Bus bar arrangement for uniformly heating a trapezoidally-shaped electrically heated windshield

• US 4,543,466 A
• Filed: 07/02/1984
• Issued: 09/24/1985
• Est. Priority Date: 07/02/1984
• Status: Expired due to Fees

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Ramus, Kevin J.
• Primary Examiner(s): Bartis, A.
• Application Number:
  US06/627,266
• Time in Patent Office: 449 Days
• Field of Search: 219/203, 219/522, 219/547, 219/543, 219/345, 219/213, 219/541, 338/308, 338/309, 52/170, 52/171
• US Class Current: 219/203
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: H05B 2203/016 Heaters using particular connecting means
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

An electrically heated windshield of generally trapezoidal shape has been bus bars of uniform conductivity throughout their length extending in line contact with the upper and lower edges of a continuous uniformly thick trapezoidal-shaped electrically conductive coating provided on the windshield surface for deicing and defrosting the windshield. The line of contact of the upper bus bar with the conductive coating has a length generally equal to the entire effective length of the upper edge of the conductive coating. The lower bus bar is symetrically located along the lower edge of the conductive coating and has a line of contact length equal to the sum of the length of the upper bus bar plus generally about one-half the difference between the entire effective length of the lower edge of the conductive coating minus the length of the line of contact of the upper bus bar.

Claims

1. In an electrically heated windshield construction in which said windshield (a) is of generally trapezoidal shape, (b) has both an upper generally horizonally extending bus bar of uniform conductivity throughout its length and a lower generally horizonally extending bus bar of uniform conductivity throughout its length, and (c) a continuous and uniformly thick trapezoidal-shaped electrically conductive coating on said windshield which electrically interconnects said upper bus bar and said lower bus bar;

an improved bus bar configuration in which;

said bus bars are formed in a manner such that (1) the line of contact of said upper generally horizonally extending bus bar with said electrically conductive coating has a length which extends generally along an entire effective length of an upper edge of said electrically conductive coating on said windshield, and (2) the line of contact of said lower generally horizontally extending bus bar being symetrically located on the lower edge of said electrically conductive coating and having a length equal to the sum of said length of said line of contact of said upper bus bar plus generally about one-half of the difference between the entire effective length of the lower edge of said electrically conductive coating on said windshield minus said length of said line of contact of said upper bus bar.

2. The electrically heated windshield construction of claim 1, wherein said line of contact of said lower generally horizontally extending bus bar with the lower edge of said electrically conductive coating has a length plus or minus fifteen percent (15%) of a length equal to the sum of said length of said line of contact of said upper bus bar plus generally about one-half of the difference between the entire effective length of the lower edge of said electrically conductive coating on said windshield minus said length of said line of contact of said upper bus bar.