Liquid Crystal Display Touch Panel Photo-Sensing Elements
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Solution Overview
Problem
Conventional LCD touch panels either decrease light transmittance and increase thickness due to added resistors or capacitors, or enlarge the product size with optical touch panels, failing to meet the demand for compact and lightweight designs.
Innovation Solution
Integrating photo-sensing elements within the liquid crystal panel to detect light intensity variations and determine touch positions, using a light source, reflecting elements, and photo-sensing elements on substrates to calculate the applied force's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resistors or capacitors are directly disposed on the LCD panel to enable touch control, then touch functionality is achieved, but light transmittance decreases and panel thickness increases
Solution Approach 1:
The patent replaces the conventional resistor/capacitor-based electrical detection system with an optical detection system using light sources and photo-sensing elements. This substitution eliminates the need for additional electrical components on the panel, thereby maintaining light transmittance while achieving touch control functionality through optical field changes caused by touch pressure.
Solution Approach 2:
The patent introduces light sources and photo-sensing elements as intermediary components that mediate between the touch input and the control system. These intermediaries detect touch positions through optical field variations rather than direct electrical contact, avoiding the need for resistors or capacitors that would block light.
2Adaptability or versatility
If resistors or capacitors are directly disposed on the LCD panel to enable touch control, then touch functionality is achieved, but panel thickness increases
Solution Approach 1:
The patent replaces the thick electrical components (resistors/capacitors) with thin optical components (light sources and photo-sensing elements) that can be integrated into the panel structure without significantly increasing thickness. The optical detection method requires minimal additional space compared to electrical components.
Solution Approach 2:
The patent employs thin-film integration of photo-sensing elements and light sources within the panel structure, allowing touch detection functionality to be incorporated without adding substantial thickness. The optical components are arranged in thin layers that maintain the panel's overall thin profile.
3Illumination intensity
If optical touch panels with light sources and detecting elements are used, then light transmittance is maintained, but product size significantly increases
Solution Approach 1:
The patent merges the light sources and photo-sensing elements with the existing LCD panel structure, integrating them into the same space rather than placing them as separate external components. This consolidation allows optical touch detection to be achieved without significantly increasing the overall product footprint.
Solution Approach 2:
The patent designs the light sources and photo-sensing elements to serve multiple functions: they are integrated into the display structure for touch detection while also being arranged to minimize impact on the overall product dimensions. The same optical components perform both display illumination and touch detection functions.
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 solution reduces the weight and size of LCDs while maintaining light transmittance, aligning with the compact trend in the market by accurately determining touch positions and force magnitude through light intensity detection.
Implementation Method 1
a photo-sensing element, formed on the second substrate, for outputting a sensing parameter based on light reflected from the reflecting member. A position of the force applied on the first substrate is determined by detecting a variation of the sensing parameter outputted by the photo-sensing element
Data Source
AI summary
A liquid crystal display includes a light source for emitting light, a first substrate, a second substrate parallel to and facing the first substrate, and a plurality of pixel units formed between the first substrate and the second substrate. At least one pixel unit comprises a reflecting element disposed on the first substrate for reflecting light from the light source, and a photo-sensing element, formed on the second substrate, for outputting a sensing parameter based on light reflected from the reflecting member. Each reflecting element is extended out of the first substrate and faces to one of the plurality of photo-sensing elements. A position of the force applied on the first substrate is determined by detecting a variation of the sensing parameter outputted by the photo-sensing element.