Touch Sensor Substrate with Visible Light Absorption for Display Contrast
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Solution Overview
Problem
Conventional touch sensors integrated with image display devices experience a decrease in contrast and an increase in brightness of black display when black and white displays are shown, due to light transmission and scattering within the substrate.
Innovation Solution
A touch sensor with a substrate containing a visible light absorber, having an internal absorbance A1 of 0.03 or less and a parameter X of 30 m−1 or more, is used to reduce light transmission and scattering, maintaining contrast and suppressing brightness increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional touch sensor is integrated with an image display device, then the device can sense touch operations, but the contrast between black and white displays decreases and black display brightness increases
Solution Approach 1:
A light shielding layer is introduced as an intermediary component between the touch sensor and the image display element. This layer selectively blocks light in specific wavelength ranges (particularly blue light around 450-480nm) to prevent light from the white display portion from scattering into the black display portion, thereby maintaining high contrast while preserving the touch sensing function.
Solution Approach 2:
The patent modifies the optical parameters of the light shielding layer by controlling its thickness (5-20μm) and material composition to achieve specific light absorption characteristics. By adjusting these parameters, the layer absorbs harmful blue light while allowing other wavelengths to pass through, thus improving display contrast without significantly affecting overall brightness or touch sensing performance.
2Illumination intensity
If a light shielding layer is added to improve contrast, then display contrast improves, but device structure becomes more complex
Solution Approach 1:
The light shielding layer is integrated with the touch sensor substrate or positioned in close proximity within the existing lamination structure. By merging the light shielding function with the existing touch sensor assembly rather than adding a completely separate component, the patent improves contrast while minimizing increases in structural complexity.
3Illumination intensity
If the substrate thickness is reduced to improve contrast, then light scattering decreases, but mechanical strength decreases
Solution Approach 1:
The patent employs composite material structures where the substrate is combined with the light shielding layer having specific optical properties. This composite approach allows the system to achieve reduced light scattering equivalent to thinner substrates while maintaining the mechanical strength of the original substrate thickness through the supporting structure of the composite layers.
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
The touch sensor enhances contrast between black and white displays while preserving white display brightness, achieving display characteristics comparable to devices without a touch sensor.
Implementation Method 1
the substrate includes a visible light absorber, and the substrate has an internal absorbance A1 of 0.03 or less and a parameter X of 30 m−1 or more
Data Source
AI summary
A touch sensor that is excellent in contrast between black display and white display and is excellent in performance of suppressing a decrease in brightness of white display when the touch sensor is applied to an image display device and black and white display is made, as well as an image display device including the touch sensor. The touch sensor includes a substrate and a sensing electrode disposed on at least one surface side of the substrate. The substrate includes a visible light absorber, and the substrate has an internal absorbance A1 of 0.03 or less and a parameter X of 30 m−1 or more, the internal absorbance A1 and the parameter X being calculated with Test X.