Matrix mold retainer, positioning method for matrix mold and method for winding tape on matrix mold

Abstract

To provide a matrix mold retainer, a positioning method for the matrix mold, and a method for winding a tape on the matrix mold, which can appropriately apply a prism to a progressive refractive power lens manufactured by appropriately adjusting the angle of a convex mold when forming the progressive refractive power lens which becomes internally progressive by means of molding.SOLUTION: This matrix mold retainer comprises: a body 2 in which an upper die 3 for forming the rear surface of a progressive refractive power lens and a lower die 5 for forming the front surface of the progressive refractive power lens are arranged; a guide 8 for holding the rear surface forming surface of the upper die 3 and the front surface forming surface of the lower die 5 in a state where they are arranged to face each other on the body 2; a projected reception plate 18 on which the edge or a part near the edge of the rear surface forming surface of the upper die 3 is supported and which is for holding the upper die 3 and the lower die 5 with an interval while they are arranged to face each other by the guide 8; and a lower die holding plate 19 on which the edge or a part near the edge of the front surface forming surface of the lower die 5 is supported.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mother mold holding device, a mother mold positioning method, and a mother mold tape wrapping method in lens manufacturing using a so-called cast finish method in which a liquid hardening type plastic material is filled into the cavity of a mother mold assembled with molds and hardened to form a plastic lens. [Background technology]

[0002] One conventional method for producing plastic lenses involves preparing a lens molding unit, filling its cavity (space) with a plastic material that is primarily of the thermosetting type, hardening it through a heat treatment using a specified heating history, and then removing the molded plastic lens. A lens molding unit is generally assembled by arranging a convex mold and a concave mold at a predetermined distance from each other and winding adhesive tape around the outer periphery of the mold to form a cavity inside. This state is called "mold assembly", and the state of the lens molding unit in which the mold assembly is completed and a cavity is formed inside is called a "mold". A filling tube is inserted into a part of the adhesive tape of this mold to fill it with a prepared plastic material (generally called a monomer). The lens molding unit filled with the plastic material is left in a heated atmosphere such as a heating furnace for several to several tens of hours to harden the plastic material and mold a plastic lens. Patent Document 1 shows an example of such a conventional manufacturing method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-244048 Summary of the Invention [Problem to be solved by the invention]

[0004] In the past, the production (manufacturing) of plastic lenses using cast finishing was limited to single-vision lenses, and progressive lenses, which require a wide variety of types, were not produced using cast finishing. The main reason for this is that progressive lenses require the preparation of convex molds for many different lens types according to the progressive surface shape, which is not cost-effective enough. However, if it is a progressive lens with general-purpose characteristics that can be used by many users with a certain added power, there is a sufficient demand for it without the need to prepare many different convex molds, so it is possible to produce progressive lenses using cast finishing in terms of cost-effectiveness. However, when manufacturing a progressive-addition lens by cast finishing, problems arise that are not present in the manufacture of a single-vision lens. When assembling the convex mold and the concave mold as described above, a mother mold holding device, generally called a "mold assembly holder", is used so that the centers of these molds coincide and are spaced apart before the adhesive tape is wound. The mother mold holding device temporarily fixes and holds the convex mold and the concave mold at a planned distance by arranging the convex mold and the concave mold facing each other at predetermined adjacent positions. In the case of convex molds and concave molds for single-focus lenses, the height of the entire circumference is uniform, so the distance between the convex mold and the concave mold can be always kept constant by placing the convex mold and the concave mold facing each other on the horizontal and parallel holding surfaces of the mother mold holding device.

[0005] However, for example, in a convex mold for forming the progressive surface of an internal progressive lens, the sag of the distance portion (upper side) is hollowed out relatively more than the near portion (lower side) due to the characteristics of the progressive lens, so the upper side is lower, and when this is set on the flat and parallel holding surface of a conventional master mold holding device, the upper part of the convex mold is placed on the holding surface with a large forward tilt. Therefore, if no measures are taken, the convex mold will be tilted forward relative to the concave mold, and the progressive lens produced will have more prism than necessary. In this case, excessive down prism will be added to the progressive lens. The present invention has been made in view of the problems existing in the conventional art, and aims to provide a master mold holding device, a master mold positioning method, and a master mold tape winding method that can appropriately provide prisms to a progressive power lens manufactured by appropriately adjusting the angle of a convex mold when forming an inner surface progressive lens by molding. [Means for solving the problem]

[0006] In order to solve the above problem, Means 1 provides a mother mold holding device for holding a mother mold used in plastic molding of an internally progressive meniscus lens-shaped progressive power lens, the mother mold holding device comprising: a main body in which a first mold for molding the back surface of the progressive power lens and a second mold for molding the front surface of the progressive power lens are disposed; positioning means for holding the back surface molding surface of the first mold and the front surface molding surface of the second mold in an opposing arrangement on the main body; a first holding section for supporting an edge or a portion close to the edge of the back surface molding surface of the first mold, for holding the first mold and the second mold opposed by the positioning means with a gap therebetween; and a second holding section for supporting an edge or a portion close to the edge of the front surface molding surface of the second mold, the first holding section being constituted by a plurality of protrusions.

[0007] This allows the edge or edge-proximal portion of the rear molding surface of the first mold for molding the rear surface (inner surface) of the progressive addition lens to be supported by the first holding section consisting of multiple protrusions, and by determining the amount of protrusion according to the position where the edge or edge-proximal portion of the rear surface of the progressive addition lens that the multiple protrusions face contact, the first mold can be held at a suitable angle that is not tilted forward too much. By not tilting the first mold forward too much, it is possible to prevent the progressive addition lens being molded from having more down prism than necessary. As described above, in the invention of Means 1, the angle of the first mold relative to the second mold is supported at "points" by multiple protrusions, so there is no need to form the entire first holding portion to match the complex shape of the rear molding surface of the first mold, which will become the rear surface of the progressive addition lens. Only the tip position of the protrusion, which will be the point of contact with the rear molding surface that is the supporting part, needs to be determined in relation to the first mold. The position of the tip of the protrusion should be based on the sag information of the rear molding surface of the first mold. Sag is the amount of sagging, which is the vertical displacement (unit is length, usually expressed in mm) from a reference surface (flat or spherical).

[0008] As one specific means, the coordinates of the sag of the rear molding surface of the first mold from the reference surface are obtained, and the protrusions are created so that the positions of the tips of the protrusions are determined based on the coordinates. For example, the simulation can be performed as follows. (1) First, sag data of the first mold is created, and a three-dimensional model is created based on this data. (2) Simulate the desired angle of the first mold relative to the second mold. By modifying the angle of the first mold, the sag data of the first mold will be displaced from the reference plane. (3) A position on the rear surface of the first mold where the tip of the protrusion is to be abutted is determined, and the coordinates of the displacement at that position are obtained. The protrusion is fabricated so that the tip of the protrusion is at that position.

[0009] The "main body" may be formed by opposing the first and second molds, and it is preferable that they be arranged at intervals in positions that form the front and back of a single member. The "positioning means" preferably surrounds a portion of the outer periphery of each of the first and second molds and can hold the first and second molds so that they face each other in the surface direction without lateral displacement. The "first holding portion" is composed of a plurality of protrusions, and it is preferable that the protrusions are arranged apart from one another so that the portions of the rear molding surface near the edges are spaced apart and held in a balanced manner. The "second holding part" is a surface that forms the surface (outer surface) of a progressive power lens, and since the surface of a progressive power lens is spherical or aspheric, the edge or the portion close to the edge of the surface forming surface of the second mold for forming that surface will be on the same plane. Therefore, it is preferable that the second holding part is configured as a horizontal surface.

[0010] In the second aspect, the plurality of protrusions are arranged in a plurality of spaced apart regions near the edge of the rear molding surface of the first mold. This allows the first mold to be supported by the protrusions without rattling. In the third aspect, the plurality of protrusions are arranged in two regions on the opposing edges or near the edges of the rear molding surface of the first mold. In this way, if there are a plurality of protrusions in the regions that are 180 degrees opposed to each other, the first mold becomes more stable. It is preferable that there are a plurality of protrusions in each of the two regions. In the fourth means, the two regions are provided along the vertical molding direction of the progressive power lens at the edge or a portion close to the edge of the rear molding surface of the first mold. When the two regions are located above and below the progressive power lens in this way, the protrusion will protrude more from the upper region, making it easier to see which is the upper side and less likely to cause a mistake in the up-down direction when attaching the first mold. In the fifth aspect, the protrusion is detachable from the main body. As a result, when manufacturing progressive power lenses with different progressive characteristics, it is sufficient to replace only the protrusions in accordance with the characteristics of the lenses, eliminating the need to prepare many master mold holding devices.

[0011] Means 6 is a method for arranging a master mold for plastic molding an internally progressive meniscus lens-shaped progressive power lens, in which a back molding surface of a first mold for molding the back surface of the progressive power lens and a front molding surface of a second mold for molding the front surface of the progressive power lens are arranged opposite each other, and when the opposed first and second molds are held with a gap between them, a portion near the edge of the back molding surface of the first mold is supported by a plurality of protrusions, and the arrangement angle of the first mold relative to the second mold is determined based on the coordinate value at the position where the protrusions abut against the first mold. This allows the first mold to be supported by a plurality of protrusions so that the first mold is held at a suitable angle without being tilted forward too much, and since only the tip positions of the plurality of protrusions need to be determined in relation to the first mold, it is not necessary to form the entire first holding part in accordance with the complex shape of the rear molding surface shape of the first mold, which is the rear surface of the progressive addition lens. Therefore, it is possible to easily change the arrangement angle of the first mold relative to the second mold. Furthermore, by changing the arrangement angle of the first mold, it is possible to prevent the progressive addition lens to be molded from having more down prism than necessary when plastic molding a progressive addition lens of an inner surface progressive type meniscus lens shape.

[0012] In the seventh aspect, the arrangement angle of the first mold with respect to the second mold is determined in terms of the amount of prism of the progressive dioptric power lens to be molded. Since it is necessary to ultimately make the prism amount of the manufactured progressive power lens a predetermined value as if it had been prism-thinned, it is appropriate to understand the relationship between the prism amount and the arrangement angle of the first mold and refer to the prism amount of the manufactured progressive power lens when verifying the angle, and it is also easy to judge whether the angle is appropriate. Since the prism amount for the arrangement angle of the first mold relative to the second mold is not uniform depending on the progressive characteristics, for example, when the shape of an actual first mold is designed, a progressive power lens using that first mold is prototyped, and the arrangement angle of the first mold is adjusted so that the prism amount gradually becomes appropriate. In addition, in means 8, data on the relative distance and posture of the first and second molds to be used as the master molds is acquired and stored using the positioning method for a master mold described in means 6 or 7, and the first mold and the second mold are caught by a catch means and temporarily separated from each other, and then the first mold and the second mold are placed opposite each other at a predetermined position based on the data, and in that state, adhesive tape is wrapped around the outer periphery of the first mold and the second mold to create the master mold. This makes it possible to plastically mold a progressive power lens of an inner surface progressive type meniscus lens shape in which the prism amount is a predetermined value. The inventions shown in the above means can be combined in any way. For example, at least a part of the configuration of at least one of the inventions from means 2 onwards may be added to all or a part of the configuration of the invention shown in means 1. In particular, it is preferable to add at least a part of the configuration of at least one of the inventions from means 2 onwards to the invention shown in means 1. In addition, any configuration may be extracted from the inventions shown in means 1 to means 8 and the extracted configurations may be combined. The applicant of the present application intends to obtain rights to inventions including these configurations. Effect of the Invention

[0013] In the inventions of each of the above claims, by supporting the first mold with a plurality of protrusions, the first mold can be held at a suitable angle relative to the supporting second mold so as not to tilt the first mold too far forward, and when supporting the first mold with a plurality of protrusions, only the tip positions need to be determined in relation to the first mold, so there is no need to form the entire first holding portion to match the complex shape of the rear molding surface of the first mold, which will become the rear surface of the progressive addition lens. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2A is a plan view of a master mold holding device according to an embodiment of the present invention, and FIG. 2B is a rear view of the same master mold holding device. [Diagram 2] Cross-sectional view taken along line AA in Figure 1. [Diagram 3] 1A is a plan view of an upper mold holding plate according to the same embodiment, and FIG. [Figure 4] FIG. 13 is an explanatory diagram illustrating a state immediately before an upper mold and a lower mold are attached to the same mother mold holding device. [Diagram 5] Schematic diagram (a) shows the upper mold placed at a predetermined position on the same master mold holding device, and (b) shows the lower mold placed at a predetermined position on the same master mold holding device. [Figure 6] FIG. 13 is an explanatory diagram showing the positions and angles of the protrusions supporting the upper mold when the upper mold is placed on the same master mold holding device. [Figure 7A] FIG. 13 is an explanatory diagram illustrating a state in which the ram of the mold suction device is approaching the upper and lower molds temporarily fixed to the mother mold holding device. [Figure 7B] 7B is an explanatory diagram illustrating a state in which the mold suction device has come closest to the state in FIG. 7A and has suctioned the upper mold and the lower mold. FIG. [Figure 7C] 13 is an explanatory diagram illustrating a state in which the ram of the mold suction device that has suctioned the upper and lower molds has retreated and the mother mold holding device has retreated from the movement line of the mold suction device. FIG. [Figure 7D]FIG. 13 is an explanatory diagram illustrating a state in which the ram of the mold suction device advances again and stops at a position where it has attracted the upper and lower molds. [Figure 7E] 11 is an explanatory diagram illustrating a state in which the ram of the mold suction device rotates to wind the tape supplied from the tape supplying device in contact with the side surfaces of the upper and lower molds around the side surfaces of the upper and lower molds. FIG. [Figure 7F] FIG. 13 is an explanatory diagram illustrating a state in which a mother mold is constructed after tape is wound around the side surfaces of the upper mold and the lower mold and the tape supplying device is retracted. [Figure 8] FIG. 13 is an explanatory diagram illustrating the positional relationship between the sag shape of the upper die and the contact tip of the backing plate. [Figure 9] FIG. 13 is an explanatory diagram for explaining the positional relationship between the sag shape of the upper die and the contact tip of the receiving plate when providing a predetermined down prism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a specific master mold holding device of the present invention, a method for positioning the master mold using the master mold holding device, and a method for winding tape around the master mold will be described with reference to the drawings. First, a mother mold holding device (hereinafter, the holding device) 1 will be described with reference to Figs. 1 to 6. The holding device 1 has a ring-shaped, flat aluminum alloy body 2 having a diameter of about 10 cm (12 cm in this embodiment). The front and back surfaces of the body 2 are a first set surface 4 for setting an upper mold 3 having a circular outer peripheral shape as a first mold, and a second set surface 6 for setting a lower mold 5 having a circular outer peripheral shape as a second mold. A through hole 7 that appears circular in a plan view is formed in the center of the body 2 from the first set surface 4 to the second set surface 6. A guide 8 is formed integrally with the body 2 on the periphery of the through hole 7 as a positioning means that rises in the axial direction of the body 2. The guide 8 is provided in the left and right directions in Fig. 1 with an angle width of about 75 degrees above and below the center of the body 2. The inner peripheral surface of the guide 8 is configured to be flush with the inner peripheral surface of the through hole 7. An outer wall portion 9 is formed integrally with the main body 2 on the outer periphery surrounding the first set surface 4 and the second set surface 6 outside the guide 8, rising to the same height as the guide 8 in the axial direction of the main body 2. The outer peripheral surface of the outer wall portion 9 is configured to be flush with the outer peripheral surface of the main body 2. The ring-shaped narrow area between the guide 8 and the outer wall portion 9 of the first set surface 4 and the second set surface 6 is a passage portion 10 formed parallel and horizontally. An upper mold holding plate 13 is fitted in a position facing 180 degrees across the through hole 7 of the passage portion 10 on the first set surface 4 side. The upper mold holding plate 13 is arranged in a step portion 11 formed facing the through hole 7 at the upper and lower positions between the two opposing guides 8. A lower mold holding plate 19 is fitted in a position facing 180 degrees across the through hole 7 of the passage portion 10 on the second set surface 6 side. The lower mold holding plate 19 is also arranged in the step portion 11 between the two opposing guides 8. First, the configuration around the upper die holding plate 13 on the first set surface 4 side will be described.

[0016] As shown in FIG. 1(a), a pair of upper and lower upper die holding plates 13 are disposed facing the upper and lower edges of the through hole 7 on the first set surface 4 side of the main body 2. As shown in FIG. 3(a) and (b), the aluminum alloy upper die holding plate 13 has a bow-shaped main body 15 configured with the same curvature as the curvature of the inner peripheral surface of the through hole 7. The main body 15 has three small through holes 16 formed therein, and is detachably attached to the screw holes 22 on the step portion 11 side by screws 17 through the small through holes 16. When the main body 15 is accommodated in the step portion 11, the upper surface of the main body 15 and the upper surface (horizontal plane L) of the passage portion 10 are flush with each other. Near both ends of the main body 15, receiving plates 18 are integrally formed with the main body 15 as protrusions protruding from the planar main body 15. The receiving plate 18 is arranged along the inner edge of the main body 15 by laying down a triangular prism so that the longitudinal direction of the ridge (joint of the faces) of the prism is arranged along the center line of the main body 2, and the corner of the innermost ridge is the abutment tip 18A. As shown in Fig. 6, the receiving plate 18 is arranged at angles that are rotationally symmetrical and mirror-symmetrical (in this embodiment, four positions of 55 degrees, 125 degrees, 250 degrees, and 305 degrees counterclockwise from the horizontal right direction in Fig. 1 as 0 degrees), and the upper mold 3 is supported by the four abutment tips 18A of the receiving plate 18 in the set state. The three-dimensional position (coordinates) of the abutment tip 18A on the holding device 1 is determined for each abutment tip 18A. A pair of upper and lower lower die holding plates 19 are disposed facing the upper and lower edges of the through hole 7 of the second set surface 6 . A pair of upper and lower lower die holding plates 19 are disposed facing the upper and lower edges of the through hole 7 on the second set surface 6 side of the main body 2. The lower die holding plate 19 differs from the upper die holding plate 13 in that the lower die holding plate 19 does not have a receiving plate 18, but in other respects has the same configuration as the upper die holding plate 13, so a detailed description of the similar configuration will be omitted. A mark 25 is provided by engraving, printing, attaching a sticker or the like on the upper surface of the passage portion 10 adjacent to the upper mold holding plate 13 (at a position adjacent to the step portion 11) which is the lower side in FIG. 1(a).

[0017] Next, a method for molding an inner surface progressive type meniscus lens-shaped progressive power lens using the holding device 1 will be described. Both the upper mold 3 and the lower mold 5 used in this embodiment are made of transparent glass. The upper mold 3 is a mold for forming the back surface (inner surface) that will be the progressive surface of the progressive power lens to be molded on the convex side. The lower mold 5 is a mold for forming the front surface (outer surface) that will be the spherical surface as the base curve of the progressive power lens to be molded on the concave side. As shown in FIG. 6, a mark 26 is provided at a position near the edge of the lower side (side where the near vision portion is molded) of the upper mold 3 to position the upper mold 3 in the circumferential direction by matching it with a mark 25 provided on the holding device 1 side. As shown in FIG. 4, the convex side of the upper mold 3 is set in the guide 8 of the first set surface 4 of the holding device 1, and the concave side of the lower mold 5 is set in the guide 8 of the second set surface 6. Since the upper die 3 is a mold for forming the progressive surface, the positional relationship between the upper die 3 and the contact tip 18A of the receiving plate 18 of the upper die holding plate 13 on which the upper die 3 is supported must be determined accurately. For this reason, the mark 26 provided on the upper die 3 side is matched with the mark 25 on the holding device 1 side. Since the inner circumference of the guide 8 and the outer circumference of the upper die 3 (and the lower die 5) match, the upper die 3 (and the lower die 5) is held in a predetermined position within the guide 8.

[0018] Here, the shape of the upper die 3 and the positional relationship of the contact tip 18A will be described with reference to FIGS. Since the upper die 3 is supported by four contact tips 18A of four support plates 18, the contact tips 18A are brought into contact with coordinates P1 to P4 on the back surface of the upper die 3, and as shown in Fig. 6, the support position in the 55 degree direction is designated as coordinate P1, followed by coordinates P2, P3, and P4 in the counterclockwise direction. Fig. 6 shows a state in which the contact tips 18A are in contact with positions 1.5 mm from the outer edge at coordinates P1 to P4 for an upper die 3 with a diameter of 66 mm as an example. As shown in FIG. 8, the abutting tip 18A is abutted against the coordinate P1 of the back surface of the upper die 3. The angle of the upper die 3 is adjusted in a simulation so that the desired down prism is expressed in the progressive power lens to be molded, and the coordinate value of the coordinate P1 is obtained. The difference between the coordinate of the reference plane of the sag when the back surface of the upper die 3 is produced and the horizontal plane L of the upper surface of the passage portion 10 (the horizontal plane L is also the height of the upper surface of the receiving plate 18 of the main body 15) is obtained. By adding this difference, the shape data of the abutting tip 18A on the horizontal plane L can be obtained. Alternatively, the calculation may be performed by matching the reference plane of the sag with the horizontal plane L. The coordinates P2 to P4 can also be obtained in the same way. Then, based on the obtained shape data, each receiving plate 18 is processed so that the abutting tip 18A matches the coordinates P1 to P4.

[0019] As shown in FIG. 5, the progressive power lens to be molded is set within the guide 8 of the first set surface 4 so as to support the four coordinates P1 to P4 of the upper mold 3 that will form the desired down prism, and the four abutting tips 18A of the four receiving plates 18, and the lower end portion on the concave side of the lower side 5 is set on the lower mold holding plate 19 which is configured to be flat.

[0020] Next, an example of a process from the holding device 1 in which the upper mold 3 and the lower mold 5 are temporarily fixed within the guide 8 to assembling the molds to form a mother mold will be described with reference to Figs. 7A to 7F. (1) The holding device 1 with the upper mold 3 and the lower mold 5 temporarily fixed is set on the table 31. As shown in Fig. 7A, in this state, the rams 32 of the suction device are positioned so as to directly face the upper mold 3 and the lower mold 5 of the holding device 1, respectively. (2) As shown in Fig. 7B, the ram 32 is advanced by a predetermined amount toward the holding device 1, and a vacuum device (not shown) is driven to strongly suction the upper mold 3 and the lower side 5 with the suction cups 33 at the tip of the ram 32. Next, as shown in Fig. 7C, with the upper mold 3 and the lower side 5 still suctioned by the suction cups 33, the ram 32 is retreated, and the temporarily fixed upper mold 3 and lower side 5 are released from the holding device 1, and the table 31 is retracted to move the holding device 1 away from the position where it interferes with the ram 32. (3) Next, as shown in FIG. 7D, the ram 32 is again moved in the forward direction and temporarily stopped at a predetermined position where the lens has a predetermined thickness. (4) As shown in Fig. 7E, the tape supplying device 35 is brought close to the outer end surfaces of the upper mold 3 and the lower side 5 so as to contact them, and the ram 32 is rotated in the circumferential direction with the tape 36 in contact. Then, as shown in Fig. 7F, the tape 36 is wound around the outer periphery of the upper mold 3 and the lower side 5. The tape 36 is cut by a tape cutter (not shown), and the tape supplying device 35 is removed, and a mother mold 37 having the upper mold 3 arranged at a predetermined angle to the lower side 5 can be obtained.

[0021] With this configuration, the present embodiment provides the following effects. (1) With regard to the upper and lower dies 3 and 5 used as molds for plastic molding of internal progressive power lenses, when the upper die 3, which molds the progressive surface side, is positioned at a predetermined inclination relative to the lower die 5 in relation to the holding device 1, it is supported at the contact tip 18A of the receiving plate 18 rather than at a surface. This does not complicate the shape of the holding device 1 side that supports the upper die 3, and makes it relatively easy to change the angle and hold any surface for molding any progressive surface. (2) The contact tips 18A of the receiving plate 18 are arranged at positions spaced apart from each other in a balanced manner, so that the upper die 3 is less likely to rattle when temporarily fixed. (3) The upper mold holding plate 13 is configured to be detachable from the holding device 1, so that it is easy to change to an upper mold 3 for a progressive power lens of another progressive design in which the shape of the receiving plate 18 is different. (4) The upper die 3 is placed in the guide 8, and the contact tip 18A of the receiving plate 18 is positioned at the predetermined coordinates by matching up the marks 25, 26, so that the positioning of the upper die 3 is easy and error-free.

[0022] Next, an embodiment of a progressive power lens molded using the mother die 37 thus constructed will be described. In the embodiment, a progressive power lens with a lens diameter of 60 mm was molded with a mold diameter of 66 mm. The target prism amount of the molded lens was a down prism of 0.4. As shown in the left diagram of FIG. 9, in the design for molding a progressive power lens with a down prism of 0, the sag amount at a certain point A in the distance portion of the upper mold 3 was 2.65 mm, and the sag amount at a certain point B in the near portion was 1.97 mm. When the progressive surface was designed again to give a down prism of 0.4 to the lens to be molded, the sag amount at point A was 2.46 mm, and the sag amount at point B was 2.15 mm, as shown in the center diagram of FIG. 9. With a conventional holding device, the upper mold 3 is set on a flat surface such as the upper mold holding plate 13 on which the support plate 18 is not formed, and the sag amount of the distance portion is greater than that of the near portion, so it is set tilted in the direction of the arrow more than the actual 2.46 mm. However, in this embodiment, it is supported by the abutting tip 18A of the support plate 18, and is held at a sag position of 2.46 mm as shown in the right diagram of Figure 9, so the planned down prism of 0.4 should be obtained. Table 1 shows examples of four progressive power lenses, A to D, which are designed with an addition power of -1.00 and have different near vision powers. Four different upper molds 3 and upper mold holding plates 13 were replaced for each upper mold 3 to form mother molds 37, and four types of progressive power lenses were obtained by cast finishing. Measurements were made on these cast-finished lenses (CF lenses), and all of the progressive power lenses obtained a down prism of around 0.4, which was close to the target.

[0023] [Table 1]

[0024] The above embodiment is merely described as a specific embodiment for illustrating the principle and concept of the present invention. In other words, the present invention is not limited to the above embodiment. The present invention can be embodied in the following modified forms, for example. The above number of upper dies 3 (contact tips 18A) is one example. It may be more or less. In the above, the entire convex surface of the upper die 3 is supported by the support plate 18, but for example, only the upper region of the upper die 3 may be supported by the support plate 18. In the above description, the contact tips 18A are disposed at positions corresponding to the upper and lower far-use and near-use areas, but they may be disposed in areas other than these. The above is one example of the shape of the receiving plate 18. As long as the coordinates can be determined with a shape that provides a contact tip, the shape is not limited to the above. For example, the receiving plate may be shaped like a triangular pyramid, a square pyramid, or a cone that has a contact tip. Also, since it is only necessary for the receiving plate 18 to contact the upper die 3 at a "point", the receiving plate 18 may be a rounded protrusion such as a dome. The configuration of the holding device 1 is not limited to that described above. The area in which the guide 8 is formed and the size of the through hole 7 may be changed, or the through hole 7 may not be present. The above-mentioned process from the holding device 1 to assembling the mold to construct the mother mold is one example. The mother mold may be constructed through other processes. For example, the tape may be wound by hand. In the above embodiment, an example was described in which a down prism is provided to the lens, but the present invention is also applicable to the case in which an up prism is provided.

[0025] The present invention is not limited to the configurations described in the above embodiments. The components of each embodiment and modification may be arbitrarily selected and combined. Any component of each embodiment or modification may be arbitrarily combined with any component described in the Summary for Solving the Problems of the Invention, or any component that embodies any component described in the Summary for Solving the Problems of the Invention. We intend to obtain rights to these as well through amendments or divisional applications of this application. In addition, the applicant intends to obtain rights to the overall design or partial design by filing a conversion application to a design application. The drawings show the entire device in solid lines, but they also include partial designs claimed for a portion of the device as well as the overall design. For example, a partial design may include a portion of the device as a partial design, regardless of the portion. A portion of the device may be a portion of the device, or may be a part of that portion. [Explanation of symbols]

[0026] 1...mold holding device for mother mold, 2...main body, 3...upper mold as first mold, 5...lower mold as second mold, 8...guide as positioning means, 18 (18A)...receiving plate (contact tip) as first holding part, 19...lower mold holding plate as second holding part.

Claims

1. A mother mold holding device for holding a mother mold used in plastic molding of an inner surface progressive meniscus lens-shaped progressive power lens, comprising: a body in which a first mold for molding a back surface of the progressive power lens and a second mold for molding a front surface of the progressive power lens are disposed; a positioning means for holding the rear molding surface of the first mold and the front molding surface of the second mold in an opposing state on the main body; a first holding portion for supporting an edge or a portion close to the edge of the rear molding surface of the first mold, and a second holding portion for supporting an edge or a portion close to the edge of the front molding surface of the second mold, for holding the first mold and the second mold opposed to each other by the positioning means at a distance; 4. A mother mold holding device, wherein the first holding portion is constituted by a plurality of protrusions.

2. 2. The mother mold holding device according to claim 1, wherein the plurality of protrusions are arranged in a plurality of spaced apart regions on the edge or near the edge of the rear molding surface of the first mold.

3. 2. The mother mold holding device according to claim 1, wherein the plurality of protrusions are arranged in two regions on the opposite edges or near edges of the rear molding surface of the first mold.

4. 4. The mother mold holding device according to claim 3, wherein the two regions are provided along a direction for molding the vertical direction of a progressive power lens at the edge or a portion near the edge of the rear molding surface of the first mold.

5. 5. The master mold holding device according to claim 1, wherein the protrusions are detachable from the main body.

6. A method for arranging a master mold for plastic molding of an inner surface progressive type meniscus lens shaped progressive power lens, comprising the steps of: a rear surface molding surface of a first mold for molding the rear surface of the progressive addition lens and a front surface molding surface of a second mold for molding the front surface of the progressive addition lens are arranged opposite each other, and when the opposed first and second molds are held at a distance from each other, an edge portion of the rear surface molding surface of the first mold is supported by a plurality of protrusions, and an angle of the first mold relative to the second mold is determined based on coordinate values ​​at a position where the protrusions abut against the first mold.

7. 7. The method for positioning a master mold according to claim 6, wherein the arrangement angle of the first mold with respect to the second mold is determined in accordance with a prism amount of a progressive power lens to be molded.

8. 8. A method for wrapping tape around a master mold, comprising: acquiring and storing data on the relative distance and posture of the first and second molds to be used as master molds by the method for positioning a master mold as claimed in claim 6 or 7; catching the first mold and the second mold with a catching means, respectively, and separating them temporarily; and then arranging the first mold and the second mold opposite each other at a predetermined position based on the data; and creating a master mold by wrapping adhesive tape around the outer periphery of the first mold and the second mold in this state.

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