JP2003206143A - Method for manufacturing rod lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a rod lens which is low-priced and which has high precision. <P>SOLUTION: At least one end face of a rod-shaped vitreous material is heated at a temperature above a glass transition point of the vitreous material to be softened and deformed and the heated face is made to be a curved face form of a projection shape. Especially when the face having curved face form of the projection shape is further press-molded by a metallic die for press molding, curvature of an apex having curved face form of the projection shape is larger than curvature of an apex of the metallic die for press molding. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a rod lens.

[0002]

2. Description of the Related Art Rod lenses are widely used for converging light beams in the optical axis direction and for collimating divergent light. When a homogeneous material with no refractive index distribution is used for the rod lens, both end faces through which the light rays enter and exit are flat surfaces having a surface roughness close to a mirror surface, a convex spherical surface, or a higher-order function higher than a quadratic function. It is often an aspherical shape determined by the above, and at least one surface is often a convex shape. Conventionally, the surface accuracy and surface roughness of both end surfaces are directly processed by mechanical cutting, grinding, polishing, etc. of the end surface of the rod lens according to predetermined design specifications, or processed by a pressing method using a mold appropriately. It was.

The method of processing by mechanical cutting, grinding, polishing, etc. has the drawback of low productivity. When processing at least one surface of the rod lens into a convex shape,
Press molding using a cylindrical rod material whose end surface is flat,
In the molding process, there is a problem that air is trapped in a space formed by the concave mold surface and the rod material surface, and traces of air pools remain on the lens surface after molding. In order to avoid this, it is necessary to use an expensive structure such as providing a die with an air vent or a vacuum forming machine structure.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rod lens manufacturing method which solves the above problems.

[0005]

According to the present invention, at least one end surface of a rod-shaped glass material is heated to a temperature exceeding the glass transition point of the glass material to be softened and deformed, and the heated surface is convex. The present invention provides a method for manufacturing a rod lens, which has a curved surface shape.

Further, in the above method for manufacturing a rod lens, wherein the convex curved surface is further press-molded by a press-molding die, the curvature of the apex of the convex mold before press molding is Provided is a rod lens manufacturing method characterized in that the curvature is larger than the curvature of the apex of a press molding die corresponding to the same apex.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION
A rod-shaped glass material (hereinafter, referred to as a glass rod) cut into a predetermined length is used as a base material, and the material may be glass. In the present invention, the end surface of the glass rod is directed downward (in the direction of gravity), heating means such as flame and hot air, temperature monitoring means for monitoring the temperature state by a thermocouple, and temperature control means for controlling the temperature. By deforming the end surface shape of the glass rod from a flat surface to a desired spherical or aspherical convex shape, a glass rod having no refractive power can be changed to a rod lens having refractive power.

An example of the rod lens manufacturing method of the present invention is shown in FIG. The glass rod 1 of the base material is the end face 2 which is desired to be curved
Is held downward by a jig (not shown). The heat source 3 is placed under the end face portion at an appropriate distance, and hot air 5 of a predetermined temperature is emitted from the jet port 4 of the heat source and is arranged so as to hit the end face 2 of the glass rod 1 for a certain period of time. . Here, while controlling the diameter 6 and the air volume of the hot air jetted from the heat source 3 by using the shielding plate 7 and measuring the temperature of the hot air 5 with the thermocouple 8, the thermal deformation temperature (glass transition temperature, yielding temperature) of the glass material is measured. (Point, softening point, etc.), the end face 2 of the glass rod 1 is gradually softened by keeping it at a higher temperature for a certain period of time while controlling. Then, when the end surface 2 becomes a predetermined spherical surface or aspherical surface due to the balance of surface tension and gravity, the hot air ejected from the heat source is cut, and the temperature is adjusted so as to lower the temperature. It is possible to obtain the rod lens 9 having the curved surface 10 deformed into a shape or an aspherical shape.

Further, by performing the same operation on the other end face, it is possible to obtain a rod lens in which the edge portions of both end faces are deformed into a spherical shape or an aspherical shape.

Here, the heat source 3 may be not only an electric heat source such as a resistance heating element such as a nichrome wire heater or a far infrared heater, but also a flame heat source such as a Bunsen burner or an oxygen burner. Any heat source that emits heat above the transition point may be used. The heat source is preferably one that can be heated to a temperature above the yield point or softening point of the glass material. When using a flame heat source, the position of the heat source may be adjusted so that the flame has the above-mentioned effect of hot air.

A jet port 4 for jetting hot air from a heat source
Is the glass rod 1 for which the diameter 6 of the hot air jetted is the target.
A size that softens the end face 2 of is sufficient. In addition, the temperature of hot air or flame may have a temperature difference between the central part and the peripheral part. For this, an optimum temperature distribution can be obtained by changing the shapes and sizes of the thermocouple 8 and the shielding plate 7. it can. In addition, the heat source 3 and its spout 4
The number is not limited to one, but it is also possible and effective to use a plurality so as to obtain the optimum hot air and flame conditions.

Any material can be used for the glass rod as long as it is softened and deformed by heat, and the composition of the glass is not limited. However, when the glass material containing an oxide that is easily reduced, such as PbO and Bi ₂ O _{3, is} softened by heating by the flame method, black matter such as Pb and Bi reduced by the flame of the flame is deposited on the surface. In some cases, a light shielding part is formed. Therefore, in this case, it is preferable that the curved surface is formed by hot air from an electric heat source such as the above-mentioned heater.

The end surface 2 of the glass rod 1 is not limited to a flat surface. Further, the surface roughness of the end surface 2 is not necessarily a mirror surface because it becomes a smooth curved surface due to the surface tension of the softened end surface, but when it is desired to make the surface roughness of the target curved surface equal to that of a good polished surface, , End face 2 of glass rod 1
Is preferably a surface free from scratches and craters and which is as close to a mirror surface as possible.

In the present invention, the convex curved surface can be further press-molded with a press molding die. In that case, the curvature of the apex of the convex curved surface is the same. It is preferable that the curvature is larger than the curvature of the apex of the press-molding die corresponding to. By doing so, the air in the closed space formed by the mold surface and the rod lens surface is not confined in the central part of the lens surface, but escapes to the peripheral part outside the effective diameter of the lens surface, so a precise shape without air pool A rod lens having is obtained.

Further, in the present invention, by heating the glass material to a temperature exceeding its glass transition point to soften it,
It is possible to obtain a rod lens or a glass material for a rod lens that does not have corners on the edge part, which makes it possible to obtain a rod lens with a precise shape that does not cause burrs, chips or scattering of the glass cullet at the lens edge part. To be

[0016]

EXAMPLES Example 1 Composition shown in Table 1 (unit: mol%)
Of the glass materials of No. Table 1 for material 1
We made a cylindrical glass rod with the outer diameter and length shown in
Both end surfaces were finished with a flat polished surface. Next, with a resistance heater using a nichrome wire as a heat source, the position of the heat source so that the hot air sent by the fan has a temperature higher than the yield point of the glass material at the position of the thermocouple arranged near the end surface of the glass rod. By controlling the temperature and holding the glass rod end face gradually for a while until it becomes an almost spherical shape, and then immediately stopping the air blow, a plano-convex rod lens with an almost smooth spherical shape on one side can be obtained. It was

Furthermore, by performing the same operation on the other end surface, a biconvex rod lens having substantially smooth spherical edge portions on both end surfaces was obtained.

Further, the composition No. of Table 1 was determined. For the glass materials of Nos. 2 to 4, the above composition No. In the same manner as in No. 1, the temperature of the heat source was controlled to be higher than the yield point of each glass material, and heat-softening molding was performed to obtain a rod lens having a substantially spherical end surface.

(Example 2) Of the glass materials having the composition (unit: mol%) shown in Table 1, composition No. For the materials 5 and 6, columnar glass rods having the outer diameters and the lengths shown in Table 1 were manufactured, and both end surfaces were subjected to a flat polished surface finish. Next, as shown in FIG. 5, an oxygen burner is used as a heat source, and the heat generated by the flame is controlled so that the heat is higher than the yield point of the glass material at the position of the thermocouple arranged near the end surface of the rod material. Then, the glass rod end surface was gradually softened and held for a time until it had a substantially spherical shape, and then the flame was quickly cut off to obtain a plano-convex rod lens having a substantially smooth spherical shape. Further, similarly, by performing the same operation on the other end face, a biconvex rod lens having substantially smooth spherical edge portions on both end faces was obtained. The numbers in FIG. 5 are the same as those used in FIG.

Example 3 Composition No. 1 in Table 1 In order to obtain a precise plano-convex aspherical rod lens for the glass material of No. 1 using the rod lens obtained in Example 1 as a base material, the plano-convex rod lens obtained in Example 1 was used as shown in FIG. A concave aspherical mold 13 having a vertex curvature 12 smaller than the vertex curvature 11 of 10 is processed, while a mold 15 having a planar shape 14 is prepared, and these molds are precision glass press molded. It is assembled as a core mold of a machine, and the spherical surface of the plano-convex rod spherical lens is placed on the surface of the concave aspherical shape mold (it is facing downward in FIG. 2, but it may be reversed), and the composition of Table 1 is used. No. Both molds were heated to a temperature range exceeding the yield point temperature shown in the column 1 and pressurized at 200 N for about 10 seconds, and then naturally cooled for about 10 minutes, and the rod lens was taken out from the mold. The aspherical shape of the press-molded surface of this rod lens shows a clean appearance without any dents such as air pocket marks. When the aspherical shape is measured with a three-dimensional shape measuring machine, it is precisely processed into an aspherical shape. It was found that it had a good aspherical shape that almost matched the mold surface. Further, the planar shape of the other end has no burrs, chips or scattering of the glass cullet at the edge portion, and when the planar shape is measured by a three-dimensional shape measuring machine, it has a good planar shape that substantially matches the mold. I knew that.

(Example 4) On the other hand, as shown in FIG. 3, with respect to the same combination of concave aspherical mold 13 and flat mold 15 produced in Example 3, a glass rod 16 having flat end surfaces was used. The lens was placed in the mold and molded under the same molding conditions as in Example 3, and the lens was taken out of the mold. The flat surface 14 on the flat mold side of this lens was cleanly transferred to the lens surface after molding, but a chip 21 or scattered glass cullet 2 at the edge portion.
2 was seen. During molding, the glass confined in the space formed by the flat mold side wall surface 14 and the ring mold inner wall surface of FIG. It is presumed that it adhered to the surface.

Further, as shown in FIG. 4, the lens surface on the side of the aspherical mold had a large circular dent 18 near the center, and the transferability of the aspherical shape was insufficient.

During molding, the air trapped in the space formed by the aspherical surface 12 of the concave aspherical mold 13 and the flat surface 17 of the glass rod in FIG. 3 is compressed and can escape to the peripheral portion. It is presumed that a perfect circular recess mark 18 was formed on a part of the aspherical lens surface instead.

[0024]

[Table 1]

[0025]

According to the present invention, when at least one surface of the rod lens is processed into a convex spherical surface or an aspherical mirror surface, it is expensive due to mechanical cutting, grinding and polishing as in the conventional case. It is possible to manufacture by an inexpensive method without using the method.

Also, when the rod lens is manufactured by press molding, the air in the closed space formed by the die surface and the rod lens surface is not confined in the central portion of the lens surface, but around the outside of the effective diameter of the lens surface. By letting it escape to the portion, it becomes possible to manufacture a rod lens having a precise end face shape without air pockets without using an expensive air vent structure or a vacuum forming method. Further, it becomes possible to manufacture a rod lens having a precise shape without causing burrs, chips, and scattering of the glass cullet at the edge portion of the lens.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of the present invention.

FIG. 2 is a conceptual diagram showing an example of the present invention.

FIG. 3 is a conceptual diagram showing a comparative example.

FIG. 4 is a side view showing a rod lens manufactured according to a comparative example.

FIG. 5 is a conceptual diagram showing another example of the present invention.

[Explanation of symbols]

1: Glass rod 2: End face 3: Heat source 4: Ejection port 5: Hot air 7: Shield plate 8: Thermocouple 9: Rod lens

Claims (2)

[Claims] 1. At least one end surface of a rod-shaped glass material is heated to a temperature exceeding the glass transition point of the glass material to be softened and deformed, and the heated surface is made into a convex curved surface shape. And a method for manufacturing a rod lens. 2. The method of manufacturing a rod lens according to claim 1, wherein the convex curved surface is further press-molded by a press-molding die, and the apex of the convex mold before press molding. Is larger than the curvature of the apex of the press-molding die corresponding to the same apex.