TWI437304B - Optical lens unit and plastic lens forming mold and plastic lens manufacturing method therefor - Google Patents

Description

Optical lens element and manufacturing method of plastic lens molding die and plastic lens

The present invention relates to an optical lens element for use in an optical lens and a conventional zoom lens for a portable telephone and a palmtop terminal, and a digital camera, and the optical lens element capable of positioning the optical lens and the lens barrel with high precision and the plastic lens molding die. And a method of manufacturing a plastic lens.

In recent years, with the expansion of the portable terminal market equipped with an imaging device, it has become a trend to mount a solid image sensor having a small picture element in an imaging device. In accordance with the miniaturization and high image formation of the image pickup device, for example, as disclosed in Patent Documents 1 and 2, an image pickup lens composed of a plurality of lenses is gradually being popularized.

The image pickup lens shown in Patent Document 1 has a configuration in which one plastic lens and one glass lens are provided, and a lens barrel in which the lenses are incorporated, so that the peripheral region of the lens in contact with the plastic lens and the glass lens has the same curvature. Or the same taper surface, when the lens is placed in the frame, the contact lens of the plastic lens first loaded into the frame and the receiving surface of the lens barrel are abutted, and the lens barrel and the plastic lens are positioned to make the glass lens and the mirror While the inner peripheral surface of the cylinder is fitted, the plastic lens is clamped by the receiving surface of the lens barrel and the glass lens by pressurizing the plastic lens in the optical axis direction, and the same curvature or the same inclination is formed in the peripheral region of each lens. The fitting of the tapered faces makes the optical axes of the lenses coincide.

Further, in Patent Document 2, a proposal has been made in which a lens incorporated in a lens barrel is an image pickup lens composed of a plastic lens, and is used for an image pickup lens of an ordinary portable telephone or the like, and a lens incorporated in the lens barrel. All of them are composed of a plastic lens which is easy to be molded, and in a digital camera or the like, a zoom lens is used as a main stream, and a lens incorporated in the lens barrel is composed only of a glass lens, or is generally a glass lens as described in Patent Document 1. A combination of plastic lenses. In Patent Document 1 and Patent Document 2 As shown in FIG. 3 and FIG. 4, the illustrated imaging lens is formed such that the outer diameter of the plastic lens is slightly smaller than the inner diameter of the lens barrel, and the radial gap between the lens barrel and the lens barrel is maintained and inserted into the lens barrel to The direction of the optical axis presses the state of the lens inserted into the lens barrel, and the last lens is fixed by an adhesive or by a lens presser pressed into the lens barrel.

Previous technical literature

Patent Document 1: Japanese Patent Publication No. 9-113783

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-338869.

As shown in FIG. 3, for example, as shown in FIG. 3, the imaging lens of the first plastic lens R1 inserted first into the lens barrel K and the lens U formed on the lens barrel K are formed as shown in FIG. When the abutting surface K1 abuts, the receiving surface U and the abutting surface K1 are perpendicular to the optical axis, and the first plastic lens R1 is positioned in the optical axis direction with respect to the lens barrel K. In this state, the next segment is sequentially 2 plastic lens R2 (glass lens in Patent Document 1) is inserted, and the conical surface T formed on the overlapping surface of the edge portions R1a and R2a of the respective lenses R1 and R2 is fitted (or engaged) with each other. When the optical axes of the lenses R1 and R2 match each other, the final lens is fixed to the inner circumferential surface of the lens barrel K with an adhesive or the like.

However, the above-described elementized lens groups R1, R2 disposed in the lens barrel K are formed such that the outer diameters of the respective lenses R1, R2 are smaller than the inner diameter of the lens barrel K, and thus form a fine relationship with the lens barrel K. The gap is obtained by abutting the receiving surface U of the first inserted plastic lens R1 and the abutting surface K1 of the lens barrel K, and positioning all of the componentized plastic lenses R1, R2 with respect to the lens barrel K, and The receiving surface U of the plastic lens R1 and the abutting surface K1 of the lens barrel K are perpendicular to the optical axis. Due to the radial gap between the plastic lenses R1, R2 and the lens barrel K, the plastic lenses R1, R2 can follow the diameter. The movement has a problem that the positioning accuracy of each of the plastic lenses R1, R2 with respect to the lens barrel K is lowered.

As a method of preventing a decrease in the positioning accuracy caused by the radial gap between the respective plastic lenses R1, R2 and the lens barrel K, it is considered that the plastic lens R1 and the lens barrel K which are first inserted into the lens barrel K are positioned in the radial direction. For example, the first inserted plastic lens R1 and the lens barrel K have the same concentric structure as the respective plastic lenses R1, R2. That is, as shown in FIG. 4, on the receiving surface U of the plastic lens R1, a conical conical surface T1 and a conical receiving surface T2 are respectively formed on the abutting surface K1 of the lens barrel K, and if these conical surfaces T1 and conical receiving surfaces are made T2 is respectively fitted (or engaged), and the concentric structure of each plastic lens R1, R2 is the same, and the lens barrel K and the plastic lens R1 can be positioned in the radial direction, and the lens barrel K and the plastic lens R1 are concentric. As described above, when the plastic lens R1 which is concentrically positioned with respect to the lens barrel K is used as a reference, the next second plastic lens R2 is superposed in order, and the conical surfaces T formed on the respective lenses R1 and R2 are fitted to each other. Then, the plurality of plastic lenses R1, R2 in the lens barrel K can be positioned with high precision.

However, the plastic lens R used in such an optical lens is molded by injection molding by a molding die. The general structure of such a plastic lens molding die will be described with reference to Fig. 5. The plastic lens molding die is formed by a fixed mold 100 and a movable mold 101. The most important lens portion R ' in the optical lens is used in each of the molds 100, 101. The detachably mounted mold inserts 100A, 101A are formed, and the edge portion Ra of the plastic lens R including the conical surface Ta located on the outer circumference of the lens portion R ' is formed by the fixed mold 100 and the movable mold 101. That is, the fixed mold 100 and the movable mold 101 collide with the two molds 100, 101 at the time of mold clamping, and thus are formed of a material having high rigidity, and on the other hand, the mold inserts 100A, 101A and the lens surface of the lens portion R ' are formed. The surface of the mold inserts 100A, 101A is subjected to a cutting process by coating with a Ni plating layer, and the mold 100 is fixed from the structure. The movable mold 101 and the mold inserts 100A, 101A are formed by different members, and then the mold insert 100A is to be formed. 101A is assembled with respect to the fixed mold 100 and the movable mold 101. For assembly, a fixed gap is required between the fixed mold 100, the movable mold 101, and the mold inserts 100A, 101A. Due to the gap, the conical surface Ta formed by the movable mold 101 and the mold insert 100A, 101A are formed by the fixed mold 100. Between the formed lens portions R ' , a radial offset due to a gap when the mold inserts 100A, 101A are placed may occur. That is, a molding error called offset is generated in the radial direction of the conical surface Ta and the lens portion R ' . As a result, the positioning accuracy of the lens portion R ' fitted to the conical receiving surface T2 of the lens barrel K is lowered.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical lens element and a plastic lens forming mold and a plastic lens which can position the optical axis of the lens barrel and the optical lens with high precision, and can form the optical lens with high precision. Manufacturing method.

In order to achieve the above object, the technical solution adopted by the present invention is as follows: an optical lens element having a cylindrical lens barrel having an opening at each end and a plastic lens disposed in the lens barrel; the plastic lens having the same An edge portion on the outer circumference and a lens portion having a conical surface on the outer circumference of the edge portion, the inner circumferential surface of the lens barrel being a vertical surface abutting the conical surface in a line contact state. When the plastic lens is loaded into the lens barrel, the conical surface of the outer circumference of the edge portion of the plastic lens abuts the vertical inner circumferential surface of the lens barrel in a line contact state, so that the lens barrel and the plastic lens Precise positioning in a concentric manner.

A plurality of plastic lenses are housed in the lens barrel, and conical surfaces that can be engaged with each other are formed on the surfaces of the plastic lenses that overlap each other.

The conical surface formed on the edge portion of the outer circumference of the plastic lens first inserted into the lens barrel abuts against the vertical inner circumferential surface of the lens barrel in a line contact state, so that the lens barrel and the plastic lens are concentric. Inserting the plastic lens of the next segment sequentially in a state in which the lens barrel and the plastic lens are concentrically positioned, by the overlapping surfaces of the plastic lenses The formed conical surfaces are engaged, and the optical axes of all the plastic lenses accommodated in the lens barrel can be made uniform with respect to the plastic lens positioned with respect to the lens barrel.

In addition, the present invention further includes a plastic lens molding die comprising a fixed mold, a movable mold that can be opened and closed with respect to the fixed mold, and a mold insert that can be assembled with the fixed mold and the movable mold, wherein the mold A block is formed to form the lens portion and the conical surface.

Since the lens portion and the conical surface of the plastic lens are integrally formed by the mold insert, there is no gap between the lens portion and the conical surface due to a gap between the mold insert and the movable mold and the fixed mold. The offset is generated so that the dimensional accuracy of the lens portion and the conical surface is kept high, so that the optical axis of the lens barrel and the optical axis of the plastic lens can be accurately aligned.

The present invention further includes a method of manufacturing a plastic lens, which is filled with a resin into a cavity surrounded by the fixed mold, the movable mold, and the mold insert, and the plastic lens is injection molded. .

According to the method for manufacturing a plastic lens described above, it is possible to manufacture a plastic lens that maintains the dimensional accuracy of the lens portion and the conical surface with high precision at a low cost and in a large amount, and the manufacturing cost of the plastic lens can be reduced.

According to the present invention, the lens portion and the conical surface of the plastic lens are molded by the mold of the molding die, and the lens portion can be always maintained with high precision. And the dimensional accuracy of the conical surface, when the plastic lens is loaded into the lens barrel, the conical surface of the plastic lens and the inner circumferential surface of the lens barrel are fitted, so that the lens barrel and the plastic lens are concentric The way to position accurately.

In addition, the outer circumference of the plastic lens that is first inserted into the lens barrel is formed on the edge portion The conical surface abuts against the vertical inner circumferential surface of the lens barrel in a line contact state, and the lens barrel and the plastic lens are sequentially inserted into the plastic lens of the next segment in a state of being concentrically positioned, and the plastic lenses are overlapped by the plastic lenses. The conical surfaces formed on the surface are engaged with each other, and the optical axis of all the plastic lenses accommodated in the lens barrel can be made uniform with respect to the plastic lens positioned with respect to the lens barrel.

The invention will be further described below in conjunction with the drawings and embodiments.

1 is a cross-sectional view showing an optical lens according to Embodiment 1 of the present invention, and an embodiment shown in FIG. 1 is omitted from the prior art shown in FIG. 3 and FIG. For the repeated parts of the example, only the different parts are labeled.

As shown in FIG. 1 , the present invention comprises a plastic lens 1 and a lens barrel K for accommodating the plastic lens 1 . The plastic lens 1 comprises a lens portion 2 and a lens extending from a peripheral portion of the lens portion 2 in a circumferential direction. The edge portion 3 is composed. A conical surface 15 and 5 are formed on the outer circumference and the upper side of the edge portion 3, respectively. The conical surface 15 formed on the outer circumferential surface of the edge portion 3 is formed in a conical shape that is inclined in a direction approaching the optical axis from the top to the bottom. The lens barrel K has a vertical inner circumferential surface. When the plastic lens 1 is loaded into the lens barrel K, the upper edge of the conical surface 15 of the outer circumference of the edge portion 3 of the plastic lens 1 is in line contact state. The vertical inner circumferential surface of the lens barrel K is attached so that the lens barrel K and the plastic lens 1 are concentric. Referring to FIG. 4, when a plurality of plastic lenses 1 and R2 are mounted in the lens barrel K, the conical surface 5 formed on the upper edge of the plastic lens 1 is fitted to a conical surface T of the second plastic lens R2. The optical axis of the lens barrel K is made to coincide with the optical axis of each of the plastic lenses R1 and R2 with high precision. As shown in FIG. 2, a molding die 20 for manufacturing the plastic lens 1 is composed of a fixed mold 21, a movable mold 22, and mounted on the fixed mold 21 and the movable mold 22. The upper and lower pair of two mold inserts 23, 24 are composed. The fixed mold 21 and the movable mold 22 are moved up and down along the optical axis direction of the plastic lens 1 to perform an opening and closing operation, and the fixed mold 21 is clamped with the movable mold 22 to the fixed mold 21 and the movable mold 22 The cavity surrounded by the two mold inserts 23 and 24 is filled with a molten resin, and the plastic lens 1 is injection molded. In addition, the lens upper surface of the lens portion 2 of the plastic lens 1 and the conical surface 5 are integrally formed by the mold insert 23, and the lower surface of the lens portion of the lens portion 2 and the conical surface 15 of the plastic lens 1 are borrowed. The mold insert 24 is integrally formed.

That is, in the molding die 20 of the plastic lens 1 according to the present invention, the upper surface of the lens of the lens portion 2 and the conical surface 5 of the plastic lens 1 which determine the optical performance of the plastic lens 1 are mounted on the movable mold 20 The mold insert 23 of the mold 22 is integrally formed, and the lower surface of the lens of the lens portion 2 and the conical surface 15 of the plastic lens 1 are integrally molded by the mold insert 24 mounted on the fixed mold 21. As shown in FIG. 5, taking the prior art mentioned above as an example, it is expected that the conical surfaces 15, 5 and the gap between the fixed mold 21, the movable mold 22, and the mold inserts 23, 24 may be caused by the gap. The lens portion 2 generates a molding error called offset in the radial direction. On the other hand, according to the molding die structure of the present invention, the lens surface of the plastic lens 1 on the movable mold 22 side and the conical surface 5 side, and the lens surface on the side of the fixed mold 20 and the conical surface 15 are integrated. forming. Therefore, the positional accuracy of the conical surfaces 15, 5 and the lens portion 2 can be improved. In addition, the mold inserts 23 and 24 can be detachably attached to the fixed mold 21 and the movable mold 22, and the shrinkage ratio of the lens portion 2 formed by the mold inserts 23 and 24 does not conform to the design value after molding. Since the shape of the mold inserts 23 and 24 is relatively easy to change, it is relatively easy to modify or process the surface shape of the lens portion 2 after molding, and to modify and process the diameter of the conical surface. Close to the design value.

In the present embodiment having the above configuration, the lens portion 2 and the conical surfaces 15 and 5 connected to the lens portion 2 are molded by the mold inserts 23 and 24, whereby the lens portion 2 and the conical surface 15 can be formed. 5 becomes a concentric state and is consistent with high precision. As described above, by ensuring the molding accuracy of the conical surfaces 15, 5, when the plastic lens 1 is loaded into the lens barrel K, the conical surface 15 formed on the outer circumference of the plastic lens 1 is in line contact with the mirror. The inner circumferential surface of the cylinder K is perpendicular, so that the lens barrel K and the plastic lens 1 can be accurately positioned concentrically. Further, by using the plastic lens 1 provided on the lens barrel K as a reference, by fitting the conical surface of the plastic lens of the next stage to the conical surface 5 of the plastic lens 1 in turn, when the lens barrel K is loaded In the case of the plastic lenses 1 and R2, the components can be placed in the lens barrel K in a state in which the optical axes between the lenses are unified.

Further, the lens portion 2 forming the plastic lens 1 and the mold inserts 23 and 24 of the conical surfaces 15 and 5 can be detachably attached to the fixed mold 21 and the movable mold 22, and the mold insert 23 is changed. When the aspherical shape of 24 is 24, the repair processing can be easily performed, and the surface shape of the lens portion 2 can be made closer to the design value.

Further, in the present embodiment, since the shape of the lens barrel K can be simply molded by vertically forming the inner circumferential surface, the molding process of the lens barrel K is also easy. The embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described above, and various modifications may be made without departing from the spirit and scope of the invention. For example, the shape of each lens and the shape of a conical surface that coincides with the optical axis of each lens, and the number of lenses incorporated in the lens barrel may be one, or may be appropriate for different instruments incorporating the optical lens. Select the number of lenses loaded into the lens barrel. Further, the mold structure of the molding die for molding the optical lens is not limited to the above embodiment, and can be appropriately selected.

1, R, R1, R2‧‧‧ plastic lens

2‧‧‧R’ lens section

3. R1a, R2a, Ra‧‧‧ edge parts

5, 15, T, T1, Ta‧‧ ‧ conical surface

20‧‧‧Molding mould

21, 100‧‧‧ fixed mold

22, 101‧‧‧ movable mold

23, 24, 100A, 101A‧‧‧ mold inserts

K‧‧·ray tube

K1‧‧‧ Abutment

T2‧‧‧cone bearing surface

U‧‧‧ receiving surface

Figure 1 is a cross-sectional view of an embodiment optical lens; 2 is a cross-sectional view showing a molding die for a plastic lens according to an embodiment; FIG. 3 is a cross-sectional view showing a conventional optical lens; FIG. 4 is a cross-sectional view showing a modified structure of a lens barrel and a plastic lens; FIG. A cross-sectional view of the forming mold.

1‧‧‧ plastic lens

2‧‧‧Lens Department

3‧‧‧Edge

5, 15‧‧‧ Conical surface

K‧‧·ray tube

Claims (4)

An optical lens element, characterized in that: the optical lens element has a cylindrical lens barrel having an opening at each end thereof; a plastic lens disposed in the lens barrel; the plastic lens having an outer circumference An edge portion and a lens portion having a conical surface on the outer circumference of the edge portion, the inner circumferential surface of the lens barrel being a vertical surface abutting the conical surface in a line contact state. The optical lens element according to claim 1, wherein a plurality of plastic lenses are housed in the lens barrel, and a conical surface that can be engaged with each other is formed on each of the overlapping surfaces of the plastic lenses. A plastic lens forming mold for forming the plastic lens according to claim 1, wherein the plastic lens molding die comprises a fixed mold; a movable mold that can be opened and closed with respect to the fixed mold, and A mold insert that can be assembled with the fixed mold and the movable mold, wherein the mold insert forms the lens portion and the conical surface. A plastic lens forming mold according to the third aspect of the invention, characterized in that the cavity enclosed by the fixed mold, the movable mold and the mold insert is filled with a resin. The plastic lens is injection molded.