This application is based on Japanese Patent Application No. 2010-261225 filed with the Japan Patent Office on Nov. 24, 2010, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a glass optical element, a method of producing thereof and a mold, and more particularly to a glass optical element with a positioning protrusion formed thereon, a method of producing the glass optical element, and a mold for use in production of the glass optical element.
2. Description of the Related Art
A glass optical element is produced by press molding a molten glass with a mold (see Japanese Laid-Open Patent Publication No. 2004-256381). Referring to
Referring to
Upper mold 110 has a flat lower end surface 111 and a spherically-shaped molding surface 112 provided concavely. Lower mold 120 has a flat upper end surface 121, a spherically-shaped molding surface 122 provided convexly, and recesses 123 intermittently provided concavely around molding surface 122. Recesses 123 are used to form positioning protrusions on a glass optical element. These protrusions are used when the glass optical element is attached to a substrate or the like.
Referring to
Referring to
However, as shown in
The present invention has an object to provide a glass optical element with a positioning protrusion formed thereon favorably, a method of producing the glass optical element, and a mold for use in production of the glass optical element.
A mold based on the present invention is a mold for use in production of a glass optical element, including an upper mold provided with a first molding surface, and a lower mold on which a molten glass is dropped, the lower mold being provided with a second molding surface for press molding the molten glass with the first molding surface. A recess for forming a positioning protrusion on the glass optical element is provided at an outer side of one of the first molding surface and the second molding surface. An inclined section is provided at an inner circumferential surface of the recess closer to the one of the first molding surface and the second molding surface. The inclined section is inclined or curved such that, when the molten glass dropped on the second molding surface spreads toward the outer side, the molten glass enters the recess while maintaining contact with the inclined section.
Preferably, the inclined section is formed flat, and an angle formed by the inclined section and a pressing direction in which the upper mold and the lower mold press the molten glass is more than or equal to 45° and less than or equal to 70°.
Preferably, a plurality of the recesses are provided at the outer side of the one of the first molding surface and the second molding surface. Preferably, the recess is provided at the outer side of the second molding surface.
A method of producing a glass optical element based on the present invention press molds the molten glass using the mold based on the present invention, thereby producing the glass optical element.
A glass optical element based on the present invention is produced by press molding the molten glass using the mold based on the present invention.
According to the present invention, a glass optical element with a positioning protrusion formed thereon favorably, a method of producing the glass optical element, and a mold for use in production of the glass optical element can be obtained.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
Each embodiment and each example based on the present invention will be described below with reference to the drawings. It is noted that, when the number, amount and the like are mentioned in the description of each embodiment and each example, the scope of the present invention is not necessarily limited to that number, amount and the like unless otherwise specified. In the description of each embodiment and each example, identical and corresponding parts are denoted by an identical reference character, and repeated description thereof may not be provided. The features of the respective embodiments and examples have been initially intended to be used in combination as appropriate.
Referring to
(Mold 100)
Referring to
A protective film (not shown) against a molten glass 41 (see
Lower mold 20 has a flat upper end surface 21, a spherically-shaped molding surface 22 (a second molding surface) provided convexly, and at least one recess 23 provided concavely around molding surface 22. Four recesses 23 can be provided at intervals of 90°, for example, in a circumferential direction about molding surface 22. Recess 23 is fondled into a cone, a polygonal pyramid or a frustum, for example. As used herein, frustum means a configuration obtained by cutting away the top portion of a polygonal pyramid, such as a pyramid, or a cone, for example, along a plane of a smaller area than the bottom.
A protective film (not shown) against molten glass 41 (see
Referring to
A flat surface 22A extending horizontally away from molding surface 22 is provided at the outer side of molding surface 22. Recess 23 includes an inclined section 23A, a bottom section 23B, and a rear section 23C, as inner circumferential surfaces. Recess 23 in the present embodiment has a depth H of 0.4 mm.
Inclined section 23A is located closer to molding surface 22, and continues to flat surface 22A. Inclined section 23A is inclined such that, when molten glass 41 dropped toward molding surface 22 contacts (hits) molding surface 22 and thereby spreads outwardly, molten glass 41 enters recess 23 (see arrow AR1) while maintaining contact with inclined section 23A.
In the present embodiment, inclined section 23A is inclined at an angle θ1 in the pressing direction in which upper mold 10 (see
Angle θ1 is set such that molten glass 41 enters recess 23 (see arrow AR1) while maintaining contact with inclined section 23A, in accordance with the viscosity of molten glass 41, the temperature of molten glass 41, the drop height of molten glass 41 relative to lower mold 20, and the like.
For example, the higher the viscosity of molten glass 41, the higher the surface tension of molten glass 41 spreading from molding surface 22 toward flat surface 22A. Under the action of the surface tension of molten glass 41, molten glass 41 is less likely to enter recess 23. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. Angle θ1 may be increased within such a range that a positioning protrusion 44 (see
The lower the viscosity of molten glass 41, the lower the surface tension of molten glass 41 spreading from molding surface 22 toward flat surface 22A. Molten glass 41 is more likely to enter recess 23. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. As angle θ1 decreases, positioning protrusion 44 (see
The higher the temperature of molten glass 41, the lower the viscosity of molten glass 41. The surface tension of molten glass 41 spreading from molding surface 22 toward flat surface 22A decreases. Molten glass 41 is more likely to enter recess 23. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. As angle θ1 decreases, positioning protrusion 44 (see
The lower the temperature of molten glass 41, the higher the viscosity of molten glass 41. The surface tension of molten glass 41 spreading from molding surface 22 toward flat surface 22A increases. Under the action of the surface tension of molten glass 41, molten glass 41 is less likely to enter recess 23. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. Angle θ1 may be increased within such a range that positioning protrusion 44 (see
The greater the drop height of molten glass 41 relative to lower mold 20, the greater the shock when molten glass 41 contacts (hits) molding surface 22, and the higher the kinetic energy with which molten glass 41 tends to spread from molding surface 22 toward flat surface 22A. Molten glass 41 is less likely to enter recess 23. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. Angle θ1 may be increased within such a range that positioning protrusion 44 (see
The smaller the drop height of molten glass 41 relative to lower mold 20, the smaller the shock when molten glass 41 contacts (hits) molding surface 22, and the lower the kinetic energy with which molten glass 41 tends to spread from molding surface 22 toward flat surface 22A. Molten glass 41 is more likely to enter recess 23. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. As angle θ1 decreases, positioning protrusion 44 (see
Angle θ1 may be optimized in accordance with the viscosity of molten glass 41, the temperature of molten glass 41, the drop height of molten glass 41 relative to lower mold 20, and the like such that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A and such that a positioning protrusion that will be formed on glass optical element 45 by means of recess 23 can exert a high positioning function.
Bottom section 23B continues to the lower end of inclined section 23A. Bottom section 23B extends horizontally away from inclined section 23A. Rear section 23C continues to the leading end of bottom section 23B in the extending direction. Rear section 23C continues to a flat surface 22B provided horizontally at the inner side below upper end surface 21.
Rear section 23C is inclined at an angle θ2 in the pressing direction in which upper mold 10 (see
A distance D between the upper end of inclined section 23A and the upper end of rear section 23C is 4 mm. Upper mold 10 and lower mold 20 as mold 100 are configured as described above.
(Method of Producing Glass Optical Element)
Referring to
(Step ST1)
Referring to
Part of molten glass 40 in the melting furnace is conveyed through nozzle 30 to the lower end of nozzle 30 to be exposed as molten glass 41 at the lower end of nozzle 30. Molten glass 41 is accumulated at the lower end of nozzle 30 by surface tension. The viscosity of molten glass 41 is, for example, 101 to 1010 Poise, and preferably 103 to 107 Poise.
(Step ST2)
Referring to
(Step ST3)
Referring to
In the present embodiment, inclined section 23A of recess 23 (see
(Step ST4)
Referring to
(Step ST5)
Referring to
Molten glass 41 is pressed with molding surface 12 of upper mold 10 and molding surface 22 of lower mold 20 in a high-temperature atmosphere. Means for moving lower mold 20 (or upper mold 10) so as to press molten glass 41 may be implemented by an air cylinder, an oil hydraulic cylinder, a motor cylinder through use of a servomotor, or the like.
Molten glass 41 spreads between molding surfaces 12 and 22, and also enters recess 23 to spread inside recess 23. Molten glass 41 is heat radiated (dissipated) by means of upper mold 10 and lower mold 20. By solidification of molten glass 41, glass optical element 45 with positioning protrusion 44 formed thereon is obtained.
Referring to
As indicated by an arrow AR6, protrusions 44 are fitted into recesses 52. Protrusion 44 is fitted with the inner circumferential surface of recess 52 by means of an outer side surface 44B and an inner side surface 44A of protrusion 44. By this fitting, glass optical element 45 is positioned relative to substrate 50. Glass optical element 45 is fixed to substrate 50 with an adhesive (not shown) or the like while being positioned. With glass optical element 45 having protrusions 44, glass optical element 45 can easily be attached to substrate 50.
Referring to
(Function and Effect)
Referring again to
By solidification of molten glass 41 spread inside recess 23, positioning protrusion 44 can be formed favorably on glass optical element 45 (see
(Variation of First Embodiment)
Referring again to
Inclined section 23A may be inclined such that, when molten glass 41 is pressed with upper mold 10 and lower mold 20 to spread outwardly (see step ST5 in the above-described first embodiment), molten glass 41 enters recess 23 while maintaining contact with inclined section 23A. In this case, angle θ1 of inclined section 23A is set such that molten glass 41 enters recess 23 while maintaining contact with inclined section 23A, in accordance with the viscosity of molten glass 41, the temperature of molten glass 41, the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, and the like.
For example, the greater the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, the greater the force with which molten glass 41 is pushed into recess 23. Molten glass 41 is more likely to enter recess 23. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. As angle θ1 decreases, positioning protrusion 44 (see
The smaller the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, the smaller the force with which molten glass 41 is pushed into recess 23. Molten glass 41 is less likely to enter recess 23. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 23 while maintaining contact with inclined section 23A. Angle θ1 may be increased within such a range that positioning protrusion 44 (see
Referring to
In the mold according to the present embodiment, inclined section 23A of recess 23 in lower mold 20 is curved. Inclined section 23A continues to flat surface 22A, and is curved such that, when molten glass 41 dropped toward molding surface 22 contacts (hits) molding surface 22 and thereby spreads outwardly, molten glass 41 enters recess 23 (see arrow AR1) while maintaining contact with inclined section 23A.
Inclined section 23A may be curved and inclined such that, when molten glass 41 is pressed with upper mold 10 and lower mold 20 to spread outwardly (see step ST5 in the above-described first embodiment), molten glass 41 enters recess 23 while maintaining contact with inclined section 23A.
Molten glass 41 can enter recess 23 by the contact with inclined section 23A even under the action of the surface tension of molten glass 41 generated when molten glass 41 spreads outwardly and the like. The mold according to the present embodiment can achieve similar function and effect to those of mold 100 according to the above-described first embodiment.
Referring to
In the present embodiment, inner side surface 44A is curved unlike the above-described first embodiment. When glass optical element 45 is positioned on substrate 50, the contact between outer side surface 44B and the inner circumferential surface of recess 52 mainly causes positioning protrusion 44 to exert its function.
Referring to
Referring to
Lower mold 20 has flat upper end surface 21 and spherically-shaped molding surface 22 (a second molding surface) provided convexly. A protective film (not shown) against molten glass 41 may also be formed previously on each surface of upper end surface 21 and molding surface 22.
Referring to
A flat surface 12A extending horizontally away from molding surface 12 is provided at the outer side of molding surface 12 of upper mold 10. Recess 13 includes an inclined section 13A, a bottom section 13B, and a rear section 13C, as inner circumferential surfaces. Recess 13 in the present embodiment has a depth H of 0.4 mm.
Inclined section 13A is located closer to molding surface 12, and continues to flat surface 12A. Inclined section 13A is inclined such that, when molten glass 41 is pressed with upper mold 10 and lower mold 20 to spread outwardly, molten glass 41 enters recess 13 (see an arrow AR7) while maintaining contact with inclined section 13A.
In the present embodiment, inclined section 13A is inclined at angle θ1 in the pressing direction in which upper mold 10 (see
Angle θ1 is set such that molten glass 41 enters recess 13 while maintaining contact with inclined section 13A, in accordance with the viscosity of molten glass 41, the temperature of molten glass 41, the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, and the like.
For example, the higher the viscosity of molten glass 41, the higher the surface tension of molten glass 41 spreading from molding surface 12 toward flat surface 12A. Under the action of the surface tension of molten glass 41, molten glass 41 is less likely to enter recess 13. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. Angle θ1 may be increased within such a range that positioning protrusion 44 (see
The lower the viscosity of molten glass 41, the lower the surface tension of molten glass 41 spreading from molding surface 12 toward flat surface 12A. Molten glass 41 is more likely to enter recess 13. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. As angle θ1 decreases, positioning protrusion 44 (see
The higher the temperature of molten glass 41, the lower the viscosity of molten glass 41. The surface tension of molten glass 41 spreading from molding surface 12 toward flat surface 12A decreases. Molten glass 41 is more likely to enter recess 13. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. As angle θ1 decreases, positioning protrusion 44 (see
The lower the temperature of molten glass 41, the higher the viscosity of molten glass 41. The surface tension of molten glass 41 spreading from molding surface 12 toward flat surface 12A increases. Under the action of the surface tension of molten glass 41, molten glass 41 is less likely to enter recess 13. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. Angle θ1 may be increased within such a range that positioning protrusion 44 (see
For example, the greater the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, the greater the force with which molten glass 41 is pushed into recess 13. Molten glass 41 is more likely to enter recess 13. In this case, angle θ1 can be decreased within such a range that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. As angle θ1 decreases, positioning protrusion 44 (see
The smaller the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, the smaller the force with which molten glass 41 is pushed into recess 13. Molten glass 41 is less likely to enter recess 13. In this case, angle θ1 may be increased such that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A. Angle θ1 may be increased within such a range that a positioning protrusion 44 (see
Angle θ1 may be optimized in accordance with the viscosity of molten glass 41, the temperature of molten glass 41, the degree that molten glass 41 is pressed with upper mold 10 and lower mold 20, and the like such that molten glass 41 can enter recess 13 while maintaining contact with inclined section 13A and such that a positioning protrusion that will be formed on glass optical element 45 by means of recess 13 can exert a high positioning function.
Bottom section 13B continues to the upper end of inclined section 13A. Bottom section 13B extends horizontally away from inclined section 13A. Rear section 13C continues to the leading end of bottom section 13B in the extending direction. Rear section 13C continues to a flat surface 12B provided horizontally at the inner side above lower end surface 11.
Rear section 13C is inclined at angle θ2 in the pressing direction in which upper mold 10 (see
Distance D between the lower end of inclined section 13A and the lower end of rear section 13C is 4 mm. Upper mold 10 and lower mold 20 as mold 100A are configured as described above.
Referring to
Molten glass 41 is pressed with molding surface 12 of upper mold 10 and molding surface 22 of lower mold 20 in a high-temperature atmosphere. Molten glass 41 spreads between molding surfaces 12 and 22. Molten glass 41 enters recess 13, and spreads inside recess 13 (see arrow AR7). Molten glass 41 is heat radiated (dissipated) by means of upper mold 10 and lower mold 20. By solidification of molten glass 41, glass optical element 45 with positioning protrusion 44 formed thereon is obtained.
(Function and Effect)
Referring again to
By solidification of molten glass 41 spread inside recess 13, positioning protrusion 44 can be formed favorably on glass optical element 45 (see
The results of Experiment 1 conducted based on the above-described first embodiment will be described. As will be described later in detail with reference to
Referring to
Referring to
Bottom section 23B continues to the lower end of inclined section 23A. Bottom section 23B extends horizontally away from inclined section 23A. As shown in
As shown in
Referring to
In Example 1A, angle θ1 was 45°. The temperature of the molten glass being dropped to lower mold 20A was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 1A, the temperature of the molten glass when transfer had been accomplished was 1040°. It can be seen that, when angle θ1 is 45°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 1040°.
In Example 1B, angle θ1 was 60°. The temperature of the molten glass being dropped to lower mold 20A was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 1B, the temperature of the molten glass when transfer had been accomplished was 960°. It can be seen that, when angle θ1 is 60°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 960°.
In Example 1C, angle θ1 was 70°. The temperature of the molten glass being dropped to lower mold 20A was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 1C, the temperature of the molten glass when transfer had been accomplished was 940°. It can be seen that, when angle θ1 is 70°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 940°.
In Comparative Example 1, angle θ1 was 30°. The temperature of the molten glass being dropped to lower mold 20A was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Comparative Example 1, the molten glass did not enter recess 23, and transfer was not accomplished. No positioning protrusion was formed.
The results of Experiment 1 reveal that a favorable protrusion is formed on a glass optical element by setting angle θ1 at more than or equal to 45° and less than or equal to 70°.
The results of Experiment 2 conducted based on the above-described first embodiment will be described. As will be described later in detail with reference to
Referring to
Referring to
Bottom section 23B continues to the lower end of inclined section 23A. Bottom section 23B extends horizontally away from inclined section 23A. As shown in
As shown in
Referring to
In Example 2A, angle θ1 was 45°. The temperature of the molten glass being dropped to lower mold 20B was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 2A, the temperature of the molten glass when transfer had been accomplished was 1060°. It can be seen that, when angle θ1 is 45°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 1060°.
In Example 2B, angle θ1 was 60°. The temperature of the molten glass being dropped to lower mold 20B was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 2B, the temperature of the molten glass when transfer had been accomplished was 1000°. It can be seen that, when angle θ1 is 60°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 1000°.
In Example 2C, angle θ1 was 70°. The temperature of the molten glass being dropped to lower mold 20B was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Example 2C, the temperature of the molten glass when transfer had been accomplished was 980°. It can be seen that, when angle θ1 is 70°, a favorable positioning protrusion is obtained by setting the temperature of the molten glass at 980°.
In Comparative Example 2, angle θ1 was 30°. The temperature of the molten glass being dropped to lower mold 20B was raised in increments of 20° C., and a measurement was made as to whether or not the molten glass at each temperature had entered (had been transferred to) recess 23. In Comparative Example 2, the molten glass did not enter recess 23, and transfer was not accomplished. No positioning protrusion was formed.
The results of Experiment 2 reveal that a favorable protrusion is formed on a glass optical element by setting angle θ1 at more than or equal to 45° and less than or equal to 70°.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being interpreted by the terms of the appended claims.
Number | Date | Country | Kind |
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2010-261225 | Nov 2010 | JP | national |