Optical lenses and processes of manufacture

• US 5,994,248 A
• Filed: 11/06/1997
• Issued: 11/30/1999
• Est. Priority Date: 09/25/1995
• Status: Expired due to Fees

• Current Assignee: Saint-Gobain Vitrage
• Original Assignee: Saint-Gobain Vitrage
• Inventors: Gandarillas-Lastra, Jose Francisco, Trouille, Benoit
• Primary Examiner(s): MARCHESCHI, MICHAEL A
• Application Number:
  US08/836,674
• Time in Patent Office: 754 Days
• Field of Search: 501/65, 501/66, 501/68, 501/69, 501/70, 501/72, 501/55, 501/900, 65/66, 65/83, 65/68, 65/37, 65/111, 65/275, 359/642, 359/722
• US Class Current: 501/55
• CPC Class Codes: C03C 3/078 containing an oxide of a divalent metal, e.g. an oxide of zinc
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/089 containing boron
• CPC Class Codes: C03C 3/091 containing aluminium

Abstract

The invention relates to lenses such as aspherical lenses and to a process for their manufacture. According to the invention, the lens is composed of a glass matrix including the constituents below in the following weight proportions:

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SiO₂ 65-85% Al₂ O₃ 0-10% B₂ O₃ 0-20% Li₂ O + Na₂ O + K₂ O 3-20% CaO + MgO + BaO 1-15% FeO + Fe₂ O₃ 0-0.1%, ______________________________________

wherein the K₂ O content is equal to or less than 1% and the BaO content is equal to or less than 1%.

Claims

1. An ellipsoidal headlamp lens, comprising a glass matrix consisting essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 65-85% Al.sub.2 O.sub.3 0-10% B.sub.2 O.sub.3 0-20% Li.sub.2 O + Na.sub.2 O + K.sub.2 O 3-20% CaO + MgO + BaO 0-15% FeO + Fe.sub.2 O.sub.3 0-0.1%, ______________________________________

wherein the K₂ O content is equal to or lower than 1% and the BaO content is equal to or lower than 1%,

said headlamp lens exhibiting a light transmission corresponding to the visible spectrum higher than 80%.

2. The ellipsoidal headlamp lens according to claim 1, wherein the CaO content is at least higher than 7%.

3. The ellipsoidal headlamp lens according to claim 1 wherein the glass matrix is a silica-soda-lime glass and consists essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 65-75% Al.sub.2 O.sub.3 0-10% Li.sub.2 O + Na.sub.2 O + K.sub.2 O 8-18% CaO + MgO + BaO 5-15% FeO + Fe.sub.2 O.sub.3 0-0.1%, ______________________________________

wherein the K₂ O content is equal to or lower than 1% and the BaO content is equal to or lower than 1%.

4. The ellipsoidal headlamp lens according to claim 1 wherein the glass matrix is a silica-soda-lime glass and consists essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 72-74% Al.sub.2 O.sub.3 1-3% Li.sub.2 O + Na.sub.2 O + K.sub.2 O 13-16% CaO + MgO + BaO 8-11% FeO + Fe.sub.2 O.sub.3 0-0.1%, ______________________________________

wherein the K₂ O content is equal to or lower than 1% and the BaO content is equal to or lower than 1%.

5. The ellipsoidal headlamp lens according to claim 1 wherein the glass matrix consists essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 73.50% Al.sub.2 O.sub.3 1.60% Na.sub.2 O 14.50% CaO 10.00%. ______________________________________

6. The ellipsoidal headlamp lens according to claim 1 wherein the glass matrix consists essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 71.40% Al.sub.2 O.sub.3 0.6% Na.sub.2 O 13.7% CaO 9.6% MgO 4.0%. ______________________________________

7. The ellipsoidal headlamp lens according to claim 1 wherein the glass matrix is a borosilicate glass and consists essentially of the constituents below in the following weight proportions:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 65-85% B.sub.2 O.sub.3 10-20% Li.sub.2 O + Na.sub.2 O + K.sub.2 O 3-20% Al.sub.2 O.sub.3 0-5%, ______________________________________

wherein the K₂ O content is equal to or lower than 1%.

8. The ellipsoidal headlamp lens according to one of the preceding claims, wherein it is aspherical.

9. Process for the manufacture of an ellipsoidal headlamp lens according to claim 1, wherein at least one glass component is heated to a temperature corresponding to a decimal logarithmic viscosity of between 4.5 and 5.5 and pressed.

10. Process according to claim 9, wherein the glass component is the end of a rod.

11. Process according to claim 9, wherein the glass component is a preform obtained by pressing a glass gob metered with a plunger having an orifice ring forming the end of a feeder.

12. Process according to claim 11, wherein the preform has a weight which is at least 15%, greater than that of the lens.

13. Process according to claim 11, wherein the preform is placed on a support during heating and pressing.