JP2007322834A - Molded lens integrated with holding barrel and its manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem in an achromatic lens manufactured by the conventional manufacturing method that the strength thereof is low against external force from an outer periphery direction, and respective laminated lenses therein have a different thermal expansion coefficient generally, consequently they are easily separated even due to small temperature change. <P>SOLUTION: The molded lens integrated with the holding barrel is constituted of the holding barrel 4 forming a hot working space together with upper and lower molding metallic dies 1 and 2 when molding, and a lens main body molded in the holding barrel, and the lens main body is constituted by laminating the lenses 7 and 8 made of a plurality of lens materials having different molding temperature. Such a molded lens and its manufacturing device are proposed. The molded lens is easily manufactured even when it is a lens thin in thickness and a lens having a surface made aspherical. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a molded lens used in an optical instrument such as an endoscope used in the medical field, and more particularly to a molded lens in which a plurality of lens materials are laminated and a manufacturing apparatus therefor.

  In order to suppress chromatic aberration, an imaging lens uses an achromatic lens in which a plurality of lenses having a small dispersion and a lens having a large dispersion are bonded together. As a common name, a lens having two lenses bonded together is called a doublet, and a lens having three lenses bonded together is called a triplet.

Conventionally, these achromatic lenses made of glass are manufactured through, for example, the following steps in sequence.
1. Single Lens Polishing Process After a glass base material is press-molded into a shape that approximates the target lens shape, it is roughly rubbed with a curve generator, and after finishing with sanding, final polishing is performed with a polishing machine.
2. Centering process The lens produced in the previous process is attached to the rotation axis of the spindle, centered so that the optical axis coincides with the rotation axis, and the outer periphery of the lens is polished with a diamond grindstone.
3. Optical axis adjustment process The optical axes of the two or three lenses that have undergone the previous process are precisely matched using a centering microscope.
4). Bonding process Two or three lenses that are precisely centered in the previous process are bonded with a synthetic resin adhesive having high heat resistance.
5). Metal frame fixing step Positioning is performed so that all the optical axes of the two or three lenses joined in the previous step are exactly coincident with each other and fixing in a cylindrical metal frame processed with high accuracy.

On the other hand, as another manufacturing method, in Patent Document 1, a first lens base material is hot-worked with a first and second pair of molds and a barrel mold to mold a first lens, and then a second By removing the mold and installing the second lens base material and the third mold and hot forming to form a lens that is bonded and laminated with two or more lenses, and a method for manufacturing the same Has been.
JP-A-11-130448

In the above prior art, first, a plurality of single lenses produced in a desired shape by polishing are bonded and laminated with an adhesive after adjusting the optical axis, there are the following problems.
1. Costs are high due to many manufacturing processes and high-precision processing techniques.
2. Since a lens having a target shape is manufactured by polishing, it is difficult to manufacture a lens having a small lens outer diameter or a lens having a thin lens thickness, and it is also difficult to make the lens surface aspherical.
3. After manufacturing the laminated lens, the optical axis of the lens is accurately adjusted and attached to the lens barrel of the imaging system, so this process also requires high-precision processing technology, which has resulted in increased costs. .

In addition, the lens manufactured by the manufacturing method described in Patent Document 1 has a low strength against external force from the outer peripheral direction, and generally has a different coefficient of thermal expansion, so that it can be separated even by a slight temperature change. Cheap.
The present invention aims to solve the conventional problems described above.

  In order to solve the above problems, the present invention first comprises a holding cylinder that forms a hot working space together with upper and lower molding dies at the time of molding, and a lens body molded in the holding cylinder. Proposes a molded lens in which a holding cylinder having a configuration in which lenses of a plurality of lens materials having different molding temperatures are laminated is integrated.

  In the present invention, in the above-described configuration, the lens body is formed by laminating a lens made of a lens material having a low molding temperature, with the lens surface of the lens material having a high molding temperature previously molded as one mold. Propose that

  The present invention also proposes a molded lens in which the lens body is composed of two, three, or four or more laminated lenses in the above configuration.

  In the present invention, it is proposed that, in the above-described configuration, the holding cylinder is made of a material having a thermal expansion coefficient equal to or larger than the largest thermal expansion coefficient of a plurality of laminated glasses.

  In the present invention, the lens material may be glass or plastic.

  In addition, the present invention proposes a molded lens in which the surface of at least one side of the molded lens, that is, only one side or both sides is formed in an aspherical shape.

  Further, in the present invention, in an apparatus for manufacturing a molded lens by hot working a lens base material with a molding die composed of a trunk mold and an upper mold and a lower mold arranged in the trunk mold, A molded lens that has a structure in which a holding cylinder that forms a hot working space together with a lower mold is supported in a body mold, and at least one side of the upper mold and the lower mold is integrated with a plurality of interchangeable molds We propose a manufacturing device.

  In the manufacturing apparatus according to the present invention, a lens formed by stacking lenses by hot working a lens base material in a hot working space constituted by an upper die and a lower die arranged in a body die and a holding cylinder. Since the molded lens with the main body integrated in the holding cylinder is manufactured, it is not necessary to polish each lens and adjust the optical axis, and the lens with a small lens outer diameter, a lens with a thin lens thickness, and a lens surface are not covered. Even a spherical lens can be easily manufactured.

  That is, a lens body composed of laminated lenses can be easily manufactured by molding a lens material having a low molding temperature using the lens surface of the lens material having a high molding temperature previously molded as one mold, Each lens is integrated with the holding cylinder together with molding.

  As described above, in the molded lens according to the present invention, the laminated lenses are integrated with the holding cylinder together with the molding. Therefore, the outer periphery of the lens is protected by the holding cylinder, and the laminated lenses are not easily separated.

  In this case, when the holding cylinder is made of a material larger than the largest thermal expansion coefficient of the plurality of lens materials to be laminated, the holding cylinder has a plurality of force in the contraction direction at the operating temperature after hot working. Since this acts in the direction opposite to the direction in which the lens is separated, the lens is further prevented from being separated.

  The molded lens of the present invention can be easily attached to the imaging system by using the holding cylinder as a lens barrel because the optical axes of the holding cylinder and the respective lenses are accurately adjusted at the time of molding the lens. And can be performed accurately.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 5 show a first embodiment of a molded lens and a manufacturing apparatus thereof according to the present invention, that is, a molded lens having a two-layer lens made of a glass material.
1 to 4 are sectional views showing a manufacturing apparatus and a molded state of the lens, and FIG. 5 is a sectional view of a molded lens manufactured by molding.
In these drawings, reference numeral 1 is an upper mold, 2 is a lower mold, and 3 is a trunk mold. The upper die 1 and the lower die 2 are formed with large-diameter portions 1a and 2a that fit inside the barrel die 3 and thin-diameter portions 1b and 2b that fit inside the holding cylinder 4 described below. Molded portions 1c and 2c corresponding to the surface shape of the lens to be molded are formed at the tips of the diameter portions 1b and 2b.
On the upper side of the lower mold 2, a spacer 5 having an outer periphery fitted into the inner side of the body mold 3 and provided with a fitting hole for fitting into the small-diameter portions 1 b and 2 b at the center is mounted. A recess 6 for fitting the holding cylinder 4 from above is formed. In the above configuration, the upper mold 1 is supported so as to be movable up and down along the trunk mold 3.

  As described above, reference numeral 4 denotes a holding cylinder, and the holding cylinder 4 is mounted from above on the gap between the recess 6 and the small diameter portions 1b and 2b. The holding cylinder 4 is made of a material whose thermal expansion coefficient is equal to or larger than the largest thermal expansion coefficient of a plurality of lens materials to be laminated. For example, the holding cylinder 4 is made of metal such as SUS304, SUS430, and 50% Ni-Fe. is there.

  In the above configuration, as shown in FIG. 1, the holding cylinder 4 is mounted from above on the gap between the concave portion 6 and the small diameter portions 1 b and 2 b, and the first lens 7 is formed on the molding portion 2 c of the lower mold 2. The first lens base material 7a for molding the first lens is placed, then the upper mold 1 is lowered in the body mold 3, and the small diameter portion 1b is fitted into the holding cylinder 4, so that the first lens is formed. The base material 7a is positioned between the molding parts 1c and 2c.

  In this state, a space formed by the molding part 1c of the upper mold 1, the molding part 2c of the lower mold 2 and the holding cylinder 4 is used as a hot working space, and the first die is formed by hot working while lowering the upper mold 1. The lens base material 7a is heat-molded to mold the first lens 7 as shown in FIG.

  Next, the upper mold 1 is raised and removed, and a second lens base material 8a for molding the second lens 8 is placed on the upper side of the first lens 7 molded in the previous step, and the upper mold is placed. 1 is replaced with the upper mold 1 having a molding part 1d corresponding to the surface shape of the second lens 8, and descends, so that the second lens base material 8a is replaced with the molding part 1d and the lens 7 as shown in FIG. Between the top surfaces of

  In this state, the space formed by the molding part 1d of the upper mold 1, the upper surface of the lens 7 and the holding cylinder 4 is a hot working space, and the hot working is performed at a temperature lower than the molding temperature required for molding the first lens 7. When the second lens base material 8a is heat-molded by processing, the second lens 8 is molded with the upper surface of the first lens 7 as a mold on one side, and the first lens 7 and the second lens 8 are formed as shown in FIG. A lens in which the lenses 8 are laminated is molded.

  After the above molding, the upper mold 1 is raised and the holding cylinder 4 is removed from the recess 6 to stack the first lens 7 and the second lens 8 as shown in FIG. , 8 is obtained by integrating the holding cylinder 4 on the outer peripheral side.

  In this lens, the laminated lenses 7 and 8 are integrated with the holding cylinder 4 at the same time as the molding, so that the outer periphery of each lens 7 and 8 is protected by the holding cylinder 4. It is difficult to separate the lenses 7 and 8 due to the integration.

  In particular, when the holding cylinder 4 is made of a material such as a metal whose thermal expansion coefficient is larger than the thermal expansion coefficient of each lens material constituting the lenses 7, 8, the holding cylinder 4 is At this operating temperature, the lens 7 and 8 tend to contract more, so the force in the contraction direction acts in the direction opposite to the direction in which the lenses 7 and 8 are separated, and the lenses 7 and 8 are not strongly separated. Can be held.

  In the molded lens of the present invention, since the optical axes of the holding cylinder and the respective lenses are accurately adjusted simultaneously with the molding of the lenses 7 and 8, the holding cylinder is used as a lens barrel so that it can be attached to the imaging system. It can be done easily and accurately.

Next, FIGS. 6 to 10 relate to the second embodiment of the molded lens and the apparatus for manufacturing the same according to the present invention, particularly to a molded lens having three layers of lenses.
6 to 9 are cross-sectional views showing the manufacturing apparatus and the molded state of the lens, and FIG. 10 is a cross-sectional view of the formed lens.
In these drawings, reference numeral 11 is an upper mold, 12 is a lower mold, and 13 is a trunk mold. The upper mold 11 and the lower mold 12 are formed with large-diameter portions 11a and 12a that fit inside the trunk mold 13 and thin-diameter portions 11b and 12b that fit inside the holding cylinder 14, respectively. Molded portions 11c and 12c corresponding to the surface shape of the lens to be molded are formed at the tips of the portions 11b and 12b.
On the upper side of the lower mold 12, there is provided a spacer 15 for disposing a holding cylinder 14 having an outer periphery fitted inside the barrel mold 13 and having a fitting hole fitted in the center of the small diameter portions 11b and 12b. A recess 16 for fitting the holding cylinder 14 from above is formed in the fitting hole. In the above configuration, the upper mold 11 and the lower mold 12 are supported so as to be movable up and down along the body mold 13.

  As described above, reference numeral 14 denotes a holding cylinder, and the holding cylinder 14 is attached to the gap between the concave portion 16 and the small diameter portions 11b and 12b from above. Similar to the first embodiment, the holding cylinder 14 is made of a material whose thermal expansion coefficient is equal to or larger than the largest thermal expansion coefficient of the plurality of lens materials to be laminated. For example, SUS304, SUS430, Made of metal such as 50% Ni-Fe.

  In the above configuration, as shown in FIG. 6, the holding cylinder 14 is mounted from above on the gap between the concave portion 16 and the small diameter portions 11 b and 12 b, and the lower mold 12 is mounted on the holding cylinder 14. Then, the first lens base material 17a for molding the first lens 17 is placed on the molding portion 12c. Next, the upper mold 11 is lowered in the body mold 13, the small diameter portion 11 b is fitted into the holding cylinder 14, and the first lens base material 17 a is positioned between the molding portions 11 c and 12 c.

  In this state, a space formed by the molding part 11c of the upper die 11, the molding part 12c of the lower die 12 and the holding cylinder 14 is a hot working space, and the first die is obtained by hot working while lowering the upper die 11. The lens base material 17a is thermoformed to form the first lens 17 as shown in FIG.

  Next, the upper mold 11 is raised, the lower mold 12 is lowered and removed, and the upper mold 11 and the lower mold 12 are molded portions 11d and 12d corresponding to the surface shapes of the second and third lenses 18 and 19, respectively. Replace with one that has In the lower mold 12, the inside of the body mold 13 is raised in a state where the third lens base material 19a for forming the third lens 19 is placed on the molding portion 12d, and the upper part of the lens base material 19a is in front. The position is close to the lower surface of the first lens 17 formed in the process. In addition, after placing the second lens base material 18 a for forming the second lens 18 on the upper surface of the first lens 17, the upper mold 11 has a molding portion corresponding to the surface shape of the second lens 18. The upper die 11 having 11d is replaced and lowered to place the second lens base material 18a between the molding portion 11d and the upper surface of the lens 17 as shown in FIG. At this time, the molding unit 11d stops at a position where it does not give an impact to the lens 17 manufactured in the previous process via the second lens base material 18a.

  In this state, the space formed by the molding portion 11d of the upper mold 11, the upper surface of the lens 17 and the holding cylinder 14 and the space formed by the molding portion 12d of the lower mold 12, the lower surface of the lens 17 and the holding cylinder 14 are heated. As an inter-processing space, at a temperature lower than the molding temperature required for molding the first lens 17, the second lens base material 18a and the third lens 18a and the third lens are hot-worked while lowering the upper die 11 and raising the lower die 12. When the lens base material 19a is heat-molded, the second lens 18 and the third lens 19 are molded with the upper surface and the lower surface of the first lens 17 as molds on one side, respectively, and the first lens 17 as shown in FIG. A lens in which the second lens 18 and the third lens 19 are laminated on both sides of the lens 17 is molded.

  After the above molding, the upper mold 11 is raised, and the holding cylinder 14 is removed from the concave portion 16, whereby the second lens 18 and the third lens are respectively formed on both sides of the first lens 17 as shown in FIG. A lens 19 is laminated, and a lens in which these lenses 17, 18 and 19 are integrated with the holding cylinder 14 on the outer peripheral side is obtained.

  Similarly to the first embodiment, the lenses 17, 18, and 19 are integrated with the holding cylinder 14 at the same time as the molding, so that these lenses 17, 18, and 19 are integrated with each other. The outer periphery is protected by the holding cylinder 14, and the lenses 17, 18, and 19 are not easily separated by integration with the holding cylinder 14.

  In particular, when the holding cylinder 14 is made of a material such as a metal whose thermal expansion coefficient is larger than that of each lens material constituting the lenses 17, 18 and 19, the holding cylinder 14 is hot. At the use temperature after processing, the lens 17, 18 and 19 tend to contract more than the lens 17, 18 and 19, so that the force in the contraction direction acts in the direction opposite to the direction in which the lenses 17, 18 and 19 are separated. 19 can be firmly held so as not to leave.

  As in the first embodiment, in this molded lens, the holding cylinder 14 and the optical axes of the lenses 17, 18 and 19 are accurately adjusted simultaneously with the molding of the lenses 17, 18 and 19, so By using the tube 14 as a lens barrel, it can be easily and accurately attached to the imaging system.

  In the above second embodiment, three lenses are laminated by laminating lenses on both sides of the first molded lens 17, but in addition to this, in the first embodiment, two lenses are laminated. After the lenses are laminated, lenses can be further laminated to produce a molded lens in which three lenses are laminated. However, in this case, since the lens material for molding each lens needs to be sequentially lowered in molding temperature, the material selection range is narrowed.

  In addition, although the molded lens of the above embodiment is two laminated lenses and three laminated lenses, more than that can be laminated.

Examples of the molded lens manufactured in the first embodiment are as follows. In this case, the lens material is glass, and the molding temperature T is set appropriately between the glass transition point Tg and the glass softening point SP (Tg ≦ T ≦ SP).
Holding cylinder: Outer diameter φ3mm
First lens: N-SF66 (T: 790 ° C), outer diameter φ2.1mm, wall thickness 0.8mm
Second lens: L-BSL7 (T: 600 ° C), outer diameter φ2.1mm, wall thickness 1.56mm
In the above molded lens, when the surface shape on both sides of the lens is a spherical shape, when a parallel beam with a diameter of 1.4 mm is condensed by the lens, the diameter of the collected beam is 2.6 μm. If it is an aspherical shape, the diameter of a beam obtained by condensing a parallel beam having a diameter of 1.4 mm with a lens can be 2 μm.
In the method using the polishing described above as a conventional example, it is difficult to make the surface shape of the lens an aspherical surface, but in the present invention, the lens is manufactured by hot working the lens base material with a molding die. Therefore, it is easy to obtain an aspherical shape, and it is possible to enjoy a number of advantages due to the aspherical shape.

Examples of the molded lens produced in the second embodiment are as follows. In this case, the lens material is glass, and the molding temperature T is set appropriately between the glass transition point Tg and the glass softening point SP (Tg ≦ T ≦ SP).
Holding cylinder: Outer diameter φ3mm
First lens: N-BK7 (T: 680 ℃), outer diameter φ2.1mm, wall thickness 1.5mm
Second lens: SF66 (T: 450 ° C), outer diameter φ2.1mm, wall thickness 0.85mm
Third lens: SF66 (T: 450 ° C), outer diameter φ2.1mm, wall thickness 0.5mm

  A separation test is performed on the molded lens manufactured in the first embodiment of the present invention and the molded lens (each lens outer diameter φ2 mm) in which only the lens is laminated without the holding cylinder by the conventional manufacturing method such as Patent Document 1. In the molded lens according to the conventional method, when a compressive force of about several hundred gf is applied in the outer circumferential direction of the molded lens, the two lenses are separated. In the molded lens of the present invention, the outer circumferential direction of the holding cylinder is separated. Even when a force of about 10 kgf was applied, it was not separated. From this, it can be seen that in the present invention, a doublet having high bonding strength can be formed even when a glass base material containing no lead, which has poor wettability of the glass during press molding, is used.

  As a result of a heat cycle test in which the molded lens produced in the first embodiment of the present invention was held at −40 ° C. and + 85 ° C. for 15 minutes and the temperature rise / fall temperature was 1 ° C./min for 100 cycles, Before and after, it was possible to mold a doublet resistant to temperature changes without deteriorating both the lens shape and lens characteristics.

The glass transition point Tg and softening point SP of the glass as each lens material used in the above examples are as follows.
Lens material Glass transition point Tg Glass softening point SP Molding temperature T
N-SF66 710 ° C 806 ° C 790 ° C
L-BSL7 498 ° C 630 ° C 600 ° C
N-BK7 557 ° C 719 ° C 680 ° C
SF66 384 ° C 482 ° C 450 ° C

Since the present invention is as described above, there are many effects as described below, and the possibility of implementation is great.
1. In the manufacturing apparatus according to the present invention, a lens formed by stacking lenses by hot working a lens base material in a hot working space constituted by an upper die and a lower die arranged in a body die and a holding cylinder. Since the molded lens with the main body integrated in the holding cylinder is manufactured, it is not necessary to polish each lens and adjust the optical axis, and the lens with a small lens outer diameter, a lens with a thin lens thickness, and a lens surface are not covered. Even a spherical lens can be easily manufactured.
2. As described above, in the molded lens according to the present invention, the laminated lenses are integrated with the holding cylinder together with the molding. Therefore, the outer periphery of the lens is protected by the holding cylinder, and the laminated lenses are not easily separated.
3. In this case, when the holding cylinder is made of a material larger than the largest thermal expansion coefficient of the plurality of lens materials to be laminated, the holding cylinder has a plurality of force in the contraction direction at the operating temperature after hot working. Since this acts in the direction opposite to the direction in which the lens is separated, the lens is further prevented from being separated.
4). The molded lens of the present invention can be easily attached to the imaging system by using the holding cylinder as a lens barrel because the optical axes of the holding cylinder and the respective lenses are accurately adjusted at the time of molding the lens. And can be performed accurately.
5). Since it is easy to make the surface shape of a lens into an aspherical shape, a number of advantages can be obtained.
6). Small and highly accurate so-called doublets and triplets that could not be produced by conventional manufacturing methods can be provided at low cost, especially for applications that require miniaturization, such as endoscopes used in the medical field. Great effect.

It is sectional drawing showing the component and operation | movement of 1st Embodiment of the molded lens of this invention, and its manufacturing apparatus explanatory. It is sectional drawing which represented the component and operation | movement of 1st Embodiment of the shaping | molding lens of this invention and its manufacturing apparatus which demonstrated in another situation. It is sectional drawing which expressed the component and operation | movement of 1st Embodiment of the shaping | molding lens of this invention and its manufacturing apparatus which demonstrated in another situation further. It is sectional drawing which expressed the component and operation | movement of 1st Embodiment of the shaping | molding lens of this invention and its manufacturing apparatus which demonstrated in another situation further. It is sectional drawing of the shaping | molding lens shape | molded by the 1st Embodiment of this invention. It is sectional drawing showing the component and operation | movement of 2nd Embodiment of the molded lens of this invention, and its manufacturing apparatus explanatory. It is sectional drawing which represented the component and operation | movement of 2nd Embodiment of the shaping | molding lens of this invention, and its manufacturing apparatus in other aspects. It is sectional drawing which represented the component and operation | movement of 2nd Embodiment of the shaping | molding lens of this invention, and its manufacturing apparatus in description in further another situation. It is sectional drawing which represented the component and operation | movement of 2nd Embodiment of the shaping | molding lens of this invention, and its manufacturing apparatus in description in further another situation. It is sectional drawing of the shaping | molding lens shape | molded by the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Upper mold | type 2,12 Lower mold | type a Large diameter part b Small diameter part c, d Molding part 3, 13 Body type | mold 4,14 Holding cylinder 5,15 Spacer 6,16 Concave part 7,17 1st lens 8, 18 Second lens 9, 19 Third lens a Lens base material

Claims (9)

  It consists of a holding cylinder that forms a hot working space together with the upper and lower molding dies at the time of molding, and a lens body molded in the holding cylinder. The lens body is made up of lenses made of a plurality of lens materials with different molding temperatures. A molded lens integrated with a holding cylinder, characterized in that it has the same structure.   2. The lens body according to claim 1, wherein a lens made of a lens material having a low molding temperature is molded and laminated with the surface of the lens material having a high molding temperature molded in advance as one mold. Molded lens with integrated holding cylinder.   3. The molded lens integrated with a holding cylinder according to claim 1 or 2, wherein the lens body is composed of two laminated lenses.   3. The molded lens integrated with a holding cylinder according to claim 1, wherein the lens body is composed of three stacked lenses.   3. The molded lens integrated with a holding cylinder according to claim 1, wherein the lens body is composed of four or more laminated lenses.   The holding cylinder is made of a material whose thermal expansion coefficient is equal to or larger than the largest thermal expansion coefficient of a plurality of lens materials to be laminated. Molded lens with integrated holding cylinder.   The lens material is glass, and a molded lens integrated with the holding cylinder according to any one of claims 1 to 6.   The molded lens integrated with the holding cylinder according to any one of claims 1 to 7, wherein a surface of at least one side of the molded lens is formed in an aspherical shape. In a device that manufactures a molded lens by hot-working a lens base material with a molding die consisting of a barrel mold and an upper mold and a lower mold arranged in the barrel mold, it is hot together with the upper mold and the lower mold during molding. A molded lens with an integrated holding cylinder, wherein the holding cylinder forming the processing space is supported in the body mold, and at least one of the upper mold and the lower mold is composed of a plurality of interchangeable molds. Manufacturing equipment.

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