Heatable article having a configured heating member

• US 20040065651A1
• Filed: 10/03/2002
• Published: 04/08/2004
• Est. Priority Date: 10/03/2002
• Status: Active Grant

• Current Assignee: Vitro Flat Glass LLC (Compagnie De Saint-Gobain)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Voeltzel, Charles S.
• Granted Patent: US 7,132,625 B2
• Time in Patent Office: Days
• US Class Current: 219/203
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10192 patterned in the form of columns or grids
• CPC Class Codes: B32B 17/10293 Edge features, e.g. inserts or holes
• CPC Class Codes: H05B 2203/008 with layout including a portion free of resistive material, e.g. communication window
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 3/86 the heating conductors being embedded in the transparent or reflecting material H05B3/845 takes precedence

Abstract

A heatable article, e.g. a heatable windshield, having a generally trapezoidal shape has a conductive member, e.g. a conductive coating, between and in contact with a pair of spaced bus bars having different lengths. Selected portions of the coating between the bus bars are segmented to reduce the difference in watt density between the coatings at the bus bars when current moves through the coating. In one non-limiting embodiment, the width of the segments at the longer bus bar is less than the width of the segments at the longer bus bar. With this configuration, the watt density at the bottom of the windshield is increased to more efficiently remove ice and snow. In another non-limiting embodiment, the coating has a communication window to pass frequencies of the electromagnetic spectrum, e.g. RF frequencies, to obtain information from within the vehicle. The coating surrounding the conductive window has break lines to segment the coating to eliminate hot spot around the periphery of the communication window.

Claims

1. A heatable article comprising:

a first bus bar;

a second bus bar spaced from the first bus bar;

an electrically conductive member between and in electric contact with each of the bus bars, wherein the conductive member adjacent the first bus bar has a plurality of discreet electrically isolated electrically conductive segments with at least one of the segments having varying width as the distance from the first bar toward the second bus bar increases

2. The heatable article according to claim 1 wherein the electrically conductive member is continuous from the second bus bar to a position between the bus bars defined as a transition position and the plurality of discreet electrically isolated electrically conductive segments extend from the transition position to the first bus bar wherein selected ones of the conductive segments have increasing width as the distance from the first bus bar toward the second bus bar increases.

3. The heatable article according to claim 1 wherein the plurality of discreet electrically isolated electrically conductive segments extend from the first bus bar to the second bus bar and the width of selected ones of the conductive segments increases as the distance from the first bus bar toward the second bus bar increases.

4. The heatable article according to claim 1 wherein the plurality of discreet electrically isolated electrically conductive segments extend from the first bus bar to the second bus bar and selected ones of the conductive segments have a decreasing width from the first bus to a position between the first and second bus bar defined as a transition position and an increasing width from the transition position to the second bus bar.

5. The heatable article according to claim 4 wherein the width of the selected ones of the conductive segments at the transition position is less than the width of the selected ones of the conductive segments at the first bus bar.

6. The heatable article according to claim 1 wherein the plurality of discreet electrically isolated electrically conductive segments extend from the first bus bar to the second bus bar and the width of selected ones of the conductive segments decreases as the distance from the first bus bar toward the second bus bar increases.

7. The heatable article according to claim 1 wherein the plurality of discreet electrically isolated electrically conductive segments are a first plurality of discreet electrically isolated electrically conductive segments and further including a second plurality of discreet electrically isolated electrically conductive segments, the first and second plurality of conductive segments extend from the first bus bar to the second bus bar and the width of the first plurality conductive segments increases as the distance from the first bus bar increases and the width of the second plurality of conductive segments is substantially constant from the first bus bar to the second bus bar.

8. The heatable article according to claim 1 wherein the conductive member has an area defined as a communication window, the resistance within the communication window is greater than the resistance outside and adjacent the communication window, the plurality of discreet electrically isolated electrically conductive segments extend from one bus bar to the other bus bar and surround the communication window.

9. The heatable article according to claim 8 wherein the communication window is adjacent the first bus bar and the plurality of discreet electrically isolated electrically conductive segments extend from the first bus bar toward the communication window, selected ones of the plurality of discreet electrically isolated electrically conductive segments extend in first direction around the communication window and selected ones of the plurality of discreet electrically isolated electrically conductive segments extend in a second direction opposite to the first direction around the communication window.

10. The heatable article according to claim 1 further including a substrate having a major surface wherein the electrically conductive member is a conductive coating applied to the major surface of the substrate.

11. The heatable article according to claim 10 wherein the conductive coating is a sputtered coating having at least one electrically conductive film between a pair of dielectric films.

12. The heatable article according to claim 10 wherein the substrate is a first piece of glass and further including:

a second piece of glass;

a plastic sheet between the first and second pieces of glass securing the first and second pieces of glass together with the bus bars and the conductive coating between the first piece of glass and the plastic sheet.

13. The article according to claim 12 wherein the article is a transparence for use on an enclosure of the type selected from the group consisting of a residential home, a commercial building, a space vehicle, an air vehicle, a land vehicle, an over the water vehicle, an under the water vehicle, a refrigerator having a door with a viewing area and combinations thereof.

14. The article according to claim 13 wherein the article is a transparence for an automobile selected from the group consisting of a windshields, side window, back window, moon roof and combinations thereof and the conductive coating is a sputtered coating having at least one electrically conductive film between a pair of dielectric films.

15. The article according to claim 14 wherein the article is an automotive windshield and the first bus bar is longer than the second bus bar.

16. The automotive transparency according to claim 15 wherein the coating is continuous from the second bus bar to a position between the bus bars defined as a transition position and the plurality of discreet electrically isolated coating segments extend from the transition position to the first bus bar wherein selected ones of the coating segments have increasing width as the distance from the first bus bar increases.

17. The automotive transparency according to claim 15 wherein the plurality of discreet electrically isolated coating segments extend from the first bus bar to the second bus bar and the width of selected ones of the conductive segments increases as the distance from the first bus bar increases.

18. The automotive transparency according to claim 15 wherein the plurality of discreet electrically isolated coating segments extend from the first bus bar to the second bus bar and selected ones of the coating segments have a decreasing width from the first bus to a position between the first and second bus bar defined as a transition position and an increasing width from the transition position to the second bus bar.

19. The automotive transparency according to claim 18 wherein the width of the selected ones of the coating segments at the transition position is less than the width of the selected ones of the coating segments at the first bus bar.

20. The automotive transparency according to claim 15 wherein the plurality of discreet electrically isolated electric coating segments extend from the first bus bar to the second bus bar and the width of selected ones of the coating segments decreases as the distance from the first bus bar increases.

21. The automotive transparency according to claim 15 wherein the plurality of discreet electrically isolated electric coating segments are a first plurality of discreet electrically isolated electric coating segments and further including a second plurality of discreet electrically isolated electric coating segments, the first and second plurality of coating segments extend from the first bus bar to the second bus bar and the width of the first plurality coating segments increases as the distance from the first bus bar increases and the width of the second plurality of coating segments is substantially constant from the first bus bar to the second bus bar.

22. The automotive transparency according to claim 15 wherein the plurality of discreet electrically isolated electric coating segments are a first plurality of discreet electrically isolated electric coating segments and further including a second plurality of discreet electrically isolated electric coating segments, the first and second plurality of coating segments extend from the first bus bar to the second bus bar and the width of the first plurality coating segments decreases as the distance from the first bus bar increases and the width of the second plurality of coating segments is substantially constant from the first bus bar to the second bus bar.

23. The automotive transparency according to claim 15 wherein the coating has an area defined as a communication window, the resistance within the communication window is greater than the resistance outside and adjacent the communication window, the plurality of discreet electrically isolated electric coating segments extend from one bus bar to the other bus bar and are on each side of the communication window.

24. The automotive transparency according to claim 23 wherein the communication window is adjacent the first bus bar and the plurality of discreet electrically isolated electrically conductive segments extend from the first bus bar toward the communication window, selected ones of the plurality of discreet electrically isolated electric coating segments extend in a first direction around the communication window and selected ones of the plurality of discreet electrically isolated electric coating segments extend in a second direction opposite to the first direction around the communication window.

25. The automotive transparency according to claim 15 further including:

a first lead contacting the first bus bar and extending out from between the first and second glass pieces to provide external electrical access to the first bus bar, and

a second lead contacting the second bus bar and extending out from between the first and second glass pieces to provide external electrical access to the second bus bar.

26. The automotive transparency according to claim 15 wherein the conductive member is defined by a perimeter with the perimeter of the conductive member spaced from the periphery of the first glass piece and area between the perimeter of the conductive member and the periphery of the first glass sheet is defined as a non-conductive strip and each end portion of each one of the bus bars extends into the non-conductive strip.

27. The automotive transparency according to claim 15 wherein at least one of the outer major surfaces of one of the glass pieces includes a hydrophobic coating.

28. The automotive transparency according to claim 15 wherein at least one of the outer major surfaces of one of the glass piece includes a photocatalytic coating.

29. The automotive transparency according to claim 15 wherein the plastic sheet is selected from the group consisting of polyvinyl butyral, polyvinyl chloride, polyethylene and combinations thereof.

30. The automotive transparency according to claim 15 wherein at least one of the glass sheets or the plastic sheet has a portion in cross section having a wedged shape.

31. A heatable article comprising:

a pair glass sheets;

at least one plastic sheet between the pair of glass sheets securing the glass sheets together;

a first and a second bus bar between the glass sheets and spaced from one another, wherein the first bus bar is longer than the second bus bar;

an electrically conductive member between the glass sheets, and between and in electric contact with the first and second bus bars;

the conductive member having at least two discreet segments in electrical contact with one of the bus bars wherein the watt density of the conductive member adjacent the first bus bar is at least 80% of the watt density of the conductive member adjacent the second bus bar.

32. The heatable article according to claim 31 wherein the watt density of the conductive member adjacent the first bus bar is at least 90% of the watt density of the conductive member adjacent the second bus bar.

33. The heatable article according to claim 32 wherein the watt density of the conductive member adjacent the first bus bar is at least 95% of the watt density of the conductive member adjacent the second bus bar.

34. The heatable article according to claim 31 wherein the article is an automotive transparency and the conductive member is a coating having a conductive film between a pair of dielectric films.

35. The automotive transparency according to claim 34 wherein the ends of the first and second bus bars are closer together than the portions of the bus bars between their ends.

36. The automotive transparency according to claim 34 wherein the coating is a plurality of discrete electrically isolated segments wherein at least on one of the segments has a width greater at the first bar than at the second bus bar.

37. The automotive transparency according to claim 34 wherein the coating is a plurality of discrete electrically isolated segments wherein the width of at least on one of the segments at the first and second bus bars is the same.

38. The automotive transparency according to claim 34 wherein the coating is a plurality of discrete electrically isolated segments wherein at least on one of the segments has a width smaller at the first bar than at the second bus bar.

39. The automotive transparency according to claim 36 wherein the segments between and in contact with the first and second bus bars are a first group of segments and further including an intervening segment between adjacent segments of the first group of segments, the intervening segments between the first and second bus bars, only in electrical contact with one of the bus bars and electrically isolated from the first group of segments.

40. The automotive transparency according to claim 34 wherein the bus bars and the coating is between facing major surface of the glass sheet and the plastic sheet.

41. The automotive transparency according to claim 34 wherein the at least one plastic sheet is a first plastic sheet and further including a second plastic sheet with the bus bars and coating between the first and second plastic sheets.