Automobile windshield and its method of fabrication

Claim 2

AN ARTICLE COMPRISING A GLASS SHEET HAVING A GLASS SHEET PORTION ADAPTED TO BE SHARPLY BENT EXTENDING FROM EDGE TO EDGE ACROSS A DIMENSION OF SAID GLASS SHEET, A LAYER OF ELECTROCONDUCTIVE MATERIAL ON A SURFACE OF SAID SHEET ARRANGED IN AN ELECTROCONDUCTIVE PATTERN COMPRISING AN ELONGATED ELECTROCONDUCTIVE PORTION HAVING A GIVEN ELECTROCONDUCTIVITY PER UNIT LENGTH AND BONDED TO SAID GLASS SHEET PORTION TO BE SHARPLY BENT AND APPROXIMATELY COEXTENSIVE IN LENGTH THEREWITH, AND AN EDGE PORTION OF ELECTROCONDUCTIVE MATERIAL BONDED TO SAID GLASS SHEET AND EXTENDING FROM EACH END PORTION OF SAID ELONGATED ELECTROCONDUCTIVE EDGE PORTION INCLUDING A GLASS SHEET, SAID ELECTROCONDUCTIVE EDGE PORTION INCLUDING A LESS CONDUCTIVE EDGE PORTION WHOSE ELECTROCONDUCTIVITY PER UNIT LENGTH IS APPROXIMATELY EQUAL TO THAT OF THE FIRST NAMED ELONGATED ELECTROCONDUCTIVE PORTION CONTACTING AN END PORTION OF SAID FIRST NAMED ELONGATED ELECTROCONDUCTIVE PORTION AND A MORE CONDUCTIVE ELECTROCONDUCTIVE EDGE PORTION, WHOSE ELECTROCONDUCTIVITY PER UNIT LENGTH IS GREATER THAN THAT OF SAID ELONGATED ELECTROCONDUCTIVE PORTION, REMOTE FROM SAID ELONGATED ELECTROCONDUCTIVE PORTION, SAID PATTERN BEING SO CONSTRUCTED AND ARRANGED THAT WHEN ELECTROCONDUCTIVE ENERGY IS APPLIED TO SAID ELECTROCONDUCTIVE PATTERN TO HEAT SAID ELECTROCONDUCTIVE MATERIAL, THE TEMPERATURE GRADIENT ALLONG THE EDGE PORTIONS OF THE GLASS IN THE VICINITY OF THE END PORTION OF SAID FIRST NAMED ELONGATED ELECTROCONDUCTIVE PORTION IS NOT SO STEEP AS TO CAUSE THE GLASS TO B BREAK FROM THERMAL STRESS.

Claim 3

An article as in claim 1, wherein one of said electroconductive edge portions extends away from said first named elongated electroconductive portion along one edge portion of said article and the other of said electroconductive edge portions extends away from said first named elongated electroconductive Portion along an edge portion of said article opposite said one edge portion of said article.

Claim 4

An article as in claim 1, wherein each said electroconductive edge portion is symmetrical with respect to one or the other end of said first named elongated electroconductive portion and comprises a relatively narrow electroconductive center edge portion contacting said first named elongated electroconductive portion and wider electroconductive end edge portions spaced from said elongated electroconductive portion.

Claim 5

An article as in claim 1, wherein said electroconductive pattern is composed of a metalo-ceramic composition.

Claim 6

An article as in claim 4, wherein said metalo-ceramic composition has a coefficient of thermal expansion that is between about 45 to 90 times 10 7 per degree Centigrade, whereby its said coefficient is compatible with that of said glass sheet.

Claim 7

An article as in claim 1, wherein said pattern is composed of a noble metal or a noble metal alloy.

Claim 8

An article as in claim 6, wherein the noble metal is silver.

Claim 9

An article as in claim 1, wherein said glass sheet is sharply bent along said dimension of said sheet to form a bent window.

Claim 10

A window as in claim 8, further comprising a second glass sheet conforming in shape and outline to said first named glass sheet and means adhering said glass sheets to one another in aligned relationship.

Claim 11

A window as in claim 9, wherein said adhering means is a polyvinyl acetal.

Claim 12

A window as in claim 9, wherein said adhering means is a polyurethane resin.

Claim 13

A window as in claim 9, wherein each of said glass sheets is provided with a pattern of electroconductive material comprising an elongated electroconductive portion bonded to its said sharply bent portion, and one of said electroconductive edge portions at each end of said elongated electroconductive portion bonded to said first glass sheet extends in a different direction from the direction in which the corresponding electroconductive edge portion extends from said elongated electroconductive portion bonded to said second glass sheet.

Claim 14

A window as in claim 8, further comprising a sheet of flexible plastic resin bonded to a surface of said glass sheet.

Claim 15

A window as in claim 13, wherein said resin is a polyvinyl acetal.

Claim 16

A window as in claim 13, wherein said resin is a polyurethane resin.

Claim 17

A window as in claim 8, wherein said elongated electroconductive portion is disposed along an elongated valley formed on the surface of said glass sheet forming said sharply bent glass sheet portion.

Claim 18

A window as in claim 8, wherein each said electroconductive edge portion is symmetrical with respect to one or the other end of said first named elongated electroconductive portion and comprises a relatively narrow electroconductive center edge portion contacting said first named elongated electroconductive portion and wider electroconductive end edge portions spaced from said elongated electroconductive portion.

Claim 19

A window as in claim 8, wherein said electroconductive pattern is composed of a metalo-ceramic composition.

Claim 20

A window as in claim 18, wherein said metalo-ceramic composition has a coefficient of thermal expansion that is between about 45 to 90 times 10 7 per degree Centigrade, whereby its said coefficient is compatible with that of said glass sheet.

Claim 21

A window as in claim 8, wherein said pattern is composed of a noble metal or a noble metal alloy.

Claim 22

A window as in claim 20, wherein the noble metal is silver.

Claim 23

A window as in claim 8, wherein said sharply bent glass sheet portion extends across the width of said glass sheet to form two main glass sheet portions symmetrically arranged with respect to said sharply bent glass sheet portion.

Claim 24

A window as in claim 22, further including a second glass sheet conforming in shape and outline to said first named glass sheet and means adhering said glass sheets to one another in aligned relationship.

Claim 25

A window as in claim 22, comprising a layer of plastic resin bonded to said glass sheet.

Claim 26

In a method of bending a glass sheet to a sharp bend comprising applying a layer of electroconductive material to a surface of said sheet arranged in an electroconductive pattern comprising an elongated electroconductive portion having a given electroconductivity per unit length along a line about which it is desired to bend said sheet, applying an electrical voltage across said line of a sufficient magnitude and for sufficient duration to heat said sheet in the vicinity of said line to a temperature at which said glass bends to form said sharp bend, the improvement comprising applying an additional edge portion of electrically conductive material to said surface along an edge portion of said glass sheet in electrical contact with said first named elongated electroconductive portion and extending along said glass sheet edge portion from each end of said first elongated electroconductive element, each said additional electroconductive edge portion having a first electroconductive portion having an electroconductivity per unit length approximately equal to that of said first named elongated electroconductive portion in electrical contact with one or the other end of said first named elongated electroconductive portion and a second electroconductive portion having a greater electroconductivity per unit length than that of said first named elongated electroconductive portion remote from said first named elongated electroconductive portion and making electrical contact at said second portion with an electrode connected to a source of said electrical voltage to apply said electrical voltage across said first named elongated electroconductive portion, whereby when said voltage is applied to said electroconductive pattern, the temperature gradient along the edge portions of the glass in the vicinity of the end portions of said first named elongated electroconductive portion is not so steep as to cause the glass to break from thermal stress.

Claim 27

In a method of bending a glass sheet to a sharp bend comprising applying a layer of electroconductive material to a surface of said sheet arranged in an electroconductive pattern comprising an elongated electroconductive portion having a given electroconductivity per unit length along a line about which it is desired to bend said sheet, applying an electrical voltage across said line of a sufficient magnitude and for sufficient duration to heat said sheet in the vicinity of said line to a temperature at which said glass bends to form said sharp bend, the improvement comprising applying an additional edge portion of electrically conductive material to said surface along an edge portion of said glass sheet in electrical contact with said first named elongated electroconductive portion and extending along said glass sheet edge portion from each end of said first elongated electroconductive element, each said additional electroconductive edge portion having a first electroconductive portion having an electroconductivity per unit length approximately equal to that of said first named elongated electroconductive portion in electrical contact with one or the other end of said first named elongated electroconductive portion and a second electroconductive portion having a greater electroconductivity per unit length than that of said first named elongated electroconductive portion remote from said first named elongated electroconductive portion and making electrical contact at said second portion with an electrode connected to a source of said electrical voltage to apply said electrical voltage across said first named elongated electroconductive portion, whereby when said voltage is applied to said electroconductive pattern, the temperature gradient along the edge portions of the glass in the vicinity of the end portions of said first named elongated electroconductive portion is not so steep as to cause the glass to break from thermal stress.

Claim 28

The improvement as in claim 25, wherein said electrode is clamped to said second electroconductive portion.

Claim 29

The improvement as in claim 25, wherein said first named elongated electroconductive portion and said additional electroconductive edge portions have substantially equal thickness and are applied in the same application step.

Claim 30

In the method as in claim 25, the improvement comprising applying a layer of electroconductive material arranged in said electroconductive pattern on a surface of a second glass sheet conforming to said first glass sheet, aligning said glass sheets so that said elongated electroconductive portions are aligned with one another, supporting said first and second glass sheets in shaping relation to a glass sheet bending mold with said elongated electroconductive portions aligned and parting material disposed between said glass sheets, shaping said glass sheets into conformity with said bending mold to form bent glass sheets, assembling said bent glass sheets with interlayer material therebetween and applying sufficient heat and pressure to said assembly so formed to laminate said glass sheets to said interlayer material.

Claim 31

In the method as in claim 25, the further step of laminating said bent glass sheet to interlayer material comprising polymeric material taken from the class consisting of polyurethanes and polyvinyl butyral.