Kenneth L Collier

US Patent:

39743594, Aug 10, 1976

Filed:

Jun 9, 1975

Appl. No.:

5/585417

Inventors:

Dee R. Orcutt - Huntsville AL
Kenneth C. Collier - Huntsville AL

Assignee:

PPG Industries, Inc. - Pittsburgh PA

International Classification:

H05B 306

US Classification:

219522

Abstract:

A laminated glass-plastic glazing unit suitable for aircraft is disclosed. The unit comprises a pair of sheets of rigid transparent material such as glass and an interlayer of thermoplastic material that is susceptible to crack at low temperatures and that has a higher coefficient of thermal expansion than the sheets of rigid transparent material. Electrical resistance material preferably in the form of thin metal wire, is embedded within the interlayer and disposed locally in areas along a pair of opposite marginal edges of the interlayer and electrically energized to heat the interlayer portion adjacent thereto sufficiently to overcome the tendency of the interlayer to pull chips from the marginal portion of one or both of the rigid sheets when the unit is subjected to extremely low temperature conditions in a high-flying aircraft. The electroconductive material is embedded within the interlayer in spaced relation to a transparent electroconductive coating on one of the glass sheets for heating the glazing unit to dissipate mist or frost and is located relative to the thickness of the interlayer in a plane that is closer to the rigid sheet more likely to become damaged when the unit is exposed to the aforesaid low temperature conditions. The interlayer may also include a metal reinforcement frame in heat exchanging relation to the electroconductive material that extends to the edge of the interlayer to conduct heat received from the electroconductive material to the edge of the interlayer, thereby retarding the cooling of the edge of the interlayer to a temperature at which it cracks.