The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 1993
Filed:
Jun. 22, 1992
Bunryo Sato, Hachioji, JP;
Takeshi Nomura, Tokyo, JP;
Kiyoshi Yamamoto, Yokohama, JP;
Masaki Ohmori, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A method for press-forming a glass preform includes the steps of applying positioning pressure to an upper mold as the temperature of the upper mold and a lower mold increase to set values, maintaining a first temperature difference between the upper and lower molds of at least 10.degree. C. and increasing the temperature of the glass preform to a value above its glass transition temperature. Additional steps include cooling the upper and lower molds at a rate of 30.degree. to 100.degree. C. per minute while maintaining a temperature difference between the upper and lower molds at at least the first temperature difference, applying pressure to the lower mold, and opening the upper and lower molds to release the formed optical element after the temperatures of the upper and lower molds decrease to below a set value and a temperature difference between the upper and lower molds becomes greater than the first temperature difference.