Heated Laminated Glass Layout to Suppress Windshield Flicker
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Solution Overview
Problem
Laminated glass windshields experience flicker issues when heated due to distortion of the resin layer around heating lines, causing a change in the refractive index and visible distortion when viewing outside objects.
Innovation Solution
The laminated glass design includes an intermediate layer with heating lines that generate 2.0 W/m or less heat per unit length, with specific voltage and resistance settings to prevent temperature exceedance and minimize flicker, featuring a heat-generating layer, adhesion layers, and bus bars to maintain the temperature below 60°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heating lines are used to defog the windshield, then defogging performance is improved, but flicker occurs when viewing outside objects
Solution Approach 1:
The patent changes the electrical parameters of the heating lines by setting specific resistance values (30Ω or more, preferably 90Ω or more) and controlling the amount of heat generated per unit length (2.0 W/m or less). This parameter optimization allows the heating lines to provide sufficient defogging performance while minimizing heat-induced distortion of the resin layer that causes flicker.
Solution Approach 2:
The patent applies partial heating action by distributing multiple heating lines across the windshield surface rather than using a single high-power heating element. This distributes the thermal load, preventing localized excessive heat generation that would cause significant resin layer distortion and flicker, while still achieving overall defogging coverage.
2Reliability
If heating lines generate sufficient heat for defogging, then defogging effectiveness is improved, but temperature exceeds 60°C causing resin layer distortion
Solution Approach 1:
The patent optimizes the heat generation parameters by specifying that each heating line generates 2.0 W/m or less when a predetermined voltage is applied. This controlled heat generation ensures the temperature of the intermediate layer remains at or below 60°C, preventing resin layer distortion while maintaining adequate defogging effectiveness through the cumulative effect of multiple heating lines.
Solution Approach 2:
The patent divides the heating function into multiple separate heating lines distributed across the windshield, each generating limited heat (2.0 W/m or less). This segmentation prevents any single location from exceeding the 60°C temperature threshold that causes resin distortion, while the collective heating effect of all lines maintains overall defogging performance.
3Use of energy by moving object
If voltage is increased to improve heating efficiency, then energy efficiency is improved, but heat generation increases causing flicker
Solution Approach 1:
The patent optimizes the electrical parameters by specifying resistance values of 30Ω or more (preferably 90Ω or more) and controlling heat generation to 2.0 W/m or less. This parameter configuration achieves energy-efficient heating by utilizing the vehicle's existing electrical system voltage while limiting excessive heat generation that would cause flicker, thereby balancing heating efficiency with optical clarity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses flicker when viewing outside objects through the windshield, ensuring clear visibility while maintaining sufficient heat for defogging or ice melting.
Implementation Method 1
when a current is applied to the heating lines to heat the laminated glass
Implementation Method 2
a resin layer around the heating lines is distorted by heat from the heating lines, and the refractive index of an intermediate layer changes due to this distortion
Data Source
AI summary
Laminated glass includes: an outer glass plate having a first side and a second side; an inner glass plate that is arranged opposing the outer glass plate and has substantially the same shape as a shape of the outer glass plate; and an intermediate layer arranged between the outer and the inner glass, wherein the intermediate layer has a heat-generating layer including: a first bus bar that extends along an end portion closer to the first side; a second bus bar that extends along an end portion closer to the second side; and a plurality of heating lines arranged so as to connect the first bus bar and the second bus bar to each other, and when a predetermined voltage is applied between the first and second bus bars, an amount of heat generated per unit length of each of the heating lines is 2.0 W/m or less.