JP3230164B2 - Glass molded lens and glass lens mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass molded lens which can be molded with high precision and at low cost by defining a shape other than an optical surface, and a mold for molding the glass.

[0002]

2. Description of the Related Art A molded glass lens is made of a cemented carbide or a ceramic material, and is further provided with a protective coat. The glass is pressed near its softening point by a mold having improved corrosion resistance and oxidation resistance. It is made by molding and transferring optical surfaces and flange surfaces. At this time, two pressure molding methods are known. One is to reduce the distance between the two nests with two nests having optical surfaces for transferring the two optical surfaces of the molded lens and the heated glass in the molding cavity formed by the barrel mold parts. This is a method of molding by pressure filling. The other is that there is no torso or
It is in a position where it does not come into contact with the glass, and it is pressure-formed by reducing the distance between the two nested parts having an optical surface. However, in the outer peripheral direction, the spread of the glass during pressing is not regulated, and the molding transfer is not performed. It is a method. Here, the former is called filling molding, and the latter is called extrusion molding. In the filling molding, since the molding is securely transferred to the outer periphery of the molded lens, in the mounting after molding, the positioning reference of the lens can be used as it is as a contact portion or a fitting portion without post-processing on the outer periphery of the molded lens. In other words, if the eccentricity between the outer peripheral portion and the optical surface is kept small in the mold, no machining is required for the molded lens until assembly. However, in this method, since the cavity volume in the mold is fixed, the volume of the glass must always be smaller than the cavity volume at the time of molding, and usually, a glass material (preform) supplied in a spherical or disk shape is used. There is a drawback that the cost is high since precision is required for the volume control of ()). Further, since the molded outer peripheral portion is in close contact with the body mold, sticking and the like are likely to occur,
In order to reliably remove the molded lens from the mold, it is necessary to provide the mold with a mechanical removal mechanism such as protruding the nest against the body mold. However, since the mold is exposed to a high temperature near the softening point of the glass when the preform is pressed, the sliding portion of the nested driving mechanism is liable to malfunction due to oxidation or mixing of glass powder, It is extremely unreliable. In addition, since a clearance is required to perform sliding, when nesting is driven, the eccentricity accuracy of both types deteriorates due to fitting tolerance. To compensate for this, the machining accuracy of other mold parts that affect eccentricity must be increased, and the cost of the mold also increases.

On the other hand, in the extrusion molding method in which the outer peripheral portion is not regulated at the time of pressure molding, the volume accuracy of the preform may be loose, and since the mold does not have a complicated driving mechanism, both the preform and the mold are inexpensive. Become. Therefore, the extrusion molding method is now becoming popular.

[0004]

However, in this method, if the viscosity of the glass is not strictly controlled at the time of pressure molding, the pressing force is easily relaxed due to the expansion and deformation of the outer peripheral portion, and the optical surface is hardly adhered due to insufficient adhesion with the mold. Transferability is poor. In other words, the temperature and pressure conditions at the time of pressure molding are stricter than those of the filling molding method, and are generally difficult to control. In addition, the outer peripheral portion of the molded lens has no coaxiality with the transferred optical surface at all, and a mounting reference surface (outer peripheral surface) for mounting must be newly created by post-processing such as centering. . This not only increases the cost of post-processing, but also increases the final lens system performance when mounted due to the coaxial accuracy between the optical surface when processing the outer circumference of the molded lens and the processing outer circumference. affect.

Further, since the centering process is performed by sandwiching both formed optical surfaces by a bell clamp, the optical surface is easily scratched at this time, and shavings and the like are repelled during the outer peripheral grinding process. May hurt. Also,
Since water is used as a cooling liquid at the time of the outer peripheral grinding process, clouding called burn is easily generated on the surface of the molded lens.

The problem of scratches and burns is particularly likely to occur in glass types having a low softening point suitable for molding. This is because the substance added at the time of dissolving the glass material in order to lower the softening point is an alkali (Na, K, Li, etc.) that easily forms a hydrate, and the hardness at room temperature decreases as the softening point decreases. That's why.

In order to prevent such scratches and burns, an optical coating such as antireflection may be applied immediately after molding, and then centering may be performed. This is because the optical coat functions as a protective coat on the surface of the glass material while improving the optical characteristics. However, conventionally, when extrusion molding is performed,
Since the molded lens must be set on the coating jig so that the optical surface is not exposed when coating, the coaxiality of the coating jig and the molded lens must be regulated at the outer periphery where the centering process has been performed. Inevitably, the coating process was performed after the centering process. Therefore, in addition to scratches and burns, defects such as film peeling and color change may occur in the coating process due to poor cleaning after centering.

The present invention solves such a problem, and enables a molded lens to be set on a coating jig with high coaxial accuracy without performing centering in the extrusion molding method. The purpose is to be able to perform processing.

It is another object of the present invention to loosen the centering tolerance and thus reduce the cost of the molded lens.

[0010]

This object is achieved by any of the following technical means.

[0011] non-optical surface of (a) glass molded lens, the normal vector direction with respect to the optical axis of the optical surface of 0 ° or at least the light incident side or the light exiting the one conical surface as a surface not 90 °
A glass molded lens provided on one or both sides of the glass.

(B) The length of the conical surface in the optical axis direction is 50
The glass molded lens according to item a, which is not less than μm .

[0013] (c) the transfer surface of the non-optical surface of the mold for the molding in the mold of a glass molded lens, and the normal vector direction of 0 ° or 90 not ° transfer surface with respect to the optical axis of the optical surface
At least one of the conical surfaces on either the light entry side or the light exit side
A glass lens molding die , which is provided on one side or both sides .

(D) The length of the conical surface in the optical axis direction is 50.
The glass lens molding die according to item c, wherein the diameter is not less than μm .

[0015]

FIG. 1 shows a state in which extrusion molding is performed in a mold according to the present invention.

Outside the outer periphery of the optical surfaces 2A and 2B of the upper mold 14 and the lower mold 15, there is an inclined surface 3 whose normal vector is not 0 ° or 90 ° with respect to the optical axis 11, and this surface also has an optical surface. Forming and transferring to glass at the time of forming and pressing together with the surface. The outer periphery of the glass molded lens 1 is a free surface.

[0017] The glass molded lens 1, as shown in FIG. 5, fitted to the inclined surface 3 B of coating jig 17, the optical surface 2A of the glass molded lens 1, 2B exactly coating jig holes 17A,
It can be exposed from 18A. Also, since the thickness between the flange portions 4 and 5 of the glass molded lens 1 is normally transferred from the mold with an accuracy of ± 50 μm or less, if the lid 18 is placed on the back side of the coating jig in this state, the inside of the coating apparatus will be Even if the coating jig 17 is reversed during the coating on the opposite surface, the glass molded lens 1 does not move in the coating jig 17.

FIG. 2 shows an embodiment of a lens in which the slope 3 of the mold is formed into a conical surface and the outer peripheral surface 7 is centered to form a glass. It is good to cut down to the slope when centering.

FIG. 3 shows a square shaped lens 1A in which the slope 3A has a pyramid shape in four directions. By devising the shape of the preform, the amount of protrusion of the protrusion 9 including the flange 4A can be minimized.

FIG. 4 shows that the inclination of the inclined surface 3 of the molded lens 1 is made so close to parallel to the optical axis 11 that the shift of the glass molded lens 1 at the time of mounting on the lens frame (barrel) 13 is achieved. This is an embodiment in which a direction reference plane is used. In this case, since the centering tolerance can be made very loose, the wear amount of the grinding wheel for centering grinding need not be almost checked during the working, so that the centering process can be completely unmanned and the cost can be reduced.

[0021]

According to the present invention, a glass molded lens can be coated at a low cost because it can be coated before centering in a later process, and the molding die can be handled easily. It became possible to make it easy and cheap.

[Brief description of the drawings]

FIG. 1 is a diagram showing a molding process of a molding die and a glass molding lens of the present invention.

FIG. 2 is a perspective view of one embodiment of the glass molded lens of the present invention.

FIG. 3 is a perspective view of another embodiment of the glass molded lens of the present invention.

FIG. 4 is a partial sectional view in which the glass molded lens of the present invention is mounted on a lens barrel.

FIG. 5 is a cross-sectional view in which the glass molded lens of the present invention is mounted on a coating jig.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A Glass molding lens 2A, 2B Optical surface 3 Slope (conical surface) 3A Slope (pyramid slope) 3B Slope (coat jig slope) 4, 5 Flange surface 7 Outer peripheral surface 9 Mold protrusion part 11 Optical axis 13 Lens frame (Lens) 14 Upper die 15 Lower die 17 Coating jig 17A, 18A Coating hole 18 Coating jig lid

Claims (4)

(57) [Claims] 1. A non-optical surface of a glass molded lens having at least one conical surface as a surface whose normal vector direction is not 0 ° or 90 ° with respect to the optical axis of the optical surface, at least on the light incident side or the light exit side.
A glass molded lens provided on either side or both sides . 2. The length of the conical surface in the optical axis direction is 50 μm.
Glass molded lens according to claim 1, wherein the at least. 3. A molding die for a glass molded lens, wherein a non-optical surface of the molding die has a transfer surface whose normal vector direction is not 0 ° or 90 ° with respect to the optical axis of the optical surface .
One conical surface must be at least on either the incoming or outgoing side
Or a mold for molding glass lenses , which is provided on both sides . 4. The length of the conical surface in the optical axis direction is 50 μm.
3. glass lens mold of, wherein the at least.