 is further differentiated by the formula dR _1/2 to obtain the slope formula d'R _1/2 (step S13).

When there is no inflection point in the slope ratio formula dR _1/2 obtained in step S12 and the slope formula d'R _1/2 obtained in step S13 (step S14: NO, step S15: NO), it is judged to be aspherical. The forming difficulty of the lens is low (easy forming) (step S16), and the processing is terminated.

On the other hand, when there is an inflection point in both the slope ratio formula dR _1/2 obtained by the step S12 and the slope formula d'R _1/2 obtained by the step S13 (step S14: YES, step S15: YES), it is issued. The warning of the difficulty in forming the aspherical lens is high (step S17), and the aspherical material is redesigned (step S18).

When there is a design solution in the aspherical material redesigned by step 18 (step 19: YES), the aspherical data that has been input is replaced with the redesigned aspherical material, and steps S12 to are repeated. Processing of S19. That is, as long as there is a design solution in the redesigned aspherical material (step S19: YES), the lens design of the lens system including the aspherical lens having a low ease of formation is formed, until the slope ratio is obtained. Aspherical data without an inflection point in dR _1/2 and d'R _1/2 (step S14: No, step S15: No).

There is no design solution in the aspherical data redesigned by step S18 (there is no design solution having a slope ratio dR _1/2 and no inflection point in d'R _1/2 ) (step A19: No), Then, it is decided to adopt a method of manufacturing a zero lens, using a multi-stage press, applying a side abutting sleeve to the press die, and correcting one or more of the grinding-molded lenses (step S20), and then ending the process.

Further, in the above embodiment, although the slope of the surface R1 of R2 divided by the slope of the slope surface than dR _1/2, but the resulting slope even with a slope surface R2 divided by R1 slope surface ratio, The same judgment can be made. Further, in each of the embodiments in FIGS. 11 to 14, although an example in which the values of the R1 plane are kept consistent and the value of the R2 plane is changed in the three embodiments is shown, it is not limited thereto. Further, in the above embodiment, an example in which dR _{1/2 is} increased is shown and it is predicted that the forming is easy, but the present invention is not limited thereto, and the present invention can also be applied in the case of decreasing.

In the above embodiments, the provision of the rotationally symmetric aspherical material is performed by the lens manufacturer to the mold manufacturer, but there are cases where the design department of the camera manufacturer goes to the manufacturing department. In addition, the provision of data also includes the movement of aspherical data within the lens design program/device. Happening.

Further, the glass material for molding the glass lens described in the above embodiment is obtained by blending a glass raw material at a predetermined ratio, and performing a melting, homogenizing, and clarifying process to supply molten glass to a forming mold and performing the same. Cooling so that the molten glass supplied to the mold is shaped into a prescribed shape (preform and flat-shaped cough, and a shape approximate to the shape of the aspherical lens shape desired to be obtained) Thereby obtaining a glass material.

Then, the glass material is subjected to precision press forming using a press forming mold having a molding surface subjected to precision machining, and the surface shape of the molding surface is transferred onto the molding material to produce a lens. At this point, the glass material is heated to indicate 10 ⁶ ~ 10 ¹² dPa. The temperature of the viscosity around s and precision stamping, after cooling to indicate 10 ¹² dPa. After the temperature of the viscosity of s or more, the precision press-molded product is taken out from the press molding die.

G‧‧‧ glass sphere

M1‧‧‧Forming mold

M2‧‧‧forming mold

W‧‧‧Tropical mold

Fig. 1 is a schematic cross-sectional view showing a state in which a glass spheroid is pressed using a vertical molding die to form a flanged lenticular lens.

2(A) and 2(B) are graphs showing a coordinate system of a design state of a lens shape and a pressed state.

Fig. 3 is a graph showing an example of the inclination distribution of the incident surface (R1 surface) and the reflecting surface (R2) of the lens.

4 is a schematic view showing the distribution shape and formability of the inclination ratio dR _1/2 of the R1 surface and the R2 surface of the lens.

5(A) and (B) are cross-sectional views showing examples of lens shapes of the sample lens 1 and the sample lens 2.

Fig. 6 is a view showing a comparison of the distribution shape of the inclination ratio dR _1/2 of the sample lens 1 and the sample lens 2, the prediction of the formability, and the actual formation result of the R1 surface.

Fig. 7 is a view showing a comparison of the distribution shape of the inclination ratio dR _1/2 of the sample lens 1 and the sample lens 3, the prediction of the formability, and the actual formation result of the R1 surface.

Fig. 8 is a graph showing an example of the shape of d'R _1/2 which further differentiates the inclination ratio dR _1/2 formula.

Fig. 9 is a graph showing an example of the shape of other d'R _1/2 .

FIG d'R 10 represents a shape of the distribution system, forming prediction, and comparing the results of FIG R1 actual molding surface of the _half, the differential d'R _1/2 the sample lens 4, lens 5 and sample 6 sample lens The inclination of the R1 plane and the R2 plane is dR _1/2 .

Figure 11 is a comparison diagram showing a related embodiment of a double-sided aspherical biconvex MO lens.

Figure 12 is a comparison diagram showing a related embodiment of a double-sided aspherical biconcave MO lens.

Figure 13 is a comparison diagram showing a related embodiment of a convex meniscus MO lens having a double-sided aspherical surface.

Figure 14 is a comparison diagram showing a related embodiment of a double-sided aspherical concave meniscus MO lens.

Figure 15 is a comparison diagram showing a related embodiment of a single-sided aspherical biconvex MO lens.

Figure 16 is a comparison diagram showing a related embodiment of a single-sided aspherical biconcave MO lens.

Figure 17 is a comparison diagram showing a related embodiment of a convex meniscus MO lens of a single-sided aspherical surface.

Figure 18 is a comparison diagram showing a related embodiment of a concave meniscus MO lens of a single-sided aspherical surface.

Fig. 19 is a flow chart showing an embodiment of a design method of a lens system according to the present invention.

Claims (10)

A method for predicting the difficulty of forming an aspherical glass molded lens for predicting at least one of the R1 plane and the R2 plane as a rotationally symmetric aspherical aspherical glass represented by the following aspherical formula (1) A method of molding the difficulty of forming a lens, comprising: a step of inputting lens data of the rotationally symmetric aspherical material including an R1 plane and an R2 plane; and performing a differential differentiation of the aspherical formula (1) of the R1 plane and the R2 plane, Therefore, the steps of calculating the slopes of the R1 plane and the R2 plane, respectively, and dividing the slope of the R1 plane and the slope of the R2 plane by the other side, thereby obtaining the slope ratio formula as the index of forming difficulty , In the aspherical formula (1), R, K, a, b, c, d... are constants, and y and x are the radius and displacement of the lens, respectively. The method for predicting the forming difficulty of an aspherical glass molded lens according to claim 1, wherein the slope ratio of the R1 surface and the R2 surface is included in the formula as an index of forming difficulty, and there is an inflection point. In the case of the case, it is predicted that the forming is difficult, and in the case where there is no inflection point, it is predicted that the forming is easy. The method for predicting the forming difficulty of an aspherical glass molded lens according to claim 1, wherein the slope ratio formula of the R1 surface and the R2 surface is further differentiated one time or more, and the differential formula is used as forming difficulty. index. It is difficult to form aspherical glass molded lens as claimed in item 3 of the patent application. a degree prediction method in which an inflection point is included as an index of forming difficulty in a formula in which the slope ratio ratio of the R1 plane and the R2 plane is further subjected to one or more differentiation, and in the case of an inflection point, prediction is difficult to form. In the absence of an inflection point, it is predicted to be easy to form. A lens system design method for an aspherical glass molded lens, which is designed to include at least one of an R1 plane and an R2 plane as a rotationally symmetric aspherical surface represented by the following aspherical formula (1) A lens system design method for a glass molded lens, comprising: a step of inputting lens data of the rotationally symmetric aspherical material including R1 and R2 faces during a design process; and an aspherical formula for R1 and R2 faces (1) a step of performing a differential to calculate the slopes of the R1 plane and the R2 plane, respectively; and dividing the other of the slope of the R1 plane and the slope of the R2 plane by the other to obtain a formula of the slope ratio thereof; And a step of using the formula of the slope ratio as an index of forming difficulty of the aspherical glass molded lens, In the aspherical formula (1), R, K, a, b, c, d... are constants, and y and x are the radius and displacement of the lens, respectively. The method for designing a lens system comprising an aspherical glass molded lens according to claim 5, wherein whether the inflection point is included in the formula of the slope ratio of the R1 surface and the R2 surface is an index of forming difficulty, and there is an inflection point. In the case of the case, it is predicted that the forming is difficult, and in the case where there is no inflection point, it is predicted that the forming is easy. The method for designing a lens system including an aspherical glass molded lens according to claim 5, wherein the slope ratio formula of the R1 surface and the R2 surface is further differentiated one time or more, and the differential formula is used as a forming difficulty. In the case of an inflection point, the indicator is difficult to form, and in the absence of an inflection point, it is predicted to be easy to form. The method for designing a lens system comprising an aspherical glass molded lens according to any one of claims 5 to 7, further comprising the step of issuing a warning when it is judged that the forming is difficult in the step of determining the forming difficulty . A lens system design method comprising an aspherical glass molded lens according to any one of claims 5 to 7, wherein in the step of determining the forming difficulty, the slope ratio on the R1 plane and the R2 plane, or When the formula of the slope ratio further carries out the inflection point in the formula with more than one differential, the aspherical data is redesigned, and the design is continued as long as there is a redesigned solution until the slope ratio of the R1 plane and the R2 plane, or the slope ratio There is no inflection point in the formula for further differentiation of the above formula. For example, in the lens system design method of the aspherical glass molded lens of claim 9th, in the case where there is no redesigned solution even if the aspherical material is redesigned, it is decided to adopt a manufacturing zero lens and adopt a plurality of segments. Any one or more of the punching machine, the side abutting sleeve for the stamping die, and the corrected abrasive forming lens.