Capacitive Touch Panel Adhesive Tan Delta Control
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Solution Overview
Problem
Capacitive touch panels experience malfunctions due to increased energy loss and electrostatic capacitance changes when exposed to varying temperatures, particularly as screen size increases, leading to instability in detection accuracy.
Innovation Solution
The capacitive touch panel design controls the dielectric tangent (tan σ) of both the lower and upper adhesive layers to ensure they remain below a predetermined value, with the lower adhesive layer's tan σ being equal to or less than the upper adhesive layer's, thereby minimizing energy loss and maintaining stable electrostatic capacitance across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If screen size of the capacitive touch panel is increased, then the display area is enlarged, but malfunction occurs easily under various use environments
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dielectric properties (tan σ) of the adhesive layers. By specifying that tan σ of the lower adhesive layer and upper adhesive layer must satisfy predetermined relationships (maximum values of 0.08 or less, with the lower layer's tan σ being equal to or less than the upper layer's at each temperature), the invention optimizes the electrical characteristics to prevent malfunction while maintaining large screen size
2Ease of manufacture
If adhesive layer's dielectric tangent (tan σ) is not controlled, then manufacturing is simpler, but energy loss increases and electrostatic capacitance becomes unstable
Solution Approach 1:
The patent specifies precise parameter ranges for tan σ of the adhesive layers (maximum value of 0.08 or less) to minimize energy loss and stabilize electrostatic capacitance, while still allowing use of conventional adhesive materials within these ranges
3Ease of manufacture
If adhesive layer's dielectric tangent (tan σ) is not controlled, then manufacturing is simpler, but position detection accuracy decreases
Solution Approach 1:
The patent controls the dielectric properties (tan σ) of the adhesive layers to maintain stable electrostatic capacitance characteristics, which is essential for accurate position detection. The specified parameter relationships ensure that the adhesive layers do not introduce instability that would degrade detection precision
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 significantly reduces malfunctions in capacitive touch panels across a wide temperature range, ensuring accurate position detection and preventing malfunctions even in larger screen sizes.
Implementation Method 1
a maximum value of tan σ of the upper adhesive layer and a maximum value of tan σ of the lower adhesive layer, which are obtained from a temperature dependency evaluation test (Test 1) are 0.08 or less, and also tan σ of the lower adhesive layer at respective temperatures of every 20° C. from −40° C. to 80° C. is tan σ or less of the upper adhesive layer
Data Source
AI summary
The invention provides a capacitive touch panel that hardly cause malfunction in a wide range of temperature environment from a low temperature to a high temperature. The capacitive touch panel according to the invention is a capacitive touch panel including a display device, a lower adhesive layer, a capacitive touch panel sensor, an upper adhesive layer, and a protective substrate in this order, in which a maximum value of tan σ of the upper adhesive layer and a maximum value of tan σ of the lower adhesive layer obtained from a temperature dependency evaluation test is 0.08 or less, and tan σ of the lower adhesive layer at each temperature of every 20° C. from −40° C. to 80° C. is equal to or less than tan σ of the upper adhesive layer.