JPS61261015A - Plastic lens and its mold - Google Patents

Abstract

PURPOSE:To prevent deterioration in optical performance also by omitting burr treatment after molding, by so constituting the title mold that the crest line part between the external circumferential surface of the brim part of a lens and both side planes is notched and a parting line between a stationary mold and movable mold in the mold are not provided on the external circumfer ential surface of the brim part. CONSTITUTION:As for a mold, it is so constituted that a stationary insertion piece 2 and movable insertion piece 4 are united respectively with a stationary rest 1 and movable rest 3, and a parting line 11 between a stationary mold and movable mold is flush with a plane 7 of the brim part 6. A plastic lens obtained by nothing the crest line part between both side planes 7 of the brim part 6 and the circumferential surface 8 is molded by filling a cavity formed of the stationary insertion piece 2 and movable insertion piece 4 with polymethyl methacrylate. Although longitudinal burrs 14 are generated on the fringe part of the circumferential surface of the brim part 6, as the burrs 14 do not abut against an interval annulus 13 when the lens is incorporated into a lens tube 12, it does not happen that eccentricity and slant are generated on the lens.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a plastic lens and a mold for molding the same. The present invention relates to a plastic lens and a mold for molding the same.

First, general injection compression molding molds for molding plastic lenses will be explained.

FIG. 8 is a vertical cross-sectional view showing an example of this injection compression mold. In FIG.
1 is a nozzle and a runner for guiding the resin (not shown) injected from this nozzle portion to the cavity 25 ◇ 22 is a gate portion, and 2 and 4 are for forming a lens surface. The fixed insert pieces and movable insert pieces 15 and 16, which have surfaces and form the cavity 23, connect the fixed insert pieces 2 and the movable insert pieces 4 to the fixed mold 24 and the movable mold 25.
A fixed sleeve and a movable sleeve are supported within.

26 is a cylinder for applying pressure to the movable input piece 4 via the extrusion plate 27 and the pressure block 51t, and also for pushing out the resin (molded product) in the cavity; 2B is a hydraulic bong for supplying hydraulic pressure to the cylinder 26; be.

29 and 30 are a fixed mounting plate and a movable mounting plate for mounting this mold on a molding machine.

Next, the operation of the injection compression mold constructed as described above will be explained. After the molded product is taken out from the cavity 25, the fixed mold 24 and the movable mold 25 are closed to enable molding into the mold, and the molding machine nozzle part (not shown) hits the nozzle R contact $19. Resin comes into contact with the mold from the nozzle (not shown)
is ejected.

The resin passes through the nozzle 20 and the runner 21 to the cavity 26.
Filled with. After a certain period of time after the filling is completed, a signal (not shown) is sent from the injection molding machine to the hydraulic pressure button 28. As a result, the hydraulic cylinder 128 is operated and hydraulic pressure is supplied to the hydraulic cylinder 26.

The hydraulic cylinder 26 that receives this oil pressure applies compressive force to the resin in the cavity 25 through the extrusion plate 27, the pressure block 51, and the movable input piece 4''Ik, and performs compression molding of the resin in the cavity 25. After the molded product in 26 has cooled down, the molding machine moves to the mold opening operation.That is, the movable mold 25 is moved to the left in the figure by a W opening mechanism (not shown), and the fixed mold 24 and movable mold 25 are separated. There is a gap and I lie.

In this case, the molded product inside the cavity 23 is the movable sleeve 1
◇ Therefore, after the above-mentioned compression molding, the hydraulic cylinder 28, which had been temporarily stopped, should be activated again, and the hydraulic cylinder 26 should be moved to the right in the figure. The pressure block 31 and the movable inserting piece 4 are moved to the right. Son
As a result, the molded product that has adhered to the movable sleeve 16 and has moved is removed from the movable sleeve.

After the molded product has been removed, the fixed mold 24 and the movable mold 25 are closed again to make it ready for molding. Thereafter, by repeatedly performing the operations described above, molding is performed continuously.

FIG. 9 is a front view of a conventional flanged plastic lens molded using an injection compression mold having the above-mentioned configuration, and FIG. 10 is a side view thereof.

In FIGS. 9 and 10, 5 is a lens portion, 10 is a rotationally symmetrical axis of the lens s5, which is called the optical axis of the lens, and 6 is an axis of two planes 7 perpendicular to the optical axis 10, and the optical axis is the axis thereof. This is a collar portion formed by the circumferential surface 8.

In order to configure an optical system having the desired optical performance by combining two or more flange-shaped plastic lenses having the above shape, it is necessary to align the optical axes 10 of all the lenses with high precision,
In addition, it is essential to maintain the lens spacing with high precision.

Therefore, as shown in FIG. 11, a lens barrel 12 whose inner diameter is approximately equal to the lens diameter, an outer diameter which is approximately equal to the inner diameter of the lens barrel, and a thickness t of the end face perpendicular to the optical axis is the width of the lens brim 6. A plurality of lenses L1. The interval of L2 is
It is held by a spacing ring 13 built into the lens barrel 12 to form an optical system.

In this case, in order to make the optical axes 10t of each lens coincide, the outer circumferential surface of the collar 6 is in contact with the inner circumferential surface of the lens barrel 12, and at the same time
In order to maintain the lens spacing, the flat portion 7 of the flange surface 6 is in contact with the end surface of the spacing ring 13.

However, the flange portion 6 of the flanged plastic lens molded by the injection compression mold has vertical burrs 14, lateral burrs 18, etc. as shown in FIG. 12.

FIG. 16 is a sectional view of the main part of the molding die showing the state in which this burr is generated. The vertical burr 14 is located at the fitting part between the movable sleeve 16 and the movable insert piece 4, and the horizontal burr 18 is located at the fitting part between the movable sleeve 16 and the movable insert piece 4.
This occurs at the dividing surface 11 between the movable input piece 5 and the movable input piece 4. Said bar 1J
14 and 18 are caused by manufacturing errors in mold processing, clearances for inserting pieces into the frame, and clearances for sliding pieces to pressurize the molded product, etc. nru.

If a plurality of classic lenses with flanges are assembled into the lens barrel 12 without removing the burrs 1714.18'i, the lens assembly may be eccentric or tilted due to the burrs. Optical performance deteriorates significantly.

For this reason, up until now, burrs have been removed by cutting or the like as a pretreatment. However, in this deburring process, it is difficult to hold the lens during the cutting process, and the cutting dust generated during the deburring process adheres to the lens surface, so a cleaning process must also be incorporated into the lens manufacturing process. . Therefore, the mass production ability of plastic lenses, which is inherently superior to glass lenses, has been significantly hindered.

[Purpose of the invention]

The present invention was made in order to eliminate the above-mentioned drawbacks, and its purpose is to prevent deterioration of optical performance even if the plastic lens is assembled into a lens barrel without performing burr treatment after molding. Our objective is to provide a classic lens and a mold for molding it.

[Summary of the invention]

In order to achieve the above object, the present invention focuses on the fact that no problem occurs if the burrs are generated in a tube part that is not involved in determining the position of the plastic lens within the lens barrel, and The ridgeline between the outer circumferential surface of the lens buckle and both side planes is cut out into an arbitrary shape, and the dividing surface between the fixed mold and the movable mold in the molding mold is not provided on the outer peripheral surface of the brim of the plastic lens. It is characterized by the fact that it is made as follows.

[Embodiments of the invention]

The invention will now be described in detail with reference to one drawing. Figure 1 shows No. 15 of the mold for molding the 1-Ranuchitsu lens of the present invention. FIG.
Components that are the same as those in FIG.

In Fig. 1, 1 is a fixed type, and 3 is a movable type.The peripheral edges of the cavity forming surfaces of the fixed insert piece 2 and the movable insert piece 4 are provided with flat surfaces 7 on both sides of the collar portion 6 on the outer periphery of the lens, and a circumferential surface. Slope protrusions 2a and 4 for forming a notch 9 on the ridgeline with 8.
〇 Then, the fixed insert piece 2 and the movable insert piece 4 having the above configuration are respectively assembled to the fixed frame 1 and the movable frame 3, and the fixed type and the movable type are separated. The surface 11 is configured to be flush with the plane 7 of the collar portion 6. Therefore, when the cavity formed by the fixed insert piece 2 and the movable insert piece 4 is filled with polymethyl methacrylate as a plastic lens material and molded, the both side planes 7 and the circumferential surface 8 of the flange portion 6- A classic lens with the ridgeline cut out is molded.

In this case, the dimensions of each part of the flange 6 are, for example, the distance between the lens cap 5 and the circumferential surface is 3 mm, the thickness of the flange 6 is 3 mm,
The planar length of the collar portion 6 is 2 mm, the circumferential surface length of the collar portion 6 is 1 mm, and a
Vertical burrs 14 were formed at an angle of 0 to 20 μm. - FIG. 2 shows a state in which the classical lens molded as described above is assembled into the lens barrel 12 using the spacing ring 13, and the burr 14 does not come into contact with the spacing ring 13.

Therefore, the lens is free from eccentricity, inclination, etc., and desired optical performance can be obtained.

FIG. 3 is a sectional view of a main part showing a second embodiment of a molding die for molding a 7 lath nut lens of the present invention, in which the peripheral edge of the cavity forming surface of the fixed insert piece 2 and the movable insert piece 4 is Since the square protrusions 2b and 4b are provided, the ridgeline portion of the flange portion 6 of the plastic lens molded with the mold of this second embodiment is cut into a square shape.

FIG. 4 is a cross-sectional view of a main part showing a third embodiment of a molding die for molding a classic lens of the present invention. , arcuate projections 2C and 4C are provided. Therefore, the ridgeline portion of the flange portion 6 of the plastic lens molded with the mold of this second embodiment is cut out in an arc shape.

No. 2 above. When the classic lens molded according to the third embodiment is also assembled into the lens barrel 12 using the spacing ring 13 as shown in FIG. Optical performance can be obtained.

Further, in the first to third embodiments, the position of the dividing surface 11 between the fixed type and the movable type is the same plane as the plane 7 of the collar portion 6, but this need not be the same plane. 5
As shown in the figure, there is no problem with rt and Fi in the portions that are not continuous with the cavity surface forming the circumferential surface 8 of the collar portion 6, the tabs, and within the range indicated by A in the figure.

In each of the above embodiments, in order to ensure that the convex cavity surface portion of the fixed inserting piece, which forms a notch in the ridgeline portion of the collar portion, fits well with the convex cavity surface portion of the movable inserting piece during mold clamping, the eighth The pieces are directly inserted into the frame without using the sleeve as shown in the figure, and the molding process is carried out. However, it goes without saying that a sleeve may also be used.

FIG. 6 is a sectional view of a main part showing a molding die in which a sleeve is used to improve the sliding movement of the movable insert piece 4.
In FIG. 6, 15 is a fixed sleeve and 16 is a movable sleeve.

In this embodiment, the fitting between the inner circumference of the movable sleeve 16 and the convex cavity surface 2a of the fixed insert piece 2 is due to machining errors between the insert piece and the sleeve, the sleeve and the frame, and
Because it is expected that the thermal expansion difference during molding of the sleeve and frame may be hindered, a semi-conical shape shown in FIG. Irregular guide portions 17 and 181 are provided. FIG. 7 is a sectional view of a main part of a molding die in which the fixed sleeve 15 and the movable sleeve 16 form a cavity surface for molding the buckwheat portion 6. In the case of this embodiment as well, uneven guide portions 17 and 181 are provided on the dividing surface 19 of both sleeves 15 and 16.
- By providing this, a good fit can be achieved during mold clamping.

In the embodiments shown in FIGS. 6 and 7 above, the glass lens was explained using a glass lens in which the sloped notch described in FIG. , K as explained in FIG.

The wire portion may be cut out into a rectangular shape and an arc shape.Also, the dividing surface 11 between the fixed type and the movable type or the dividing surface 19 between the fixed sleeve 15 and the movable sleeve 16 is as shown in FIG. Range 1i! ! liA, the rim, and the circumferential surface 8f of the collar 6: No problem will occur with lrL as long as they are continuous with the cavity surface to be formed.

Further, although the above embodiments were explained using a biconvex lens as the plastic lens, lenses of other shapes,
The same applies to concave lenses, meniscus lenses, etc. The material of the plastic lens may also be a resin other than the above-mentioned polymethyl methacrylate, such as polycarbonate or polystyrene.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, burrs that occur during molding are prevented from being generated at locations involved in determining the position of the lens within the lens barrel.
Jt-It can be incorporated into the lens barrel without being removed, and optical performance can be ensured.

For this reason, it is not necessary in the manufacturing process of glass lenses.
It is possible to eliminate processes such as deburring and cleaning, thereby achieving the effect of improving mass productivity.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main part showing the first embodiment of a molding die for molding a glasstic lens of the present invention, and Fig. 2 is a cross-sectional view of a plastic lens molded with this mold, which is assembled into a lens barrel. 3 to 7 are sectional views of main parts showing other embodiments of a mold for molding a plastic lens of the present invention, and FIG. 8 is a sectional view of an injection compression mold. A longitudinal cross-sectional view showing an example, Fig. 9 is a front view of a conventional glass lens with flanges, Fig. 10 is a side view thereof, and Fig. 11 is a longitudinal cross-section of the plastic lens with flanges installed in a lens barrel. 12 is a sectional view of a plastic lens showing the state in which burrs are generated, and FIG. 13 is a sectional view of a main part of a conventional molding die. 2...Fixed insert piece, 4...Movable insert piece, 5...Lens part, 6... Buckle part consisting of both side planes 7 and circumferential surface 8,
2a to 2c, 4a to 4C...cavity surface protrusion,
9... Notch, 10... Optical axis, 11.19...
- Divided surface, 24...fixed type, 25...movable type. sai l sai 2 sai 3 sai 4 sai 5 sai 5 sai 7 sai) X8 sai 9I! r Off 0 turn//Figure

Claims (8)

[Claims] (1) In a plastic lens in which a flange consisting of both planes perpendicular to the optical axis and a circumferential surface with the optical axis as the central axis is integrally molded on the outer periphery, a phenomenon occurs at the edge of the circumferential surface during molding. A plastic lens characterized in that a notch is provided at a ridgeline between the both side planes and the circumferential surface so that burrs do not protrude beyond a surface obtained by extending the both side planes. (2) The plastic lens according to claim (1), wherein the cutout portion has a sloped shape. (3) The plastic lens according to claim (1), wherein the cutout portion has a square shape. (4) The plastic lens according to claim (1), wherein the cutout portion is arcuate. (5) Consisting of at least a fixed type and a movable lid, and a fixed piece and a movable piece that are fitted into each of these two types and have a protrusion on the peripheral edge of the cavity forming surface, A mold for molding a plastic lens, characterized in that the mold is assembled so that the dividing surface is not continuous with the cavity surface forming the circumferential surface of the plastic lens. (6) A fixed sleeve is fitted into the fixed insert piece and a movable sleeve is fitted into the movable insert piece, and the molding is performed so that the dividing surfaces of both sleeves are not continuous with the cavity surface forming the circumferential surface of the plastic lens. Claim No. (5)
A mold for molding the plastic lens described in Section 1. (7) The mold for molding a plastic lens as set forth in claim (6), wherein the fixed sleeve and the movable sleeve are provided with a cavity forming surface for molding a flange portion of the plastic lens. (8) A mold for molding a plastic lens as set forth in claim (6), characterized in that a concave-convex guide portion for engagement is provided relative to the dividing surface of the fixed sleeve and the movable sleeve.