JPS5939527A - Plastic lens - Google Patents

Abstract

PURPOSE:To provide the plastic lens for an optical instrument which is high in dimensional accuracy and free from any deformation of curved surfaces due to heat, by a method wherein the outside periphery of an annular edge part provided on the outside of an effective diameter of a lens and extending on both sides or one side of the lens in the direction of the optical axis of the lens is machined for core making work. CONSTITUTION:The annular edge part 13 extending on both sides or one side of a lens in the direction of the optical axis of the lens is provided while leaving a sufficient allowance 7 on the outside of the effective diameter 6 of the lens, and the outside periphery 8 of the edge part 13 is machined for core making to obtain the plastic lens 10. EFFECT:Since cutting heat at the time of machining for core making is generated at a part on the outside of the effective diameter 6 of the lens, thermal deformation of the curved surface within the range of the effective diameter 6 can be perfectly prevented. When combining a plurality of lenses, the spacing between the lenses can be maintained with high accuracy without using any other component part. Further, inclination of the lens can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to plastic lenses, and is suitable for plastic lenses used in optical devices that require height and viscosity, such as ρ, precision tlQ51 nails, camera inspection lenses, lenses for optical sensors, etc. Cook.

The present invention provides light from a lens provided outside the actual effective area of the plastic lens. The object of the present invention is to obtain a high-precision plastic lens whose curved surface is not deformed by heat by centering the outer periphery of a curved soft part extending on both sides of the direction or on the piece I11.

Conventionally, the manufacturing process of lenses using glass materials usually involves two master craftsmen's processes such as roughening, sanding, polishing, centering, etc. of the press phase.

The 1st F is a glass lens (1). According to the manufacturing process described above, both curved surfaces (1a) and (lb) of the glass lens (1) are individually polished in each side process, and after polishing is completed, the lens is chucked from both sides. King, rotate it at high speed, and make a biconvex Th(
The optical axes of la) and (lb) are automatically aligned, and the outer diameter is parallel to the opposite axis (:H) with high precision.
Finishing and making the diameter to the specified size is the work of the heart.

On the other hand, in recent years, plastic lenses? JmM Various types of housings have been developed, and they are becoming used in large quantities, but plastic materials generally have a lower refractive index than glass materials, so the radius of curvature is smaller than necessary for lens design. , which is a precept and extremely difficult, and the refractive index is unstable with respect to changes in humidity.

In addition, it has inherent disadvantages as a material, such as being hygroscopic, having a large expansion coefficient, and being easily damaged due to its low hardness. However, plastic materials have the advantage of being inexpensive and can be supplied in large quantities, so if a high degree of precision is not required, depending on the purpose of use, the location of use, etc. It is suitable for use.For example, it can be used as a finder or magnifying glass with a single lens, or it can be used as a low-magnification Bodatsu cast or microscope lens by combining 3 or 4 lenses, and it has also been used in low-grade cameras with a combination of multiple lenses. Plastic lenses, which do not require a high degree of precision, are usually used in the as-molded form for the purpose of supplying them at low cost. In addition to being made from a material that has the same properties as the original, it also has the following unavoidable drawbacks due to its molding process.

The manufacturing process for plastic lenses differs from the normal manufacturing process for glass lenses in that the biconvex surfaces and outer diameter of the lens are completed at the same time, and this is the reason why plastic lenses can be supplied in large quantities at low cost. However, the accuracy is doubled due to the shape of the lens.

That is, as shown in 2nd pl-Figure 5, (2),
(3) is a convex lens, (4) is a concave lens, and convex lens (2
), (3) The concave lenses (4) are each indica 5 injection molded. Figure 5 is a side view of the concave lens (4), where (6) indicated by the dotted line is the actual effective diameter, and (7) is the lens effective diameter formed with sufficient margin outside of the actual effective diameter (6). (Actual effective diameter (6), lens effective diameter (7)
) is usually transparent, but can be made opaque)
. The CD surface is the parting line and is the contact surface between the fixed mold and the movable mold, and the lens effective diameter (
7) has sufficient draft angle (12) as shown in the figure.
It is usual to add . Therefore, the outermost diameter of the as-molded plastic lens has a pointed shape, and furthermore, the uncut portion (5) of the hot water pouring gate remains in a part of the outermost diameter.

Figure 6 is a sectional view of the main parts of the mold for molding the lens (2). E) and (F) are provided. The outer diameters of the nested parts (E) and (F) are finished to the same dimensions as the effective diameters (6) of their respective biconvex surfaces, and the radius of curvature (design value) and wavelength of each curved surface are One side is finished to an accuracy of 6 degrees within a fraction of a culm degree, and this is used as a fixed type (E') and a movable type (E').
F/), and are fixed and molded so that the center thickness of the lens becomes a predetermined value. When manufacturing these nesting parts (E) and (F), we first select a material with a stable molecular structure that is non-caustic and free of foreign matter, and first set the outer diameter to the effective diameter of the lens. Finish to the same dimensions as (7), and then, using the outer diameter as a reference, rough polish, medium polish, furnace tempering (east hollow is preferable), etc. on one end surface until the specified curvature and high viscosity match. The center line of the outer diameter of the nesting part and the
It cannot be guaranteed that the optical axis of the finished curved surface matches with high precision. This is similar to the core frame work for glass lenses, where one end surface of the insert is finished with a cast surface, the other end surface is finished with a flat surface, and then the outer diameter is determined by the effective diameter (7) of the lens. This is because it is generally difficult to achieve the desired result. Furthermore, manufacturing tolerances in the fit between the nesting part and the respective molds and the mating ends of both molds are also added. For example, in a convex lens (2), the tip of the tip center line of outer diameter,
It is clear that it is even more difficult to guarantee that the three optical axes of the biconvex surfaces coincide with each other with high precision.

Therefore, if precision is not required, use the molded shape with only the gate opening cut, but if precision is required, such as using a single lens or a combination of multiple lenses, the actual effective diameter of the molded lens. (6) and the lens effective diameter (7) provided on the outside thereof may be scratched during centering by chucking from both sides). Perform centering processing.

It is necessary to finish the center line of the outer diameter so that it coincides with the optical axis of both convex surfaces with high precision.

Now, the plastic lens (2) is molded as shown in Figure 6.
In this process, we applied the centering J process to create a pointed lens outer diameter (G
), the cutting heat is higher for plastic materials than for glass materials, and there is a risk that the shape of the curved surface of the actual effective diameter portion (6) of the lens may be deformed due to the high heat.

In this way, when used as a high-precision plastic lens, it cannot be used as is, and must be center-centered, and the conventional shape has the following drawbacks during center-centering processing. has.

1) During centering, a portion close to the lens effective diameter (7) is cut, so the design value of the curved surface cannot be faithfully maintained due to thermal deformation due to cutting.

2) When a plurality of lenses are used in combination, a separate component with a high degree of l'IJ is required to maintain the distance between the lenses with high precision.

3) Ordinary molded plastic lenses have a pointed outer periphery, which causes the lens to fall (tilt) after assembly.

In view of the above-mentioned drawbacks, the present invention has been made to solve this problem.Embodiments of the present invention will now be described in detail with reference to FIG. 7 and the subsequent drawings.

Components that are the same as those in the conventional example are given the same sign and their description will be omitted.

FIG. 7 shows a convex lens (10), which is molded from a plastic material and has an actual effective diameter (6) and a lens effective diameter (7).

In addition, an annular edge (
13) are integrally molded. If the outer periphery of this edge (13) is centered at the position of cut 1i + (8) in the optical axis direction, the heat generating part is located -C from the actual effective diameter (6) of the lens (10), so the actual Deformation of the curved surface within the effective diameter (6) can be completely prevented, and the design value can be faithfully maintained in terms of lens shape.

Figure 8 shows a concave lens (11), and similarly the edge (13).
is molded.

When using a combination of multiple lenses, as shown in Figure 9, combine multiple lenses (x4), (15) and (16), fit them into the lens frame (17), and secure them with the fixing screws (18). ing. At that time, they are lenses (14)s (15
) s (16) in order to maintain the mutual spacing with high precision, the edges (
When cutting both end faces of 13) along the perpendicular cutting line (9) to the optical axis, the distance from that end face to the vertex of the lens on that end face side must be kept within the actual effective diameter (6) of the lens. It is also possible to finish the lens with high precision so that it does not deteriorate, and the lens spacing can be maintained without using separate parts.

Furthermore, when an ordinary molded plastic lens with a pointed shape is fitted into the lens frame (17), the fitting between the two forms a line contact, which may cause the lens to fall (tilt). However, the edge provided in the above trace (1
As for 3), since the width can be determined arbitrarily long, when the two are fitted together, the inclination of the lens can be much reduced compared to the conventional case.

Note that the first part is not limited to the above embodiment, and may be provided so as to extend only on one side in the optical axis direction.

The present invention is constructed as described above, and since the annular edge is provided, the heat generated during core numbering does not affect the actual effective diameter of the lens, and the deformation of the curved surface within the actual effective diameter is completely suppressed. It is possible to prevent this and maintain the design of the lens faithfully.

In addition, when combining multiple lenses, by cutting the edges, the distance between each lens can be maintained without using separate parts as in the past11.10 Also, the inclination of the lens It has the effect of reducing the amount.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional convex glass lens, Figures 2 and 3 are convex lenses of conventional plastic molded lenses, Figure 4 is a sectional view of a concave lens, and Figure 5 is a side view of a conventional plastic molded lens. Figure 6 is a cross-sectional view of the main parts of a mold for molding a convex lens, Figure 7 and the following figures show implementation example 1 of the present invention, Figure 7 is a cross-sectional view of a convex lens to which the present invention is applied, and Figure 8 is FIG. 9 is a cross-sectional view of a concave lens according to another embodiment, and is a cross-sectional view when a plurality of the same lenses are combined. (6) -------Actual effective diameter (7)...Lens effective diameter (10)...Convex lens (11)...Concave lens -□- 136-

Claims (1)

[Claims] This plastic lens is characterized by leaving ample margin outside the actual effective diameter of the lens.