| 摘要 |
<p>478,759. Compound glass. TENNANT, W. J. (American Optical Co.) Nov. 3, 1936, No. 29914. [Class 140] A composite safety glass or like article, e.g. an ophthalmic lens or motor-car windscreen, comprises a layer of non - brittle bonding material faced on both sides with adherent layers of vitreous material, one of the layers being relatively thick, and hardened to resist impact, and the other layer being unhardened, substantially strain free, and sufficiently thin to eliminate substantially all danger of surface splinters becoming detached. Both layers have a finished surface on the exposed face. In examples : (1) a motor-car windscreen has a hardened layer of plate glass three-sixteenths of an inch thick, and an unhardened layer of plate glass one-sixteenth of an inch thick ; (2) an ophthalmic lens has a hardened layer of optical crown glass of two-millimeters minimum thickness and a strain-free layer of optical crown glass of one-millimeter maximum thickness. As shown, the meniscus-shaped ophthalmic lens has the hardened thick layer 1, which in use faces forwards away from the eye, formed with a finished convex surface 6 on the exposed face. The non-brittle bonding layer may be formed of cellulose nitrate or acetate composition, polymerized vinyl compound, polymerized styrene, acrylic acid or acrylic acid esters or the like, plasticized with chlorinated diphenyl, diethyl phthalate or the like. Specification 396,313 is referred to.</p> |
