JPH019921Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention relates to a hybrid lens that combines a glass lens and a synthetic resin lens.
In particular, the present invention relates to a hybrid lens suitable for optical pickups and laser collimators for reproducing video discs and compact discs.

Unlike spherical lenses, aspherical lenses are extremely difficult to polish, so with the exception of some special lenses, most of them are made from synthetic resins, which can be easily mass-produced. However, there are some drawbacks when using this synthetic resin aspherical lens in combination with a glass spherical lens. That is, in the past, each lens was held in a lens barrel with a predetermined space between them, making it difficult to align their optical axes and requiring a high level of skill. Furthermore, synthetic resin lenses are prone to deformation due to temperature changes, which causes aberrations and optical axis misalignment. Furthermore, since the synthetic resin lens is spatially arranged as described above, each of the aspherical surfaces on both sides is coated with magnesium fluoride, for example, to prevent contamination from moisture and chemical substances in the atmosphere and to keep the reflectance low. must be coated with a film such as On the other hand, when manufacturing molds,
Two highly sophisticated transfer surfaces corresponding to each aspherical surface are required, which is not desirable in terms of cost.

This idea was devised in view of the above-mentioned drawbacks of the conventional technology.The purpose of this idea was to eliminate the need for adjustments such as optical axis alignment, have high mass production efficiency, and achieve high performance, while also strengthening the cemented state of both lenses. An object of the present invention is to provide a hybrid lens equipped with a locking means that can be held in place.

Hereinafter, this invention will be described in detail with reference to embodiments shown in the accompanying drawings.

As shown in FIG. 1, this hybrid lens 1 includes a first lens 2 made of glass.
and a second lens 3 made of synthetic resin that is integrally bonded to one lens surface of the first lens 2 by injection molding, and the bonded state of these lenses 2 and 3 is firmly maintained. A lens holder 5 is provided.

Referring also to FIG. 2, the lens holder 5
consists of a cylindrical body that is large enough to fit and hold the first lens 2 and whose length is shorter than the thickness of the lens 2, and one end of which is connected to the other lens surface of the first lens 2. An inward stopper flange 5a that engages with the periphery is provided, and an anchor flange 5b bent radially outward at a substantially right angle is formed at the other end. In this example, the first lens 2 is shown as a biconvex spherical lens, but it may also be a concave lens.

On the other hand, the second lens 3 is an aspherical lens made of, for example, polymethyl methacrylate, which has good transparency and is easy to mold. This second lens 3 is injection molded in a mold that will be described later. In this case, the second lens 3 has an edge surface (outer peripheral surface) of the first lens 2 that protrudes from the lens holder 5. 4 and a cylindrical body 6 surrounding the anchor flange 5b of the lens holder 5 are integrally molded. That is, this cylindrical body 6 has an anchor flange 5 at its end.
b, thereby firmly maintaining the bonded state between the first lens 2 and the second lens 3 and preventing them from coming off inadvertently.

To manufacture this hybrid lens 1, molds 10 and 11 having a two-piece structure as illustrated in FIG. 3 are used. In this case, one mold 1
0 is formed with a cylindrical recess 12 having a size to receive the lens holder 5, and a through hole 13 connected to a vacuum pump (not shown) is bored in the center of the bottom of the recess 12. That is,
The first lens 2 is held in the lens holder 5 and then installed in the recess 12. The other mold 11 has a transfer surface 15 for forming the second lens 3 between it and one lens surface of the first lens 2, and the above-described cylindrical body 6 is formed together with the second lens 3. A female mold surface 16 is provided for this purpose. The mold 11 also has the transfer surface 1
A sprue 17 and a runner 18 for injecting molten synthetic resin into the cavity formed between the first lens 2 and the female mold surface 16 are provided.

In the above-mentioned configuration, a buffer agent preferably made of silicone is preferably applied to the recess 12 of one of the molds 10, and then the lens holder 5 holding the first lens 2 is attached, and a vacuum pump (not shown) is operated. to fix the first lens 2. Then, the other mold 11 is closed and the sprue 17 and runner 18 are closed.
By injecting a molten resin such as polymethyl methacrylate into the cavity through the lens holder 5 and allowing a predetermined cooling time, the first lens 2 and the second lens, which are firmly attached through the lens holder 5, are bonded.
A hybrid lens 1 consisting of the lens 3 is obtained.

As is clear from the above description of the embodiment, according to this invention, the first lens 2 made of glass
On the other hand, since the second lens 3 made of synthetic resin is integrally bonded and the bonded state is firmly held via the lens holder 5, the optical axis of those lenses is There is no need for an adjustment process to match the optical axis, and there is almost no risk of the optical axis going out of alignment due to the structure. Further, by being in close contact with a glass lens having high thermal conductivity, the thermal resistance of the synthetic resin lens is alleviated, and thermal deformation due to temperature changes is suppressed as much as possible. Furthermore, since the lens surface of the glass lens is used as the mold surface, only one sophisticated mold transfer surface is required to form the aspherical lens, which is extremely advantageous in mold production. In addition, since only one side of the synthetic resin surface is exposed to the outside, there is an advantage that there are fewer problems with reflection efficiency and cloudiness.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing an embodiment of the hybrid lens of this invention, Fig. 2 is a perspective view of the lens holder shown in Fig. 1, and Fig. 3 is a view shown in Fig. 1. FIG. 2 is a cross-sectional view illustrating a mold structure used for manufacturing a hybrid lens. In the figure, 1 is a hybrid lens, 2 is a first lens, 3 is a second lens, 5 is a lens holder, 6 is a cylindrical body, and 10 and 11 are molds.

Claims (1)

[Scope of utility model registration request] A hybrid lens in which a second lens made of synthetic resin is integrally bonded to one lens surface of a first lens made of glass by injection molding, and the first lens is fitted. It consists of a cylindrical body of a size that can be held together, and one end thereof is provided with an inward stopper flange that engages with the periphery of the other lens surface of the first lens, and the other end is provided with an inward stopper flange that engages with the periphery of the other lens surface of the first lens. A lens holder is provided with an anchor flange bent outward in the radial direction, the first lens is fitted into the lens holder, and the second lens has an anchor flange bent outward in the radial direction. A hybrid lens characterized in that a cylindrical body is formed to surround the edge surface and the anchor flange and is attached to the anchor flange.