IPS Liquid Crystal Display Light Transmittance Optimization
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Solution Overview
Problem
In horizontal electric field type liquid crystal display devices, the areas occupied by pixel and common electrodes do not contribute to aperture ratio and brightness due to the formation of vertical electric fields over these areas, reducing light transmittance and view angle.
Innovation Solution
The pixel and common electrodes are disposed closer, with a distance of 0.5 to 1.5 times their width, to ensure all liquid crystal molecules are driven by a horizontal electric field, enhancing light transmittance and aperture ratio, and a second passivation layer is optionally used to prevent damage from foreign materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pixel and common electrodes are formed on the same substrate in parallel to create horizontal electric field, then view angle and response speed are improved, but light transmittance is reduced due to vertical electric field formation over electrode areas
Solution Approach 1:
The patent introduces a third dimension (vertical stacking) by forming the common electrode on the upper substrate instead of the lower substrate. This dimensional change allows the electric field to be generated horizontally between the pixel electrode and common electrode without requiring lateral spacing, thereby eliminating the non-display area and maximizing light transmittance while maintaining the wide view angle characteristic of IPS mode.
2Illumination intensity
If pixel and common electrodes are disposed closer (0.5 to 1.5 times their width), then all liquid crystal molecules are driven by horizontal electric field improving light transmittance, but manufacturing precision requirements increase
Solution Approach 1:
The patent creates a uniform electric field distribution by optimizing the distance between pixel and common electrodes to be 0.5 to 1.5 times the electrode width. This equipotential design ensures that the electric field strength is uniform across the entire pixel area, including regions directly over the electrodes, enabling all liquid crystal molecules to be effectively driven without requiring excessive manufacturing precision.
3Illumination intensity
If pixel electrode area is increased to improve aperture ratio, then brightness is improved, but view angle may be compromised
Solution Approach 1:
By moving the common electrode to the upper substrate and forming it to extend across the entire pixel area, the patent achieves full aperture utilization without compromising view angle. The horizontal electric field configuration in IPS mode inherently provides wide view angle, and the vertical stacking allows the pixel electrode area to be maximized within the pixel definition area, simultaneously improving brightness and maintaining view angle performance.
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 ensures all liquid crystal molecules, including those over the electrodes, are driven by the horizontal electric field, improving light transmittance and aperture ratio while minimizing manufacturing complexity and cost.
Implementation Method 1
the liquid crystal molecules of the liquid crystal layer disposed between the thin film transistor array substrate and the color filter substrate are rotated by the dielectric anisotropy
Implementation Method 2
the alignment layer ALG defining the initial alignment direction of the liquid crystal molecules LCM of the liquid crystal layer
Data Source
AI summary
The present disclosure relates to a horizontal electric field type liquid crystal display device having the horizontal electric fields over the pixel electrodes and the common electrodes which are disposed on the same level plane, and a method for manufacturing the same. The horizontal electric field type liquid crystal display device comprising: a substrate; a gate line and a data line crossing each other with a gate insulating layer therebetween, and defining a pixel area on the substrate; a thin film transistor formed where the gate line and the data line is crossing; a pixel electrode contacting the thin film transistor on the gate insulating layer; a common electrode disposed in parallel with the pixel electrode having a predetermined distance; and a passivation layer covering whole surface of the substrate including the pixel electrode and the common electrode. According to the present disclosure, as all liquid crystal molecules including molecules disposed right over the pixel electrodes and the common electrodes are driven by the horizontal electric field, the light transmittance and the aperture ratio are enhanced.