JP2009037055A - Optical element with lens barrel and metallic die for molding optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element with a lens barrel coping with the volume error of optical material without spoiling attaching accuracy, airtightness and attaching strength. <P>SOLUTION: A holder optical element 5 is equipped with: a lens barrel 2 which has cylindrical shape and where a recessed part 2a is formed on the inside surface of the cylindrical shape; and an optical element 1 held in the lens barrel 2. The optical element 1 includes: a lens part 1a having an optical functional surface; an edge part 1b formed on the outer periphery of the lens part 1a and butting against the lens barrel 2; and a periphery part 1c formed on the outer periphery of the edge part 1b and holding the optical element 1 by getting into the recessed part 2a of the lens barrel 2. The recessed part 2a of the lens barrel 2 is set so that the width (a) of the recessed part 2a in the optical axis direction of the optical element 1 has a relation of a>c to the thickness (c) of the edge part 1b of the optical element 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element with a lens barrel and an optical element molding die for molding the optical element with a lens barrel.

Optical elements such as lenses used in optical communications, lenses mounted on DVD (Digital Versatile Disk) pickup heads (optical pickups) and lenses used in digital cameras have high mounting accuracy, airtightness, and mounting. Strength is required. In order to satisfy such requirements, an optical element with a lens barrel is adopted in which a part of the optical element is embedded in a lens barrel and integrated. Then, press molding using a molding die is employed for manufacturing the optical element with the lens barrel.
However, if there is a volume error in the optical material supplied to the molding die, the thickness of the optical element changes and the originally designed optical performance cannot be realized. For example, in Japanese Patent Application Laid-Open No. 2004-26883, a concave portion is formed on the inner peripheral surface of a lens barrel as a technique disclosed in Japanese Patent Application Laid-Open No. 2005-260260 that absorbs a volume error of an optical material supplied to a molding die and realizes a desired optical performance. A surplus part protruding outward is formed in the element, and the surplus part of the optical element is absorbed by the recess on the inner peripheral surface of the lens barrel.

Japanese Patent Laid-Open No. 2004-271784

By the way, when the lens is fixed to the lens barrel by embedding a part of the optical element in the concave portion formed on the inner peripheral surface of the lens barrel, air may remain in the concave portion to form a large gas reservoir. When used in a harsh environment or for a long period of time, the air in the gas reservoir may leak and the airtightness may be impaired. Further, when the gas reservoir is formed, the glass component does not enter the recess, so that the amount of catch between the lens and the lens barrel is reduced, and the attachment strength between the lens barrel and the lens is reduced. There is also a risk of deformation of the optical element or dropping from the lens barrel.
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical element with a lens barrel that can cope with a volume error of an optical material without impairing mounting accuracy, airtightness, and mounting strength.

  In order to solve the above-described problems, an optical element with a lens barrel according to the present invention includes a lens barrel having a cylindrical shape and a concave portion formed on an inner side surface of the cylinder, and a lens body held by the lens barrel. The lens body includes a lens part having an optical function surface, an edge part formed on the outer periphery of the lens part and abutted against the lens barrel, and formed on the outer periphery of the edge part and entering the recess of the lens barrel. And the concave part of the lens barrel has a relation that the width a of the concave part in the optical axis direction of the lens body is a> c with respect to the thickness c of the edge part of the lens body. And

Here, in the edge portion of the lens body, any one surface of the edge portion is inside the concave portion of the lens barrel in the optical axis direction, and the other surface of the edge portion is outside the concave portion in the optical axis direction. If it is characterized, it is difficult to form an air pocket in the concave portion of the lens barrel, and as a result, a catching distance between the lens body and the lens barrel is secured, and mounting strength can be secured, which is preferable.
Further, when the volume f of the concave portion of the lens barrel is set, the optical material supplied for press molding of the optical element has a volume e obtained by subtracting the sum of the volumes of the lens body and the edge portion from the total volume of the optical material. 0.833 × f <e <1.25 × f, the optical material to be placed is not excessive or insufficient, and the distance between the lens body and the lens barrel is secured and the mounting is ensured. It is preferable because strength can be secured.

  In order to solve the above-described problems, an optical element with a lens barrel according to the present invention has a cylindrical shape, a lens barrel in which concave portions are formed on the entire inner surface of the cylindrical shape, and a lens held by the lens barrel. And a lens body having an optical functional surface, an edge portion formed on the outer periphery of the lens portion and abutted against the lens barrel, and formed on the outer periphery of the edge portion, and entering the concave portion of the lens barrel. The edge portion of the lens body overlaps with a part of the recess of the lens barrel in the optical axis direction of the lens body and does not overlap with the other part.

  In order to solve the above problems, an optical element molding die according to the present invention includes an optical function surface molding surface that molds an optical function surface of a lens body included in an optical element with a lens barrel, and an outer periphery of the optical function surface molding surface. And a pair of fixed molds and movable molds having a molding part for molding the edge part of the lens body. The fixed mold and the movable mold are arranged to face each other inside the lens barrel having a recess formed in the periphery, and the fixed mold and the movable mold press the optical material, and a part of the pressed optical material In the optical element molding die that press-molds the lens body that is held and fixed in the concave portion of the lens barrel, the movable die that slides in the lens barrel corresponds to the concave portion of the lens barrel. Further, a relief portion for absorbing excess optical material is formed.

  Here, the edge molding surface of the fixed mold is arranged outside the concave portion of the lens barrel in the optical axis direction of the lens body, and the edge molding surface of the movable mold is inside the concave portion of the lens barrel in the optical axis direction. It is difficult to form an air pocket in the recess of the lens barrel, and as a result, the catch distance between the lens body and the lens barrel is secured and the mounting strength is increased. It is preferable because it can be secured.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element with a lens-barrel etc. which can respond to the volume error of an optical material can be provided, without impairing attachment accuracy, airtightness, and attachment strength.

Hereinafter, the best mode (embodiment) for carrying out the present invention will be described in detail.
FIG. 1 is a cross-sectional view of a holder optical element 5 as an example of an optical element with a lens barrel according to the present embodiment.
As shown in FIG. 1, the holder optical element 5 includes an optical element 1 as an example of a lens body that focuses incident light and forms an image at a focal position, thereby preventing stray light from entering. 1 is attached to a lens barrel 2 that protects 1.

The optical element 1 is made of, for example, low melting point glass containing silica as a main component and added with, for example, alumina, sodium, lanthanum fluoride, or the like. The optical element 1 may be made of, for example, a low-melting glass having a softening temperature of about 600 ° C. or lower or an ultra-low melting glass having a softening temperature of about 400 ° C. or lower.
The optical element 1 is formed in a circular shape when viewed from the optical axis direction. In the optical element 1, a lens portion 1a having an optical functional surface is formed at the center, and an edge portion 1b for protecting the lens portion 1a is formed on the outer periphery thereof. Further, in the optical element 1, a peripheral edge portion 1c that enters a concave portion 2a (described later) formed on the inner peripheral surface of the lens barrel 2 is formed on the outer periphery of the edge portion 1b.

Here, the lens portion 1a is formed in a spherical shape or an aspherical shape, and refracts incident light at a predetermined refraction angle and emits it from an exit surface opposite to the entrance surface.
The edge portion 1b is formed with a predetermined thickness c around the lens portion 1a and functions to hold the lens portion 1a. The edge portion 1b does not have an optical function such as refraction of incident light.
When the glass preform 14 (see FIG. 2), which will be described later, is press-molded, the peripheral portion 1c is formed by entering the recess 2a formed on the inner peripheral surface of the lens barrel 2 (described later). Fix to the tube 2. In the following description, the supplied glass preform 14 (see FIG. 2) may be referred to as a surplus portion including a portion that does not completely enter the recess 2a.

For the lens barrel 2, a material having a larger linear expansion coefficient than the material of the optical element 1 is preferably selected, and is made of, for example, stainless steel or Kovar. When the thermal expansion coefficient of the lens barrel 2 is larger than the thermal expansion coefficient of the optical element 1, the lens barrel 2 contracts more than the optical element 1 during cooling, and the lens barrel 2 tightens the optical element 1. Bonding strength (attachment strength) with the optical element 1 is increased.
The lens barrel 2 has a cylindrical shape with an inner diameter d. The lens barrel 2 has a function of protecting the optical element 1, and the height of the lens barrel 2 is larger than the thickest portion of the lens portion 1 a of the optical element 1.
A concave portion 2 a having a width a and a depth b is formed in an annular shape on the inner peripheral surface of the lens barrel 2. A glass preform 14 (see FIG. 2) as an example of an optical material supplied at the time of press molding enters the recess 2a, and holds and fixes the optical element 1 to the lens barrel 2.

Here, the edge portion 1b overlaps a part of the recess 2a of the lens barrel 2 in the optical axis direction and does not overlap the other portion. That is, one surface (upper surface in FIG. 1) of the edge portion 1b is inside the recess 2a of the lens barrel 2 in the optical axis direction of the optical element 1, and the other surface (lower surface in FIG. 1) is outside the recess 2a. It is in. In other words, in the present embodiment, the center of the concave portion 2a of the lens barrel 2 in the optical axis direction does not coincide with the center of the thickness c of the edge portion 1b.
Further, the width a of the concave portion 2 a of the lens barrel 2 has a relationship of a> c with the thickness c of the edge portion 1 b of the optical element 1. When the width a of the concave portion 2a of the lens barrel 2 is smaller than the thickness c of the edge portion 1b of the optical element 1, the glass preform 14 covers the entrance of the concave portion 2a during press molding, and an air pocket is formed in the concave portion 2a. This is because the catching distance between the optical element 1 and the lens barrel 2 is not sufficiently secured.

The lens molding apparatus 10 for molding the holder optical element 5 having the above configuration will be described below.
2 and 3 are configuration diagrams of a lens molding apparatus 10 as an example of a glass optical element manufacturing apparatus for press molding the holder optical element 5 shown in FIG. FIG. 2 is a diagram showing a state in which a glass preform 14 as an example of an optical material is press-molded, and FIG. 3 is a diagram showing a state in which the holder optical element 5 is molded in the lens molding apparatus 10. .
As shown in FIG. 2, in the lens molding apparatus 10, a molding die (a fixed die 11 and a movable die 12) as an example of an optical element molding die according to the present embodiment is mounted. ing.

The lens molding apparatus 10 includes a fixed mold 11 disposed on the lower side and a movable mold 12 disposed on the fixed mold 11 so as to face the fixed mold 11. The movable mold 12 moves up and down by a driving mechanism (not shown). The lens molding apparatus 10 includes a barrel mold 13 that positions the lens barrel 2 at a predetermined position and regulates the operation of the movable mold 12.
The fixed mold 11 and the movable mold 12 include, for example, a cemented carbide containing tungsten carbide (WC) as a main component. In the fixed mold 11 and the movable mold 12, a coating layer (not shown) is formed on the molding surfaces (lens molding surfaces 11a and 12a and edge molding surfaces 11b and 12b described later) in order to realize a suitable mold release. Has been. The coating layer is formed of, for example, a platinum (Pt) -iridium (Ir) alloy. Note that the fixed mold 11 and the movable mold 12 may be made of a base material made of a material having both high temperature durability and strength, such as silicon carbide and glassy carbon. Further, cermet, inconel, stabux, high speed steel, die steel, or the like may be properly used depending on the yield point (deflection temperature) At of the glass material. The coating layer has low reactivity with fluorine and chlorine such as noble metal alloys other than platinum-iridium alloys, alloys of noble metals and transition metals, alloys of noble metals and general purpose metals, carbon, or DLC (diamond-like carbon). Any material is preferably used.

Each of the fixed mold 11 and the movable mold 12 has a lens portion molding surface 11a as an example of an optical function surface molding surface for molding the lens portion 1a (see FIG. 1) of the optical element 1 at the center of the molding surface. 12a is formed. Then, on the outer periphery of the lens part molding surfaces 11a and 12a, edge part molding surfaces 11b and 12b for molding the edge part 1b (see FIG. 1) of the optical element 1 are formed.
The fixed mold 11 and the movable mold 12 are press-molded with their molding surfaces (11a, 11b and 12a, 12b) facing each other in the cylinder of the lens barrel 2.

The movable mold 12 is formed with a predetermined amount of chamfer 12c as an example of a relief portion at the corner of the edge portion molding surface 12b, and absorbs excess glass preform 14 between the inner peripheral surface of the lens barrel 2 and the movable die 12. A void is formed.
For example, the body mold 13 includes a cemented carbide containing tungsten carbide as a main component. The body mold 13 regulates the operation of the movable mold 12 that moves up and down using a drive mechanism (not shown) so that the central axes of the fixed mold 11 and the movable mold 12 do not shift. The barrel mold 13 positions the lens barrel 2 at a predetermined position.

A manufacturing process in which the lens optical device 10 having the above configuration press-molds the glass preform 14 to manufacture the holder optical element 5 will be described below.
As shown in FIG. 3, in the lens molding apparatus 10, the lens barrel 2 is set on the fixed mold 11, and the barrel mold 13 is set on the outside thereof. A spherical glass preform 14 as an example of an optical material is placed on the lens portion molding surface 11 a of the fixed mold 11, and the movable mold 12 is fitted into the barrel mold 13. Opposed.
Here, the glass preform 14 is a material of the optical element 1 described above, and is, for example, a low-melting glass mainly composed of silica or an ultra-low melting glass.

Further, when the glass preform 14 placed on the fixed mold 11 has the volume f of the concave portion 2a of the lens barrel 2, the sum of the volumes of the lens portion 1a and the edge portion 1b is calculated from the total volume of the glass preform 14. The volume e of the surplus part obtained by subtracting is determined to have a relationship of 0.833 × f <e <1.25 × f.
If the volume e of the surplus portion is too small as compared with the volume f of the recess 2a, sufficient fitting cannot be performed and the mechanical strength is lowered. Therefore, a relationship of 0.8 × e <f is preferable. Further, if the volume e of the surplus portion is too large compared to the volume f of the concave portion 2a, the surplus portion may cover the effective optical surface (lens portion), so the relationship of f <1.2 × e is preferable. That is, a relationship of 0.8 × e <f <1.2 × e is preferable. If this inequality is expressed on the basis of the volume e of the surplus portion of the glass preform 14 to be placed, it is expressed by a relationship of 0.833 × f <e <1.25 × f. The volume f of the concave portion 2a of the lens barrel 2 is expressed by the following equation, where d is the inner diameter of the lens barrel 2.

The air inside the lens molding apparatus 10 is replaced with nitrogen gas using an exhaust pump and a processing gas introduction pump (not shown). Then, the glass preform 14 is sufficiently heated to a transition point (transition temperature) Tg of the glass preform 14 in a nitrogen atmosphere by a temperature raising mechanism (not shown), and further heated to a yield point (deflection temperature) At to increase the glass temperature. The preform 14 is softened.
When the temperature reaches the yielding temperature At, the movable mold 12 is pressed by a driving mechanism (not shown) to press-mold the glass preform 14. The glass preform 14 forms the lens portion 1 a and the edge portion 1 b and also forms a peripheral edge portion 1 c that enters the recess 2 a formed on the inner peripheral surface of the lens barrel 2, and fixes the optical element 1 to the lens barrel 2. At this time, a part (excess part) of the glass preform 14 is accommodated in a gap formed between the inner peripheral surface of the lens barrel 2 and the chamfer 12 c of the movable mold 12.
Thereafter, the lens molding apparatus 10 is cooled to the transition temperature Tg while pressure is applied, and the pressure of the movable mold 12 is released to cool to room temperature, and the holder optical element 5 is taken out (see FIG. 3).

According to the present embodiment, there is a relationship of a> c between the width a of the concave portion 2 a of the lens barrel 2 and the thickness c of the edge portion 1 b of the optical element 1. Therefore, since the glass preform 14 pushed by the movable mold 12 can enter the recess 2a, a sufficient distance between the optical element 1 and the lens barrel 2 is secured. Therefore, the mounting strength can be ensured, and the airtightness of the upper and lower spaces can be ensured with the optical element 1 interposed therebetween.
According to the present embodiment, one surface (upper surface in FIG. 1) of the edge portion 1b is inside the recess 2a of the lens barrel 2 in the optical axis direction of the optical element 1, and the other surface (lower surface in FIG. 1). ) Is outside the recess 2a. Therefore, the glass preform 14 pushed by the movable mold 12 enters from one side (the lower side in FIG. 1) of the concave portion 2a formed in the lens barrel 2, and other air accumulated in the concave portion 2a Extrude to the side (upper side in FIG. 1) in order. Thereby, it is difficult to form an air pocket in the recess 2a formed in the lens barrel 2, and as a result, a catching distance between the optical element 1 and the lens barrel 2 is ensured, and a mounting strength can be ensured.

According to the present embodiment, the volume e of the surplus portion of the glass preform 14 placed on the fixed mold 11 is 0.833 × f <e <with respect to the volume f of the recess 2 a of the lens barrel 2. It has a relationship of 1.25 × f. Therefore, the catch distance between the optical element 1 and the lens barrel 2 is ensured without excess or deficiency in the placed glass preform 14, and the mounting strength can be ensured.
According to the present embodiment, the movable mold 12 has a predetermined amount of chamfer 12c formed at the corner of the edge forming surface 12b, and an excess glass preform 14 between the inner peripheral surface of the lens barrel 2 and the movable die 12. The void | hole which absorbs is formed. Therefore, even if the glass preform 14 placed on the fixed mold 11 enters the recess 2a of the lens barrel 2 and extrudes the air after extruding from the recess 2a, the press molding of the optical element 1 is not hindered.

In the above embodiment, the cylindrical barrel 2 has been described as an example, but the present invention is not limited to this. For example, the present invention can be applied to a rectangular tube-shaped lens barrel.
Moreover, although the recessed part 2a formed in the lens-barrel 2 demonstrated as an example the annular recessed part 2a formed in the inner peripheral surface whole periphery of the lens-barrel 2, this invention is not limited to this. For example, it may be formed on a part of the inner peripheral surface. If the average width a of the recess 2a has a relationship of a> c with respect to the thickness c of the edge portion 1b, the effect of the present invention can be achieved.
Furthermore, the present invention can be applied to a Fresnel lens.

It is sectional drawing of the holder optical element concerning this Embodiment. It is a block diagram (the 1) of the lens shaping | molding apparatus which press-molds the holder optical element shown in FIG. FIG. 3 is a configuration diagram (No. 2) of a lens molding apparatus for press molding the holder optical element shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical element (lens main body), 1a ... Lens part, 1b ... Edge part, 1c ... Peripheral part, 2 ... Lens barrel, 2a ... Concave part, 5 ... Holder optical element (optical element with a lens barrel), 10 ... Lens molding Apparatus (glass optical element manufacturing apparatus), 11 ... Fixed mold (optical element molding mold), 12 ... Movable mold (optical element molding mold), 13 ... Body mold, 11a, 12a ... Lens part molding surface (Optical function surface molding surface), 11b, 12b ... Edge molding surface, 12c ... Chamfer (relief part), 14 ... Glass preform (optical material)

Claims (6)

A lens barrel having a cylindrical shape and having a recess formed on the inner surface of the cylindrical shape;
A lens body held by the lens barrel, and
The lens body is
A lens portion having an optical functional surface;
An edge portion formed on an outer periphery of the lens portion and abutted against the lens barrel;
A peripheral portion that is formed on the outer periphery of the edge portion and holds the lens body by entering the concave portion of the lens barrel;
The concave portion of the lens barrel has a relationship in which the width a of the concave portion in the optical axis direction of the lens body satisfies a> c with respect to the thickness c of the edge portion of the lens body. Optical element with cylinder.   In the edge portion of the lens body, any one surface of the edge portion is inside the concave portion of the lens barrel in the optical axis direction, and the other surface of the edge portion is the optical axis direction of the concave portion. The optical element with a lens barrel according to claim 1, wherein the optical element is on the outer side of the lens. When the volume f of the concave portion of the lens barrel is set,
The optical material supplied for press molding of the optical element has a volume e obtained by subtracting the sum of the volumes of the lens body and the edge portion from the total volume of the optical material.
0.833 × f <e <1.25 × f
The optical element with a lens barrel according to claim 1, wherein: A lens barrel having a cylindrical shape and having recesses formed on the entire circumference of the cylindrical inner surface;
A lens body held by the lens barrel, and
The lens body is
A lens portion having an optical functional surface;
An edge portion formed on an outer periphery of the lens portion and abutted against the lens barrel;
A peripheral portion that is formed on the outer periphery of the edge portion and holds the lens body by entering the concave portion of the lens barrel;
The edge part of the lens body overlaps with a part of the recess of the lens barrel in the optical axis direction of the lens body and does not overlap with the other part. An optical functional surface molding surface that molds the optical functional surface of the lens body included in the optical element with the lens barrel, and an edge portion molding surface that is formed on the outer periphery of the optical functional surface molding surface and molds the edge portion of the lens body. It has a pair of fixed mold and movable mold,
The fixed mold and the movable mold are arranged to face each other inside the lens barrel having a cylindrical shape that the optical element with the lens barrel has a recess formed on the entire inner surface.
The fixed mold and the movable mold press the optical material, and a part of the pressed optical material enters the concave portion of the lens barrel and presses the lens body held and fixed to the lens barrel. In the optical element molding die to be molded,
The mold for molding an optical element, wherein the movable mold that slides in the lens barrel has a relief portion that absorbs excess optical material at a position corresponding to the concave portion of the lens barrel. . The edge molding surface of the fixed mold is disposed outside the concave portion of the lens barrel in the optical axis direction of the lens body,
6. The optical element according to claim 5, wherein the edge forming surface of the movable mold slides to the inside of the concave portion of the lens barrel in the optical axis direction to press-mold the optical material. Mold for molding.

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