LCD Pixel Unit With Dual Switches For Color Shift And Spiking
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Solution Overview
Problem
Existing liquid crystal display panels face challenges in achieving low color shift under wide viewing angles and image spiking issues due to the inherent properties of liquid crystal materials, while methods to address these problems often result in reduced aperture ratio and increased backlight costs.
Innovation Solution
The design incorporates a pixel unit with a data line, first and second scanning lines, switches, a storage capacitor, and a liquid crystal capacitor, where the second switch is configured to gradually reduce and instantaneously change the electric potential of the pixel electrode, allowing for different voltages during a frame and enabling black frame insertion without reducing aperture ratio or penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ITO region is divided into several domains with multiple TFTs to reduce color shift, then the color shift is reduced, but the aperture ratio decreases greatly
Solution Approach 1:
The pixel electrode is divided into multiple domains (first domain and second domain) with different voltage control mechanisms. Each domain can be independently controlled to achieve different brightness levels, reducing color shift while maintaining overall aperture ratio through shared transistor control structures.
Solution Approach 2:
The first TFT is designed to control both the first and second domains through its gate electrode connected to the first scanning line. This multi-functional design allows a single TFT to serve multiple pixel domains, reducing the total number of TFTs required and thereby increasing the aperture ratio while still achieving color shift compensation.
2Adaptability or versatility
If multiple TFTs are added to each pixel unit to achieve different brightness levels, then the brightness control is improved, but the device complexity increases
Solution Approach 1:
The first TFT serves multiple functions by controlling both the first domain (through direct connection to pixel electrode) and the second domain (through connection to second scanning line). This reduces the total TFT count per pixel while maintaining the capability to display different brightness levels across domains.
Solution Approach 2:
The second scanning line applies periodic scanning signals to the second domain at different timing within the frame period. This allows the same first TFT to control different domains at different times, achieving temporal multiplexing that reduces hardware complexity while maintaining brightness control versatility.
3Object-affected harmful factors
If the liquid crystal material response time is increased to track moving objects, then the image spiking is reduced, but the response rate decreases
Solution Approach 1:
The storage capacitor is pre-charged during the first time period before the black frame insertion period. This preliminary charging ensures that when the black frame is inserted, the liquid crystal molecules are already in a state ready for rapid transition, reducing the effective response time needed during the actual black frame period and thereby reducing image spiking without sacrificing overall response rate.
4Object-affected harmful factors
If a black frame is inserted between frames to eliminate image spiking, then the image quality is improved, but the display time is reduced
Solution Approach 1:
Instead of inserting a complete black frame that blocks all light, the patent applies a partial black frame approach where only specific domains (second domain) receive the black frame signal while other domains (first domain) continue displaying image content. This partial action reduces image spiking in the affected areas while maintaining overall display time and brightness.
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 approach achieves a low color shift display effect under wide viewing angles and eliminates image spiking by regulating the electric potential of the pixel electrode, allowing for different brightness levels and black frame insertion without increasing the cost of the backlight source.
Implementation Method 1
a liquid crystal capacitor Clc, one end of which is connected to the pixel electrode; a storage capacitor Cst, connected between the pixel electrode and the common electrode
Data Source
AI summary
A LCD panel and a driving method thereof are disclosed. The LCD panel comprises a plurality of pixel units, each pixel unit comprising: a data line, a first scanning line, a second scanning line, a first switch, a second switch, and a pixel electrode. When the first switch is turned on, said pixel electrode receives data signal of said data line and has an electric potential. During the process of said second switch being critically turned on for a certain time period, the electric potential of said pixel electrode decreases gradually through said second switch. At the moment when said second switch is completely turned on, the electric potential of said pixel electrode is changed instantaneously to a reference electric potential of said common electrode through said second switch. According to the present disclosure, one pixel can present different voltages during different time of one frame, and thus the low color shift display effect can be realized. Moreover, the electric potential of the pixel electrode can be changed to the reference electric potential of the common electrode at the set moment, so that the black frame insertion can be realized.