LCD Logo Positioning Prevents Adhesive Peeling
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Solution Overview
Problem
The challenge in liquid crystal display devices is to maintain mechanical strength and reliability while reducing thickness, as thin glass substrates are prone to breaking under mechanical pressure, and the addition of a touch panel and front window with an adhesive layer or anti-reflection coating can lead to reduced light transmittance and stress peeling issues due to overlapping components.
Innovation Solution
A liquid crystal display device configuration where the touch panel and front window are bonded with an adhesive sheet, and a logo is formed on the front window with specific layer thicknesses and positioning to avoid overlapping with the touch-panel flexible wiring substrate, ensuring a plane distance greater than zero between the logo and the touch panel, thus preventing peeling stress and allowing for a thinner adhesive sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the liquid crystal display panel is reduced by polishing, then the overall size is reduced, but the mechanical strength is compromised and the panel may break under mechanical pressure
Solution Approach 1:
A front window made of resin or glass is attached to the screen side of the liquid crystal display panel before use, serving as a protective cushion that absorbs mechanical pressure and prevents the thin panel from breaking
Solution Approach 2:
The display device combines multiple materials (liquid crystal panel, touch panel, front window) with different properties to create a composite structure that achieves both thinness and mechanical strength
2Reliability
If adhesive layers or anti-reflection coatings are added between the liquid crystal display panel and touch panel, or between touch panel and front window, then the components are bonded together, but light transmittance is reduced due to reflection from interfaces
Solution Approach 1:
An adhesive layer serves as an intermediary between components, but anti-reflection coatings are applied to this layer to reduce light reflection while maintaining the bonding function
Solution Approach 2:
The optical parameters of the adhesive layer are modified by applying anti-reflection coatings, changing the refractive index gradient to reduce reflection and improve light transmittance
3Loss of information
If a logo is formed by printing on the back side of the touch panel, then the logo is displayed, but the thickness of the recoated portion increases to about 20 μm
Solution Approach 1:
The logo formation process is separated from the main touch panel structure, with the logo being formed on the front window instead, extracting the thick recoated portion from the critical bonding area
Solution Approach 2:
The logo is repositioned from the back side of the touch panel to the front window surface, changing its spatial location to avoid increasing thickness in the bonding region
4Adaptability or versatility
If the touch panel is mounted on the color filter substrate, then finger input function is enabled, but the overall thickness increases and mechanical strength decreases
Solution Approach 1:
The touch panel is integrated with the liquid crystal display panel through adhesive bonding, merging two functional components into a unified structure that maintains strength while enabling touch input
Data Source
AI summary
A mobile phone is provided which includes a liquid crystal display device in which a front window and a touch panel are bonded together with an adhesive sheet, wherein a logo having plural layers is formed on a back side of the front window. A touch-panel flexible wiring substrate is mounted to the touch panel. A plane distance between an end portion of the plural layers of the logo and an end portion of the touch panel is set to greater than zero. With this configuration, it is possible to prevent a peeling stress on the adhesive sheet, even if a thickness of the adhesive sheet is smaller than the sum of a thickness of the touch-panel flexible wiring substrate and a thickness of the logo.